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Frequently Asked Questions (FAQs) About Snakes

Updated on June 8, 2017

Snakes: Creatures Shrouded in Mystery

Snakes are often one of those creatures whose poor reputation precedes them. Although some do get a bad rap for legit reasons, snakes are commonly just misunderstood creatures that are feared, hated, and killed on sight. This FAQ aims to change that.
Snakes are often one of those creatures whose poor reputation precedes them. Although some do get a bad rap for legit reasons, snakes are commonly just misunderstood creatures that are feared, hated, and killed on sight. This FAQ aims to change that.

Introduction To These Snake FAQs

Have you ever had a question about snakes that you just couldn't find the answer for? Or maybe you've found an answer, but just didn't know if you could trust the information? Well, look no further! This article was written in an attempt to reliably answer some of the most frequently asked questions about snakes. You may utilize the "Table of Contents" below to help you quickly navigate to the section your particular snake-related question resides [by using your browser's "search" function (most often accessed by pressing "Ctrl+F" on your keyboard)]. The information presented herein is intended to be as accurate and succinct as possible, while providing some nice pictures and diagrams. Please see the "Disclaimer" section at the bottom of this page for more details on all of the content and materials presented here. If you believe that your snake question is not adequately addressed here or in the articles that I link to in my "Snake Venom" hub series, then please feel free to ask your question in the "Comments" section at the bottom of this article and I will do my best to answer it and add that question/information to this article. Also, if you believe that any of the information contained in this article is lacking sufficient detail or is incorrect, then please leave a detailed comment addressing the issue and citing your sources (web links, books, journal articles, etc.). Thank you, and enjoy!

Table of Contents

Hint: use your browser's "search" function (most often accessed by pressing "Ctrl+F" on your keyboard) to quickly navigate to the section your particular snake-related question resides.

  1. What is the taxonomy of snakes?
  2. What is the taxonomy of venomous snakes?
  3. What about snake physiology and growth?
  4. What about snake skin?
  5. What about snake senses?
  6. What about snake skeletal and organ systems?
  7. What about snake teeth?
  8. What about snake venom?
  9. What about snake ingestion, digestion, and excretion?
  10. What about snake tails?
  11. What about snake reproduction?
  12. How does a snake move?
  13. Is there a difference between a Boa Constrictor and a Python?
  14. What are some characteristics of vipers?
  15. How can I easily identify front-fanged venomous snakes in the United States?
  16. Which snake is the most "venomous?"
  17. What are some snake records?
  18. What are some myths and misconceptions about snakes?
  19. Why are snakes worth keeping around?
  20. Disclaimer

What is the taxonomy of snakes?

Here is the commonly accepted phylogenetic tree leading up to snakes, including amphibians, lizards, and mammals as reference points:

>Kingdom Animalia

<>Phylum Chordata

<>>Subphylum Vertebrata

<><>Class Amphibia (frogs/salamanders)

<><>Class Mammalia (mammals)

<><>Class Reptilia (reptiles)

<><>>Order Squamata

<><><>Suborder Lacertilia (lizards)

<><><>Suborder Serpentes (snakes, >2,900 species)

What is the taxonomy of venomous snakes?

There are over 1,200 species of snakes in the world that can be considered "venomous." These snakes are thought to have descended from a single, common ancestor with rear-fangs. Here is the taxonomic breakdown of the venomous snakes:

>Suborder Serpentes (snakes, >2,900 species)

<>Superfamily Colubroidea (advanced snakes, >1,200 species)

<>>Family Atractaspididae (all venomous)

<><>Examples: Burrowing Asps, Stiletto Snakes

<>>Family Colubridae (some nonvenomous)

<><>Examples: many "common/typical" backyard snakes (at least in the U.S.)

<>>Family Elapidae (all venomous)

<><>Examples: Cobras, Coral Snakes, Sea Snakes

<>>Family Viperidae (all venomous)

<><>Examples: Vipers, Rattlesnakes

Snakes Can Thrive in Deserts

Three Prairie Rattlesnakes (Crotalus viridis viridis) of various sizes/ages to illustrate how being cold-blooded permits these snakes to thrive in low-energy environments, such as deserts.
Three Prairie Rattlesnakes (Crotalus viridis viridis) of various sizes/ages to illustrate how being cold-blooded permits these snakes to thrive in low-energy environments, such as deserts.

Albino Corn Snake

A baby albino Corn Snake (Pantherophis guttatus), showing the red, white, and pink scale colors that accompany the red eyes.  This snake likely has reduced vision and physical performance, meaning that it would probably not survive in the wild.
A baby albino Corn Snake (Pantherophis guttatus), showing the red, white, and pink scale colors that accompany the red eyes. This snake likely has reduced vision and physical performance, meaning that it would probably not survive in the wild.

What about snake physiology and growth?

  • Are snakes cold-blooded? Yes, they are ectothermic (cold-blooded) creatures that must rely on their environment to regulate their body temperature (e.g., either basking in the sun to increase temperature or moving into the shade to decrease temperature). This makes them up to 100 times more energy efficient than endothermic (warm-blooded) animals, leaving more energy available for growing and reproducing. This grants snakes the ability to thrive in "low-energy" environments (such as deserts).
  • Are some snakes albino? Snakes are subject to many of the same color abnormalities (and the physical/mental handicaps that often accompany them) that several other organisms might experience as a result of random genetic mutations. This includes conditions such as albinism and melanism. Albino snakes are easily visible to predators and tend to have impaired eyesight and reduced motor/neural function, resulting in their very high mortality rate in the wild.
  • Do snakes ever stop growing? No, they continue growing throughout their lives. The rate of this growth depends upon the metabolism of the snake, which can vary drastically based on a wide variety of factors (food availability, reproduction, environment, health, stress, species, etc.).
  • How long do snakes live? Most species have a maximum (captive) lifespan of 15-25 years. Metabolism (not maximum size) directly impacts the lifespan of the snake, with lower metabolic rates (slower growth) resulting in longer lifespans. The process of "aging" is due to the accumulation of DNA damage and the shortening of telomeres (that protect the ends of chromosomes) with each cell replication (therefore, faster growth = faster degradation).

Snake
Snake

This book provides a nice summary of various snake-related topics.

 

Snake Skin Layers During Ecdysis

A cross-section of snake skin, showing the old, outer layer of scales in the process of being shed (with a layer of fluid separating it from the new, inner scale layer). Beneath the new scale layer is a layer of skin cells and a layer of stem cells.
A cross-section of snake skin, showing the old, outer layer of scales in the process of being shed (with a layer of fluid separating it from the new, inner scale layer). Beneath the new scale layer is a layer of skin cells and a layer of stem cells.

Keeled Scales and Anal Plate

Comparison of normal, smooth scales to scales that possess a ridge down the middle (keel) of varying strengths (weak-strong). The anal plate can either be intact or split and covers the cloaca, directly preceding the post-cloacal scales on the tail.
Comparison of normal, smooth scales to scales that possess a ridge down the middle (keel) of varying strengths (weak-strong). The anal plate can either be intact or split and covers the cloaca, directly preceding the post-cloacal scales on the tail.

Heavily Keeled Scales

Looking down along the top of a Prairie Rattlesnake (Crotalus viridis viridis), showing the heavily keeled scales on the dorsal side of the snake.
Looking down along the top of a Prairie Rattlesnake (Crotalus viridis viridis), showing the heavily keeled scales on the dorsal side of the snake.

What about snake skin?

  • Do snakes have skin? Yes, but their skin is covered and protected by a layer of scales.
  • What are snake scales? Scales are thickened, keratinized areas of skin that serve to protect the snake and help it retain water. There are two layers of keratin in the scales: a hard, outer layer of β-keratin (beta-keratin; composed primarily of β-sheets) and a softer, inner layer of α-keratin (alpha-keratin; composed primarily of α-helices, but containing some β-sheets).
  • Are there different kinds of snake scales? Yes, snakes can have scales that are smooth, "keeled" [where the scales possess a ridge down the center of the scale (much like the keel on the bottom of a boat)], or "granular" [where the scales are very 3-D and appear "bumpy" (like a hill) or pyramidal]. Keeled and granular scale morphologies give snakes a "rough" texture.
  • Do some snakes have "horns" or "hair?" A number of snake species possess modified scales that have a "horny" or "hairlike" appearance. For example, the Eyelash Viper (Bothriechis schlegelii) has specialized scales around the eyes which resemble eyelashes, whereas the Gaboon Viper (Bitis gabonica) has specialized scales atop the anterior end of its head which resemble horns. These specialized structures are not actually composed of hair or bone.
  • Are snakes slimy? To my knowledge, there are no snake species that secrete a mucous-like substance from their skin. Their skin may feel smooth or course (depending on the individual species and the morphology of the scales), but never slimy.
  • Do snakes shed their skin all in one piece? Yes, they shed their skin all at one time in a process called ecdysis. Once the snake has constructed a new, inner layer of scales (keratin), a fluid is excreted between the new and old layers of scales in order to separate them. This fluid is then re-absorbed and the snake sloughs off its old layer of skin in a single piece (provided the snake is healthy and under optimal environmental conditions).
  • Why do snake eyes turn blue before they shed? This occurs as a direct result of the fluid that is excreted by the snake to separate its new and old scale layers. This fluid makes the snake appear dull or bluish in color (greatly inhibiting their eyesight, making them more nervous/cautious) and more/less returns the snake to its normal color once it is reabsorbed (right before it actually sheds the old, outer scale layer). The excreted fluid, being composed of lactic acid and acid phosphatase, serves to hydrate and separate the layers by breaking apart the "glue" that holds the old and new scale layers together (e.g., desmosomes).

Different Kinds of Snake Eyes (Pupils)

Snakes most commonly have round pupils, horizontal pupils, or vertical pupils.  Vertical pupils can dilate to the point that they almost appear to be round.  Snake vision may be inhibited before shedding (having blue eyes) or by cataracts.
Snakes most commonly have round pupils, horizontal pupils, or vertical pupils. Vertical pupils can dilate to the point that they almost appear to be round. Snake vision may be inhibited before shedding (having blue eyes) or by cataracts.

Snake Senses

Various senses of this Northern Brown Snake (Storeria dekayi dekayi) are labeled, emphasizing its eye, nostril, mouth, forked tongue, and lack of an external ear.
Various senses of this Northern Brown Snake (Storeria dekayi dekayi) are labeled, emphasizing its eye, nostril, mouth, forked tongue, and lack of an external ear.

Binocular Vision in Snakes

Brown Vine Snakes (Oxybelis aeneus) are arboreal snakes that possess a slender snout and bulging, round eyes that permit a wide binocular field of view and enable the accurate acquisition of prey (namely birds and lizards).
Brown Vine Snakes (Oxybelis aeneus) are arboreal snakes that possess a slender snout and bulging, round eyes that permit a wide binocular field of view and enable the accurate acquisition of prey (namely birds and lizards).

Mouth Anatomy of a Viper

A Gaboon Viper (Bitis gabonica) swallowing a House Mouse (Mus musculus), emphasizing the folded up front-fangs, extended trachea, "horns," nostril, and the mouth roof openings to the nostrils and Jacobson's organ.
A Gaboon Viper (Bitis gabonica) swallowing a House Mouse (Mus musculus), emphasizing the folded up front-fangs, extended trachea, "horns," nostril, and the mouth roof openings to the nostrils and Jacobson's organ.

What about snake senses?

  • Do snakes have good eyesight? They can have a highly variable sense of sight, with arboreal (tree-living) species tending to have great binocular vision and fossorial (burrowing) species commonly having poor vision.
  • Do snakes have eyelids? No, instead of having eyelids, their eyes are covered by a transparent scale (called a brille) that is replaced every time the snake sheds. This characteristic enables one to easily distinguish a legless lizard from a snake, due to the fact that all lizards (except geckos) have eyelids.
  • Are snake eyes like human eyes? No, their eyes have re-evolved such that the lens is physically moved (by the iris muscles) to change focus, as opposed to all other tetrapods changing the curvature of the lens (using ciliary muscles, which are lacking in snakes) to accommodate. Snake eyes were "lost" in their fossorial ancestors (eyes are virtually useless underground) and secondarily re-evolved for returning to a terrestrial lifestyle.
  • Can snakes see heat? Some snake species have heat-sensing pits or vents, which are capable of detecting less than a 0.01 degree Fahrenheit difference in temperature. These heat-sensitive organs couple with their eyesight and sense of smell (forked tongue) in order to get a very precise direction and distance to their target.
  • Do snakes have a good sense of smell? Although snakes have nostrils, they are granted a great sense of smell due to the action of their forked tongues, which "taste" the air. Each fork of the tongue is inserted into a different chamber of the Jacobson's organ in the roof of the mouth. This allows the snake to pick up scent particles in the air in a direction- and concentration-dependent fashion, which tells the snake where and how far its target is.
  • Do snakes have ears? No, they lack external or middle ears, giving them a poor sense of hearing. They do, however, have inner ears that enable them to sense vibrations through the air or substrate using bone conduction.

What does a snake skeleton look like?

A Garter Snake (Thamnophis sirtalis) skeleton, emphasizing the different sections of the snake as well as the ribs and vertebrae. The skull has been removed to focus on the neck vertebrae. This ~3' long snake has 226 vertebrae and ~350 ribs.
A Garter Snake (Thamnophis sirtalis) skeleton, emphasizing the different sections of the snake as well as the ribs and vertebrae. The skull has been removed to focus on the neck vertebrae. This ~3' long snake has 226 vertebrae and ~350 ribs.
Snakes: The Evolution of Mystery in Nature
Snakes: The Evolution of Mystery in Nature

This book covers many different aspects of snakes in great detail.

 

Snake Internal Anatomy

Snakes possess many of the same vital organs that humans have, with a couple of important exceptions. Snakes have elongated organs, 3-chambered hearts, and lack a diaphragm. This is a female ~2.5' long Garter Snake (genus Thamnophis).
Snakes possess many of the same vital organs that humans have, with a couple of important exceptions. Snakes have elongated organs, 3-chambered hearts, and lack a diaphragm. This is a female ~2.5' long Garter Snake (genus Thamnophis).

What about snake skeletal and organ systems?

  • Do snakes have bones? Yes, snakes are vertebrates. A snake’s skeleton is principally composed of a skull, ribs (as many as 500 in some species), and highly flexible vertebrae [most of which are connected to two ribs, all the way back to the region of the cloaca (caudal/post-cloacal vertebrae are either devoid of ribs or have small ribs for a short distance from the cloaca)].
  • Do snakes have legs? Although most snake species lack hindlimbs and a pelvic girdle, all snakes lack forelimbs and a pectoral girdle. Some of the more "archaic" species of snakes (such as pythons, boas, and blind snakes) possess a pelvis and vestigial remnants of femurs (commonly in the form of anal/pelvic/cloacal spurs, which protrude from either side of the cloaca). Having reduced/absent limbs is not unique to snakes, but has actually evolved at least 62 independent times in members of Order Squamata (snakes and lizards), with ~25 times occurring in Skinks, alone.
  • What internal organs do snakes have? They have many of the same organs that humans possess, such as a stomach, liver (often the largest organ), lungs, kidneys, adrenal glands, spleen, pancreas, intestines, gall bladder, gonads, and a thyroid gland. They have three-chambered hearts (two atria and one ventricle) and lack a diaphragm (relying on body action to pump air in and out). Their vital organs have become long and slender in order to comfortably fit in their tube-like bodies.
  • Do snakes only have one lung? Depending on the species involved, the left lung tends to be reduced in size or absent, with an enlarged right lung. Some of the “archaic” snakes (such as pythons and boas) have two functional lungs, whereas some of the “advanced” snakes (such as rattlesnakes) only have one lung. This is another way to tell legless lizards from snakes, as they have evolved to “prefer” their left lung, with a reduced/absent right lung.

Subpleurodont Dentition

Snakes have subpleurodont dentition, where the teeth reside in a theca (small pocket) bordered on the labial side by a large bony ridge (pleura) and bordered on the lingual side by a small bony ridge.
Snakes have subpleurodont dentition, where the teeth reside in a theca (small pocket) bordered on the labial side by a large bony ridge (pleura) and bordered on the lingual side by a small bony ridge.

What about snake teeth?

  • What kind of teeth do snakes have? They have needle-like (long, slender) independent teeth (teeth that are not connected to other teeth; like in humans) that are slightly curved inward and replaced continuously throughout their lives. Snakes have subpleurodont dentition, meaning that their teeth are attached to a large ridge (called a pleura) of the jawbone on the labial side (facing the lips/cheek) and are attached to a low bony ridge at the base on the lingual side (facing the tongue). This bone arrangement forms a shallow pocket (called a theca) that each tooth rests inside of.
  • Are all snake teeth the same? It depends on whether or not they are venomous. Snake teeth are either homodont (all teeth are similar in size, shape, and function) or heterodont (possessing a pair of specialized "fangs" for injecting venom), depending on the species.
  • What are snake fangs? Fangs are specialized teeth designed to introduce venom into prey and predators. You may refer to the following article, which discusses the topic in some detail: Snake Fangs 101.

Cobra Fangs: Normal vs Spitters

Front-view comparison between "normal" Cobra fangs and Spitting Cobra fangs, showing the long, shallow, roughly diamond-shaped exit orifices for the venom of "normal"  Cobras and the roughly "circular" exit orifices for the venom of Spitting Cobras.
Front-view comparison between "normal" Cobra fangs and Spitting Cobra fangs, showing the long, shallow, roughly diamond-shaped exit orifices for the venom of "normal" Cobras and the roughly "circular" exit orifices for the venom of Spitting Cobras.

Venom Injection by Front-fang

A Prairie Rattlesnake (Crotalus viridis viridis) using its front-fangs to inject venom into the neck of an already dead Tree Lizard (Urosaurus ornatus). The snake's eye, heat-sensing pit, front-fangs, and trachea are emphasized.
A Prairie Rattlesnake (Crotalus viridis viridis) using its front-fangs to inject venom into the neck of an already dead Tree Lizard (Urosaurus ornatus). The snake's eye, heat-sensing pit, front-fangs, and trachea are emphasized.

Venom Injection by Rear-fang

A Night Snake (Hypsiglena torquata) using its rear-fangs to inject venom into the body of a live pinkie House Mouse (Mus musculus).  The snake's dilated vertical pupil, rear-fang, and stretched skin are emphasized.
A Night Snake (Hypsiglena torquata) using its rear-fangs to inject venom into the body of a live pinkie House Mouse (Mus musculus). The snake's dilated vertical pupil, rear-fang, and stretched skin are emphasized.

What about snake venom?

  • What is in snake venom and what envenomation symptoms might be caused by snakebite? Snake venom can be surprisingly variable, so it can be difficult to predict exactly what compounds are present in it and what effects a human may suffer from an envenomation. You may refer to the following article, which discusses these topics in some detail: Snake Venom Composition/Variability.
  • Can snakes “spit” their venom? Only around 16 species of snakes can manage this feat with some level of proficiency, with the ability to spit having evolved independently on at least three occasions. Several Cobras (genus Naja) and the Rinkhals (genus Hemachatus) have specialized fangs with a forward-facing (instead of downward) venom exit hole. This exit hole is higher up on the fang (not reaching down to the tip), closer to the center face of the fang (instead of off to the side), circular/tear-shaped (instead of diamond/oval-shaped), rifled (to increase accuracy/range), and angled “inward” towards the center line of the snake’s head (such that the ejected venom streams from each fang cross over at a certain distance). Some of the more proficient spitters are capable of ejecting a surprisingly accurate venom spray (targeted at the eyes/face) up to a distance of 10 ft away. The snake may attempt to modulate how much air is expelled during spitting in order to adjust the spread of the aerosolized spray to the size of the face. Once in the eyes, the venom is capable of causing extreme pain and blindness. The Mangshan Pitviper (Protobothrops mangshanensis) is reported to have some ability to “spit” venom, but this has not been scientifically verified and could just be the result of loose venom droplets being propelled forward by the snake’s forcefully exhaled air during a hiss.
  • Are rear-fanged snakes dangerous? Most species of rear-fanged snakes are relatively harmless to people because their venoms are not typically dangerous towards humans and they are incapable of effectively injecting large quantities of venom in a bite (without holding on for a significant period of time). The following article discusses this topic in detail: Front- and Rear-fanged Snake Envenomation Systems.

Handbook of Venoms and Toxins of Reptiles
Handbook of Venoms and Toxins of Reptiles

This book focuses on the toxic aspects of snakes, namely venomous ones.

 

Some Snakes Eat Other Snakes

A Sonoran Coral Snake (Micruroides euryxanthus) eating a Long-nosed Snake (Rhinocheilus lecontei), which was just slightly smaller than the Coral Snake.
A Sonoran Coral Snake (Micruroides euryxanthus) eating a Long-nosed Snake (Rhinocheilus lecontei), which was just slightly smaller than the Coral Snake.

Prey Handling: Constriction

A Banded Flying Snake (Chrysopelea pelias) constricting around a fuzzy House Mouse (Mus musculus) to try to kill it before ingesting it.  This snake has cataracts.
A Banded Flying Snake (Chrysopelea pelias) constricting around a fuzzy House Mouse (Mus musculus) to try to kill it before ingesting it. This snake has cataracts.

Prey Handling: Live Consumption

A Western Hognose Snake (Heterodon nasicus) swallowing a live pinkie House Mouse (Mus musculus).  Pinkie mice are often recognized by snakes to be harmless prey that can be safely procured in its native state.
A Western Hognose Snake (Heterodon nasicus) swallowing a live pinkie House Mouse (Mus musculus). Pinkie mice are often recognized by snakes to be harmless prey that can be safely procured in its native state.

Snake Gape Size

The wide-open mouth of a Prairie Rattlesnake (Crotalus viridis viridis), showing a ~100 degree gape that helps it ingest large prey items, whole.
The wide-open mouth of a Prairie Rattlesnake (Crotalus viridis viridis), showing a ~100 degree gape that helps it ingest large prey items, whole.

What about snake ingestion, digestion, and excretion?

  • What do snakes eat? They are carnivorous and ingest other creatures (preferably alive or freshly killed). They can acquire prey by constricting (wrapping around them and squeezing), injecting venom, simply overpowering them, or a mix of all three. Snakes are capable of digesting virtually anything but hair (which is occasionally excreted in the form of "hairballs" along with the "normal" waste). Many snakes are capable of eating other snakes and some species even specialize in such behavior (these snakes are often called Kingsnakes).
  • Do snakes chew their food? No, snakes ingest prey whole without chewing to break it into smaller pieces first. Snake teeth are designed to grab and hold onto prey until it is swallowed, not chew.
  • Can snakes consume eggs? Some species are capable of swallowing eggs. A few species even possess a vertebral projection in their esophagus that enables the snake to crack the eggshell in their throat, squeeze the contents out into their stomach, and then regurgitate the leftover bits of shell.
  • How do snakes breathe while swallowing large prey? The anterior portion of the trachea, which resides along the bottom of the mouth/throat, is very strong/mobile and may be extended out of the mouth, beneath the prey being swallowed, to facilitate breathing during ingestion (which, in the case of very large constrictors, is a process that may take over an hour).
  • How far can snakes open their mouths? They tend to have highly kinetic skulls (up to 150 degree opening) for swallowing large prey whole. Fossorial snakes, however, tend to have much more rigid skulls that cannot open very far. Most snakes have highly flexible lower jaws (due to the fact the left and right lower jawbones are often not connected) and very stretchable skin, enabling them to effectively wrap their mouths around large prey.
  • Do snakes always eat their prey head-first? Generally, yes. This is because the bodies of most animals are oriented in a head-to-tail fashion, meaning that swallowing prey in that manner will permit everything to go down the snake's throat much smoother. Their forked tongue helps them locate the mouth of incapacitated prey so that they can ingest them head-first.
  • Where and how do snakes poop? They possess a cloaca for excreting waste in the form of uric acid (and, on occasion, bits of undigested hair in the form of "hairballs"). The cloaca is a unified orifice for excreting both solid and liquid waste. It is oriented in a transverse fashion (not longitudinal, like in most tetrapods), meaning that if you were to pick up a snake from the head (allowing its body to dangle straight down) and look at the underside of its tail, the cloacal opening would be horizontal. The cloaca is covered by a specialized, half-moon-shaped scale called the anal plate (which can be single/intact or divided, depending on the species). Uric acid is an efficient form of solid waste that reduces water loss. The amount of liquid (urine) excreted with the uric acid varies between species.

What does snake poop look like?

This is a large load of solid waste excreted by a 4' long Ball Python (Python regius), with the uric acid pellets circled in red and the brown "hairballs" (undigested rat hair).  Snakes tend to "store" hairballs and only excrete them every so often.
This is a large load of solid waste excreted by a 4' long Ball Python (Python regius), with the uric acid pellets circled in red and the brown "hairballs" (undigested rat hair). Snakes tend to "store" hairballs and only excrete them every so often.

Intact and Broken-off Rattles

Comparing a rattle that a snake has retained since birth (with its rounded, terminal button) to a rattle that a snake has broken off at least once (with its rough, terminal rattle segment). The intact rattle is 7 rattles long (plus the button; b+7).
Comparing a rattle that a snake has retained since birth (with its rounded, terminal button) to a rattle that a snake has broken off at least once (with its rough, terminal rattle segment). The intact rattle is 7 rattles long (plus the button; b+7).

What about snake tails?

  • What is considered the "tail" of a snake? The tail is the portion of the body from the cloaca to the end of the snake. Tail length varies based on species (and gender in some species) and total body length. Whereas legless lizards nearly always have long tails (most vertebrae are post-cloacal), snakes often have short tails (most vertebrae are pre-cloacal). Ventral scales on the tail are called post-cloacal or caudal scales and can either be single/intact (one scale row) or divided (two scale rows).
  • Can snakes re-grow their tails? They tend to be capable of losing their tails with twisting and force (a process called pseudautotomy, where the tail breaks in between the vertebrae and is not under conscious control of the snake), but aren't capable of regenerating them.
  • What is a snake rattle? Rattles are constructed of a series of interlocking segments of keratin (often referred to as "rattles"), located at the end of a Rattlesnake's tail. Rattlesnakes are the only snakes to have this unique adaptation, which they vibrate vigorously (at a muscle twitch rate faster than any other vertebrate) to ward off potential predators. Rattlesnakes are strictly limited to the Americas. A single rattle segment is added each time the snake sheds by making a "cast" inside of the button (i.e., basal rattle) at the end of the tail.
  • Can you tell the age of a snake by the size of its rattle? Not necessarily. Rattles can be relatively fragile and break off with some frequency. The rate at which a rattle grows in size (number of segments) is dependent upon how often the snake is shedding, which primarily relies on the snake’s age, health, and feeding frequency. Snakes can shed approximately 8 times a year during their first year of life, but may slow down to less than half of that during their adult life. You can, however, determine if a snake has lost/damaged its rattle since birth by looking for an intact "terminal button" on the end of the rattle.
  • Do snakes secrete musk? Many snakes have musk glands and are capable of excreting a smelly fluid (called musk) from their cloaca in order to ward off predators. Some species (e.g., Rattlesnakes) can even aerosolize concentrated musk a couple of feet away in a manner similar to a skunk.
  • Do snakes secrete pheromones? Some species are known to produce pheromones in their skin or from scent glands in their tail for use in communication and reproduction.

Snake Parental Care

A ~4.5' Ball Python (Python regius) curling around her 9 leathery eggs (that are nearly chicken egg-sized) to warm and protect them.  The two orange-colored eggs off to the side were "duds" (infertile/"stillborn") that did not develop normally.
A ~4.5' Ball Python (Python regius) curling around her 9 leathery eggs (that are nearly chicken egg-sized) to warm and protect them. The two orange-colored eggs off to the side were "duds" (infertile/"stillborn") that did not develop normally.

Tail of a Male Snake

Male snakes have hemipenes, which are a pair of copulatory organs that exist as an outpocketing near the end of the cloaca.  The ribs stop around the cloaca, which is where the tail of a snake officially begins.
Male snakes have hemipenes, which are a pair of copulatory organs that exist as an outpocketing near the end of the cloaca. The ribs stop around the cloaca, which is where the tail of a snake officially begins.

Male versus Female Tail Length

Comparing tail length in a sexually dimorphic species (Ball Pythons, Python regius), where a ~3 lb male snake possesses only a slightly shorter tail than a female snake twice its weight.  Male Ball Pythons grow longer tails than females.
Comparing tail length in a sexually dimorphic species (Ball Pythons, Python regius), where a ~3 lb male snake possesses only a slightly shorter tail than a female snake twice its weight. Male Ball Pythons grow longer tails than females.

What about snake reproduction?

  • Do any snakes show parental care? A few species do. Rattlesnake mothers may care for their young (defend, roundup, etc.) up until the babies shed for the first time. Some python mothers are known to wrap around their eggs to protect and incubate them (by “shivering” their muscles to create heat) until they hatch. King Cobra (Ophiophagus hannah) mothers are actually known to create a mound, or "nest," of decaying matter to incubate their eggs. King Cobra mothers will often aggressively defend their nest until a couple of days before the eggs hatch (supposedly to prevent the mother from eating the babies, as King Cobras are cannibalistic). Most snake species, however, demonstrate minimal, if any, parental care.
  • Do snakes lay eggs or have live young? Depending upon the species, snakes can either be oviparous (lay leathery eggs) or ovoviviparous (retain eggs until they "hatch" inside of the mother and the live young are "birthed").
  • Does temperature determine whether snake babies are male or female? No, their gender is genetically determined (not temperature-dependent as in Crocodilians). Males have ZZ chromosomes (as opposed to XY in humans) and females have ZW chromosomes (as opposed to XX in humans).
  • Is it possible for a snake to reproduce by itself? Although snakes tend to utilize sexual reproduction, certain species/populations/individuals may undergo asexual reproduction via parthenogenesis. This means that a female snake can have a "virgin birth" by way of creating half-clones of herself (due to a mistake during oogenesis, whereby a polar body can act as a sperm and fertilize the egg). This is the only way that female offspring with WW chromosomes can be created in nominal amounts.
  • Do male snakes have a penis? Well, actually, male snakes have a pair of copulatory organs called hemipenes. These hemipenes are basically outpocketings of the end of the cloaca (within the tail) that are everted from the cloaca before copulation. The fine structure (spines, ridges, and ornamentation) of these hemipenes is often used as an "easy" way of identifying a species, as it tends to have a higher rate of evolution than many other physical traits. Males only insert one of their hemipenes into the female snake's cloaca at a time, where a groove in the surface of the hemipenis (called the sulcus spermaticus) transports sperm into the female.
  • Is there an easy way to tell a male snake from a female snake? Some species are sexually dimorphic, where the males possess longer tails (relative to total body length), a different body coloration than the females (e.g., Boomslang males are green, whereas females are brown), or don't grow to be as large as females. In species that possess cloacal spurs, males possess larger and more mobile cloacal spurs than females. Males also tend to have tails that taper slowly (due to the presence of the hemipenes), whereas females have tails that taper quickly. In many cases, however, the only way to tell for sure is by “probing” the animal [with the probe traveling much further down the tail in males (within the hemipenal pocket) than in females (e.g., traveling 10 scales in males and 2 scales in females)].

A Snake that "Flies"

This Paradise Flying Snake (Chrysopelea paradisi) has the capacity to safely glide through the air when "leaping" from tall trees.  Here you can see the unusual underbelly, which becomes concave upon lift-off, forming an air-foil.
This Paradise Flying Snake (Chrysopelea paradisi) has the capacity to safely glide through the air when "leaping" from tall trees. Here you can see the unusual underbelly, which becomes concave upon lift-off, forming an air-foil.

How does a snake move?

Snakes can move a variety of ways, dependent upon the species, substrate, and the individual snake's needs at the time. The following are seven common ways that snakes can move, preceded by the questions that one might ask when seeking knowledge of that particular mode of locomotion.

  • How do snakes "normally" move? Can snakes swim? Lateral Undulation: When crawling on a substrate with objects in the environment, snakes will tend to move using lateral undulation, also known as serpentine locomotion, which is the "typical," s-shaped way for snakes to move. This consists of the snake not only pushing off of the ground beneath its body, but also pushing off of the sides of the objects in its environment, giving the snake increased speed and agility (often granting it the ability to out-maneuver humans and other potential predators). To clarify, this process involves the snake pushing posterolaterally off a variety of pivot points in the environment in order to move forward in a continuous manner (with no recovery phase). Lateral undulation is also commonly utilized while the snake is swimming in water. This mode of locomotion does not involve any static points of contact with the substrate.
  • Can snakes move on a smooth, solid surface like glass? Slide-pushing: While crawling on low-friction substrates, snakes can utilize slide-pushing. This consists of the snake using rapid, alternating waves of body motion to generate a "sliding friction" that propels the snake forward. To clarify, this process involves the snake using seemingly non-productive movements to "flail" itself forward on a slippery substrate. This mode of locomotion does not involve any static points of contact with the substrate.
  • Can snakes move in a straight line? Rectilinear: While crawling on a stable substrate devoid of objects, snakes will tend to move using rectilinear locomotion, also known as "rib-walking." This consists of the snake using its ribs and associated muscles to push itself up off of the ground and forward in a more-or-less straight line (making it appear as though the ribs are "walking" when seen from the side, almost like an inchworm). To clarify, this process operates on a small scale whereby the snake pulls its skin forward and then brings the ribs and body up to the skin using the ventral scales as a stationary anchor. This is the only mode of snake locomotion to use synchronous muscle contractions and involves several points of static contact with the substrate. This locomotion is most commonly seen in large, heavy-bodied snakes.
  • Can snakes climb trees? Concertina: When attempting to climb up a tree or move across a low-friction surface, snakes will often utilize concertina locomotion, which is similar to the movement of an accordion. This consists of the snake reaching its head and neck up the tree to start wrapping around it, getting a firm wrap using the front portion of its body, then bringing up the rest of its body, loosening up the front portion while tightening the back portion of its body, and reaching up to the next point and repeating the process (hence, going from a spread-out state to a bunched-up state, like an accordion). To clarify, this process involves the snake establishing a stable platform with the front part of its body, then bringing up the rest of its body to establish another stable platform, enabling the front part of the body to release and extend to establish another platform. This mode of locomotion involves static points of contact with the substrate. Concertina locomotion is slow-going and energetically costly (requiring up to 7 times more energy than lateral undulation).
  • How do snakes move across sand? Sidewinding: While crawling on a low-friction or shifting substrate devoid of objects, snakes will tend to move using sidewinder locomotion. This is a complicated motion whereby the snake utilizes its own momentum to propel itself forward using a series of lateral "body throws" (in the form of “loops”) initiated by the head/neck and followed through by the body, resulting in the appearance of a series of independent (not connected), s-shaped "footprints" in the substrate (which are oriented at an angle to the net direction of motion). To clarify, this process involves the snake applying force in a predominantly downward fashion (to avoid slipping) to lift a portion of its body, move it forward, and set it down (making it appear as though the snake is wildly throwing body loops angled to the side at random). This mode of locomotion tends to involve static contact with the substrate at two points and can be utilized by a number of species of snakes (not just Sidewinder Rattlesnakes).
  • Can snakes jump? Saltation: When a snake needs to cross a distance quickly, it may opt to use saltation (jumping). This is basically a modified form of concertina locomotion, where the snake rapidly straightens its body in an anterior to posterior fashion while lifting its entire body off of the substrate. To clarify, this process consists of the snake jumping (or faux striking) and throwing its entire body forward, lead by its head. Saltation is a rare form of locomotion that is primarily utilized in aggressive or escape behavior. This mode of locomotion involves static points of contact with the substrate.
  • Can snakes fly? Gliding: Constrained to a select few species, these snakes are capable of a limited form of flight called "gliding." This is where the snake "leaps" from atop a tall object (e.g., tree) and glides safely down to the ground (typically traveling much further laterally than vertically). To clarify, this process consists of the snake "jumping" off of the tall object (to "catch" the air), making its belly concave (instead of convex) to create an air-foil (similar to a plane wing or parachute), moving its body in a way similar to lateral undulation (to propel the snake forward), and using its tail as a rudder to direct its final trajectory (on the ground or another tree).

Cloacal Spurs

Many boids possess remnants of rear-legs (femurs) in the form of cloacal spurs that border the sides of the anal plate (and the cloaca, underneath).  The post-cloacal scales are divided in this Ball Python (Python regius).
Many boids possess remnants of rear-legs (femurs) in the form of cloacal spurs that border the sides of the anal plate (and the cloaca, underneath). The post-cloacal scales are divided in this Ball Python (Python regius).

Heat Vents in Pythons

A Ball Python (Python regius), emphasizing its heat-sensitive vents, which are located within its labial scales. Boa Constrictors, on the other hand, possess heat vents between the labial scales. This snake is swallowing the last bits of a rat.
A Ball Python (Python regius), emphasizing its heat-sensitive vents, which are located within its labial scales. Boa Constrictors, on the other hand, possess heat vents between the labial scales. This snake is swallowing the last bits of a rat.

Dorsal Head Scales

Comparing the number of dorsal head scales between the eyes of a Ball Python (Python regius) and a Red-tail Boa Constrictor (Boa constrictor constrictor).  Boa Constrictors have significantly smaller dorsal head scales than Pythons.
Comparing the number of dorsal head scales between the eyes of a Ball Python (Python regius) and a Red-tail Boa Constrictor (Boa constrictor constrictor). Boa Constrictors have significantly smaller dorsal head scales than Pythons.

Is there a difference between a Boa Constrictor and a Python?

Yes, there are several differences between them. We will go on to evaluate and present both similarities and differences between boas and pythons.

  • Are boas and pythons the same? No. Although they are both part of family Boidae, they comprise different subfamilies. Boinae is the subfamily of Boa Constrictors, Erycinae is the subfamily of Sand Boas, and Pythoninae is the subfamily of Pythons (Note: although the taxonomy of these snakes has changed in recent years, it is most convenient to utilize this older phylogeny in order to adequately compare their characteristics as presented here).
  • Are boas and pythons constrictors? Yes. All members of family Boidae are capable of using their body muscles to constrict their prey. Constriction is used to suffocate and/or crush prey in order to overpower/incapacitate/kill them before safely ingesting them.
  • Do boas and pythons have cloacal spurs? Several species of snakes within family Boidae possess the remnants of femurs and a pelvis. These cloacal spurs, larger in males than in females, are often used by male snakes to “tickle” the female snake into a position that is conducive to copulation and are sometimes utilized in male-male combat.
  • Do boas and pythons lay eggs? Although pythons are oviparous (lay eggs), boas are ovoviviparous (give birth to live young).
  • Do boas and pythons have heat receptors? Many species (except for the Sand and Rubber Boas) possess heat-sensing vents on their upper/lower labial scales. They are recessed from the scales around them and can be a variety of colors (red to pink to grey). Although the labial vents in Boa Constrictors are located between the scales (commonly oriented along the side of the labial scales), the labial vents in Pythons are located within the scales (commonly oriented along the top of the labial scales).
  • Do boas and pythons have the same-sized scales in the front half of the top of their heads? No. Pythons have large dorsal head scales, whereas Boa Constrictors have small dorsal head scales, and Sand Boas possess intermediate-sized dorsal head scales. Although this is kind of relative, if you were to count the number of scales between the eyes, you would only count ~4 scales between the eyes of adult Pythons, and ~20 scales between the eyes of adult Boa Constrictors (meaning that Python head scales can be about five times as large as those of Boa Constrictors).
  • Can boas and pythons be found in the same areas of the world? Yes. Although North America only has Sand Boas, Central/South America only has Boa Constrictors, Europe only has Sand Boas, Australia and Southeast Asia only have Pythons, Africa, Indonesia, and the rest of Asia have a mixture of the three subfamilies.

Heat-sensing Pit Organ Anatomy

The internal anatomy of a heat-sensing pit organ (in Pitvipers), showing the opening to the external environment and the outer/inner air-filled chambers separated by the heat-sensing membrane.  This membrane reflects camera flash.
The internal anatomy of a heat-sensing pit organ (in Pitvipers), showing the opening to the external environment and the outer/inner air-filled chambers separated by the heat-sensing membrane. This membrane reflects camera flash.

Pitviper Heat Pits vs Nostrils

A front-view and a side-view of a Prairie Rattlesnake (Crotalus viridis viridis), showing how the heat-sensing pits face forward and are located in between and below the eyes and nostrils (which open laterally and are hardly visible from the front).
A front-view and a side-view of a Prairie Rattlesnake (Crotalus viridis viridis), showing how the heat-sensing pits face forward and are located in between and below the eyes and nostrils (which open laterally and are hardly visible from the front).

What are some characteristics of vipers?

  • What snakes are considered “vipers?” All members of family Viperidae, including the Old World Vipers (2 subfamilies, notably Viperinae), Pitvipers (subfamily Crotalinae), and Rattlesnakes (genera Crotalus and Sistrurus within subfamily Crotalinae).
  • Do all vipers have folding fangs? Yes, they all possess long front-fangs that fold up along the roof of their mouth when not in use (due to a rotatable maxilla).
  • Do vipers have hemotoxic venom instead of the neurotoxic venom of elapids? Venom composition is not as "cut-and-dry" as that due to the fact that several vipers possess “neurotoxins” and several elapids possess “hemotoxins.”
  • Are adders vipers? Although many adders, such as the European Adder (Vipera berus) are vipers, Death Adders (genus Acanthophis) are actually elapids that have undergone convergent evolution to act, look, and possess physiology similar to, a viper. This means that Death Adders are ambush predators with thick bodies, arrow-shaped heads, vertical pupils, and fangs that have evolved to become surprisingly long and mobile.
  • Do vipers lay eggs or have live young? They can either lay eggs (oviparous) or bear live young (ovoviviparous). All Rattlesnakes have live young.
  • Can vipers see heat? Pitvipers are named because they possess forward-facing heat-sensitive pits between their eyes and nostrils. Rattlesnakes, being a subset of Pitvipers, possess these pits, but Old World Vipers lack heat-sensitive pits.
  • Which state has the most venomous snakes? Arizona exhibits the most taxa (species and subspecies) of front-fanged venomous snakes in the U.S., having 19 snakes, all but one of which are rattlesnakes.

How to ID Coral Snakes in U.S.

Comparing deadly Coral Snake and harmless Kingsnake color-ring patterns.  The yellow color may, on occasion, be substituted for a white color.  These generalizations do not account for the very rare "mutant" snake.
Comparing deadly Coral Snake and harmless Kingsnake color-ring patterns. The yellow color may, on occasion, be substituted for a white color. These generalizations do not account for the very rare "mutant" snake.

Iconic American Venomous Snake

A Prairie Rattlesnake (Crotalus viridis viridis), which is the ideal candidate for these five quick-and-dirty rules for identifying Pitvipers in the United States.  Rattlesnakes are limited in distribution to the Americas.
A Prairie Rattlesnake (Crotalus viridis viridis), which is the ideal candidate for these five quick-and-dirty rules for identifying Pitvipers in the United States. Rattlesnakes are limited in distribution to the Americas.

How can I easily identify front-fanged venomous snakes in the United States?

The U.S. has only a couple of species of elapids, all being Coral Snakes (genera Micrurus and Micruroides). Although a few species of king- and milk-snakes mimic the colors and patterns of Coral Snakes, there is a relatively easy way to ID Coral Snakes (in the U.S.) based on the arrangement of colored rings on the snake’s body: If red touches black, venom lack (is a nonvenomous king/milk-snake), but if red touches yellow, it kills a fellow (is a venomous Coral Snake). In many of these snake species (venomous or harmless), yellow-colored rings are actually white.

In order to help ID vipers in the U.S., the following “rules” are presented. Note that these rules are most effective for ID’ing Rattlesnakes, slightly less effective for ID’ing Pitvipers (because they lack a rattle at the end of their tail), and are not at all effective at ID’ing Coral Snakes. All “rules” possess exceptions, but generally serve as a quick-and-easy guide to identifying vipers.

  • Does the snake have a rattle? All rattlesnakes (genera Crotalus and Sistrurus) are venomous and have a distribution limited to the Americas. Many non-rattlesnakes are capable of rapidly shaking their tail against the ground (preferably dead leaves or dry substrate) in an effort to imitate a “rattling” sound and mimic rattlesnake behavior in order to intimidate/warn predators. In addition, it is possible that the snake may have lost the end of its tail by an injury or may not have been born with a rattle as the result of a genetic defect.
  • Does the snake have an arrow-shaped head? An arrow-shaped head generally stems from two things: venom glands and jaw muscles. Vipers have large venom glands on the sides of their heads. Vipers also commonly have the ability to strike quickly and with a lot of force, which is partially derived from their large jaw muscles (some of which are associated with the venom glands). Many non-vipers have the capacity to flatten-out their heads in an effort to make them appear larger and more intimidating to potential predators.
  • Does the snake have vertical pupils? All rattlesnakes and vipers have vertical pupils, but there are also a few rear-fanged venomous (~harmless) snakes that have them [e.g., Night Snakes (Hypsiglena torquata) and Lyre Snakes (Trimorphodon biscutatus)]. Although vertical pupils tend to be found in snakes with nocturnal activity, they are more strongly associated with the hunting behavior of the snake (being found more often in sit-and-wait ambush predators). Vertical pupils permit the snake to keep a wide horizontal field in focus without having to move its head and give away its position. This is a trait that has evolved independently several times in many different groups of snakes and may aid in camouflage (by mimicking grass) and reduce the amount of glare in daylight. The caveat is that vertical pupils have the capacity to enlarge in darkness (in order to allow more light to enter the eye) to such a degree that they can appear to be round pupils.
  • Does the snake have heat-sensitive pits? All vipers in the U.S. are Pitvipers, so they will be the only snakes with a pair of forward-facing heat-sensitive pits located between the eyes and nostrils. Nostrils can be distinguished from heat pits because they are often lateral-facing (making them difficult to see from the front), not reflective when a light is shined upon them, positioned at the end of the nose, and smaller than heat pits.
  • Does the snake have a single row of post-cloacal scales? All U.S. vipers have intact ventral scales on the underside of the tail (a single row of post-cloacal scales), whereas any other snake (except for elapids) has divided ventral scales on the underside of the tail (two rows of post-cloacal scales).

Taking all of these things into account means that only some of these "guidelines" are truly reliable in easily identifying rattlesnakes: the presence of a rattle, heat-sensitive pits, and a single row of post-cloacal scales. Vertical pupils and an arrow-shaped head are characteristics that are often too relative and/or subjective to be useful.

How to Quickly/Easily ID Pitvipers in the U.S.

A set of five general rules/guidelines that serve as an easy reference tool for quickly identifying Pitvipers in the United States.  Keep in mind that only Rattlesnakes will possess a rattle at the end of their tail.
A set of five general rules/guidelines that serve as an easy reference tool for quickly identifying Pitvipers in the United States. Keep in mind that only Rattlesnakes will possess a rattle at the end of their tail.

Black Mouth Color for Defense

A Brown Vine Snake (Oxybelis aeneus) showing off the black lining in its mouth in a defensive display.  This is an example of convergent evolution with the one of the world's most effective human killers: the Black Mamba (Dendroaspis polylepis).
A Brown Vine Snake (Oxybelis aeneus) showing off the black lining in its mouth in a defensive display. This is an example of convergent evolution with the one of the world's most effective human killers: the Black Mamba (Dendroaspis polylepis).

Snake with Largest Fangs and Most Venom

The Gaboon Viper (Bitis gabonica) is known to grow the world's largest snake fangs (as long as 2.2") and produce the most snake venom, with as much as 9.7 ml of venom (2.4 kg of dried venom) from a single individual.
The Gaboon Viper (Bitis gabonica) is known to grow the world's largest snake fangs (as long as 2.2") and produce the most snake venom, with as much as 9.7 ml of venom (2.4 kg of dried venom) from a single individual.

Which snake is the most “venomous?”

This is a very broad/complicated question, so we will break it down into several specific questions, instead. All of the world’s most dangerous snakes are front-fanged venomous.

  • Which snake kills the most people? This is likely the Saw-scaled Viper (genus Echis), which kills 1,000’s of people every year.
  • Which snake’s venom kills people the quickest? This is likely a species of Cobra (genus Naja), many of which possess fast-acting neurotoxins in their venom that can paralyze the diaphragm and cause death by asphyxiation within 30 minutes.
  • Is there a snake whose bite means certain death without antivenom or hospital care? Yes, the Black Mamba (Dendroaspis polylepis) has a 100% mortality rate in humans without supportive medical care (either to administer antivenom or to breathe for you when the potent neurotoxins take effect and cause your diaphragm to stop working).
  • Which snake has the most toxic venom? Drop for drop, the Inland Taipan (or Fierce Snake, Oxyuranus microlepidotus) has the world’s most toxic venom towards mice, with an LD50 of 0.01 mg of venom per kg of mouse body weight [reported in the form of 0.01 mg/kg (milligram per kilogram) or 0.01 ug/g (microgram per gram); ref #1]. Interestingly, there are no confirmed human casualties from this species. People often claim that certain species of sea snakes are the most toxic snakes, but the Belcher's Sea Snake (Hydrophis belcheri) "only" has an LD50 of 0.24 mg/kg (ref #3; similar to the Black Mamba, Dendroaspis polylepis, with an LD50 of 0.264 mg/kg; ref #2), the Beaked Sea Snake (Enhydrina schistosa) has an LD50 of 0.164 mg/kg (ref #1), and the Olive Sea Snake (Aipysurus laevis) has an LD50 of 0.12 mg/kg (ref #3).
  • Which snake has the most venom? The Gaboon Viper (Bitis gabonica) is capable of producing the highest venom yield, with up to 9.7 ml of venom (equal to 2.4 kg or 5.3 lbs of dried venom) from a single snake.

Longest Snake in the World

The Reticulated Python (Python reticulatus) grows to be the longest snake in the world, at 33' long.  This individual is only 17' long, 120 lbs, and resides at the Fort Wayne Children's Zoo.
The Reticulated Python (Python reticulatus) grows to be the longest snake in the world, at 33' long. This individual is only 17' long, 120 lbs, and resides at the Fort Wayne Children's Zoo.

What are some snake records?

  • What is the largest snake in the world? This is a complicated question, so we will break it down into two, more specific, questions.
  • What is the longest snake in the world? Among extant (opposite of extinct, meaning still living today) snakes, the Reticulated Python (Python reticulatus) grows to be the longest snake. From Southeast Asia, it is a terrestrial/semi-arboreal predator known to reach 33' long and 440 lbs. The longest one maintained in captivity was an 8 year old snake named Medusa that was just over 25' long and 350 lbs.
  • What is the heaviest snake in the world? Among extant snakes, the Green Anaconda (Eunectes murinus) grows to be the heaviest snake. From South America, it is an aquatic ambush predator known to reach 28' long and 550 lbs.
  • Which venomous snake is the longest? The King Cobra (Ophiophagus hannah) reaches just over 18’ in length.
  • Which venomous snake is the heaviest? The Gaboon Viper (Bitis gabonica) can get up to 44 lbs.
  • Which venomous snake has the longest fangs? The Gaboon Viper (Bitis gabonica) can grow fangs up to 2.2” long.
  • What is the biggest snake to have ever lived? The Titanoboa (Titanoboa cerrejonensis) lived ~60 million years ago and grew to be ~45’ long and ~2,500 lbs.
  • Which snake is the fastest? The Black Mamba (Dendroaspis polylepis) is often touted as being the world’s fastest snake, capable of moving at speeds up to 9 mph (only about 1/3 of the record running speed for humans).
  • Which snake lives the longest? The Rubber Boa (Charina bottae) is known to reach ~60 years old.

Threat of Human Strangulation by Large Constrictors

This Red-tail Boa Constrictor (Boa constrictor constrictor) is at the size (~8' long) where it can overpower an adult human and strangle them to death. Only handle powerful snakes this large with someone else nearby to help. Pic of Megan K. Caylor.
This Red-tail Boa Constrictor (Boa constrictor constrictor) is at the size (~8' long) where it can overpower an adult human and strangle them to death. Only handle powerful snakes this large with someone else nearby to help. Pic of Megan K. Caylor.

Rattlesnake Defensive Posture

A Western Diamondback Rattlesnake (Crotalus atrox) assuming a classic strike posture upon being backed into a corner.  Such defensive behavior is commonly mistaken as being snake aggression.
A Western Diamondback Rattlesnake (Crotalus atrox) assuming a classic strike posture upon being backed into a corner. Such defensive behavior is commonly mistaken as being snake aggression.

Snake Lying Down Next to Child

A 5' long, 7 lb Ball Python (Python regius) laying down next to a 3.5' tall, 42 lb, 5.5 year-old, sleeping child to get warm. Snakes don't "size up" prey by lying next to them, whether in captivity or in the wild. Pic of Jadyn M. Smith.
A 5' long, 7 lb Ball Python (Python regius) laying down next to a 3.5' tall, 42 lb, 5.5 year-old, sleeping child to get warm. Snakes don't "size up" prey by lying next to them, whether in captivity or in the wild. Pic of Jadyn M. Smith.

Adult vs Baby Prairie Rattlesnake

An adult Prairie Rattlesnake (Crotalus viridis viridis) lying its head down next to a baby.  Adult venomous snakes generally pose more than 5x the threat to human well-being than neonates do.
An adult Prairie Rattlesnake (Crotalus viridis viridis) lying its head down next to a baby. Adult venomous snakes generally pose more than 5x the threat to human well-being than neonates do.

What are some myths and misconceptions about snakes?

  • I’ve seen/heard some terrifying things about snakes, so how can I tell what is true? Snakes are common victims of misinformation and fear, so please don’t always believe what you hear. The key is to critically analyze the information using logic and reason, as well as researching the topic at hand (using credible sources and expert testimony).
  • Do snakes eat people? On the extremely rare occasion, when a very large snake has the opportunity to do so, it may decide to kill and swallow a human. Some snake species (notably large constrictors, like boas and pythons) are capable of ingesting something that weighs as much as they do. To give you an idea of how big a snake has to be in order to consume a human, a healthy 17’ long Reticulated Python (Python reticulatus) weighs 120 lbs, meaning that it could eat a 120 lb person. This also requires the snake to recognize people as food (as many snakes will ignore things that don’t look/smell like "normal" prey unless they are starving). So, you shouldn't worry about that 7' long pet Boa Constrictor trying to eat you, because it can't.
  • Can a constrictor strangle a person to death? If the snake is large enough to consider humans as prey, then the obvious answer is yes. Otherwise, a good rule to follow is if a snake is over ~8’ long, then it is capable of overpowering an adult human and strangling them to death. This requires the snake to be adequately motivated to do so, either by being scared for its life and acting out of defense, or by intending to consume that individual (if it is large enough).
  • How can I remove a large constricting snake once they've wrapped around me or others? Snakes normally begin constricting an animal by throwing body coils around them, starting from the snake’s head. This means that in order to remove a snake that has already coiled around something, you must begin unwrapping the snake from the tail. Whenever handling large constrictors over 8’ long, it is a good idea to have other people around to help, just in case. Another method that might be utilized with some degree of effectiveness to remove a large constrictor that has already coiled is to keep a bottle of liquor (preferably 70 proof or higher) readily available to pour onto/into the snake’s mouth (as ethanol is considered a toxin by most animals, including snakes) until it releases its hold and flees.
  • If a large constricting snake lies down next to a person, is it "sizing them up" to eat them? No. For example, take a 5' long Ball Python (Python regius) that lies down next to a 5.5 year-old child that's only 3.5' tall. Although one might suspect that the python could easily consume the child due to the 1.5' difference in length, you must also keep in mind that the child is ~12" wide, not ~3" wide, and at least twice at deep as the snake. These factors result in the child weighing 42 lbs, with the snake only weighing 7 lbs. The child is approximately six times larger than anything this snake could possibly consume. So, this myth has no scientific basis, as large constricting snakes often have to be over three times longer than a person is tall in order to try to consume them. If a snake is lying on or next to a person, it is likely due to the snake wanting to draw in warmth from that person's body, not the snake trying to kill or eat the person. Snakes never lie down next to prey to "size them up" before consuming them.
  • What about reports that snakes up to 40’ long have been found? Snake size is often over-estimated by a factor of 2. In an effort to misrepresent snake size, pictures are sometimes taken with the snake much closer to the camera than the people in the background, giving the illusion of a snake that is very large. Additionally, snake skins are unreliable, as they can be stretched to a substantial degree. This is why reliable record snake sizes are only recorded in living animals or those that have recently died by qualified personnel.
  • Why are snakes so aggressive? Snake “aggression” is normally mistaken for curious, defensive, territorial, or maternal behavior. Please bear in mind that humans are much bigger than most snakes, meaning that you are often perceived as a potential predator that the snake will have to defend itself from.
  • Can I contract rabies from snakebite? Can I get salmonella from handling snakes? Only a select few diseases may be contracted from snakes, notably tetanus, salmonella, and influenza A/B. Although such events are very rare, you can effectively protect yourself by keeping up on your tetanus immunizations (at least one every ten years) and washing your hands after handling snakes.
  • How can I get snakes to like me and how should I handle a snake? Snakes tend to react “well” to things they perceive as “substrate/nonliving” or harmless. So, by moving fairly slowly/carefully/gently (preferably from underneath the snake’s head, as most things coming from above are either predators or prey) and by not looking/acting/smelling like a predator or prey, you can often get a snake “accustomed” to being handled by you.
  • Aren’t baby venomous snakes more dangerous than adults because their venom is more toxic and they haven’t learned to control their venom output? No. Although young snakes tend to possess lower LD50 values (in mice; with up to ~twice the adult snake’s toxicity per drop of venom), adult snakes can inject over ten times the amount of venom of a neonate snake, meaning that adults are commonly greater than five times more dangerous than young snakes. Add to this the fact that snakes are fully capable of regulating their venom output from birth, adults really do pose a much larger threat to people than younger snakes.
  • Is snake venom evolving to be more deadly towards humans? No. Snakes rarely hybridize with other species, and those events don’t result in the creation of snake species/subspecies with “super-deadly” venoms. Even though many snake species are involved in an “arms race” against the innate venom resistance mechanisms of their prey and all snake venoms are subject to an accelerated rate of evolution, these processes tend to operate over a large timescale (1,000’s of years) and don’t necessary result in venoms that are more potent towards humans.
  • What should I do if I am bitten by a venomous snake? If you are envenomated by a front-fanged snake, the best thing you can do is keep calm, restrict your movement, and make your way to a hospital. "Snakebite Extraction Kits" utilize a "cut-and-suck" method (popularized in movies) that does a lot more harm than good. Snake venom has evolved to disperse immediately from the bite site in order to quickly and efficiently disable prey. This means that "cutting" the fang marks and trying to "suck" out the venom will result in minimal venom removal and a high amount of unnecessary tissue damage. Do NOT ever purchase/use Snakebite Extraction Kits or the "cut-and-suck" method! Since most rear-fanged snakes are harmless, basic first aid techniques will adequately clean and treat wounds from rear-fanged or nonvenomous snakes.

Snakes Kill Many Common Pests

In addition to rodents, snakes consume a wide variety of species that humans often consider as pests, such as Grasshoppers, Slugs, Spiders, and Centipedes.  This behavior works for, not against, human economies.
In addition to rodents, snakes consume a wide variety of species that humans often consider as pests, such as Grasshoppers, Slugs, Spiders, and Centipedes. This behavior works for, not against, human economies.

Snake - Human Conflict

Invasive species, such as this Brown Treesnake (Boiga irregularis), often conflict with human interests, pitting man against snake.  Pic is of the article author (Christopher J. Rex).
Invasive species, such as this Brown Treesnake (Boiga irregularis), often conflict with human interests, pitting man against snake. Pic is of the article author (Christopher J. Rex).

Why are snakes worth keeping around?

  • Do snakes serve any real purpose? Snakes, like virtually all other creatures in the natural world, play a specific role in the environment. Most of the time, these roles work in tandem with human interests (not against them).
  • Are snakes good for the economy? Snakes often feed upon creatures that humans consider as common pests, such as grasshoppers, slugs, spiders, centipedes, ants, termites, rodents, squirrels, rabbits, lizards, and sparrows (including their eggs). This natural form of pest control saves billions of dollars every year (in agricultural crop yields, human suffering, etc.).
  • Are there any snakes that cause more problems than they solve? There are some species of snakes that have been introduced (often accidentally) into regions of the world where they are not native. Such snakes are considered to be "invasive species" in those regions, as they often wreak havoc on those ecosystems due to them being removed from natural predators and disease. In the U.S., Burmese Pythons (Python morulus bivittatus) were accidentally unleashed in Florida after Hurricane Andrew in 1992. They have since become well-established and have been known to get up to 17.5' long and weigh 165 lbs (large enough to consume humans). Brown Treesnakes (Boiga irregularis) were accidentally transported on ships to Guam in the late 1940s and have since wiped out a significant portion of native life on the island, due to their population reaching approximately 2 million.
  • Are snakes needed to make antivenom? Venom from venomous snakes is injected into sheep in order to make CroFab antivenom in the United States (other antivenom companies may inject snake venom into animals like horses or goats, instead). The sheep produce antibodies to the venom, which are collected and then purified for injection into humans. Nonvenomous snakes (king/rat snakes) that consume venomous snakes frequently possess an innate resistance/immunity to snake venom that could help us develop more effective antivenoms.
  • Can drugs be made from snake venom? Absolutely! There are over ten different pharmaceuticals currently being used in the U.S. that were derived from compounds in snake venom and designed to aid human suffering.

Example of Saltation in Snakes

Disclaimer

This hub is intended to educate people ranging from snake experts to laymen about many questions they might have regarding snakes. This information contains generalizations and by no means encompasses all exceptions to the most common "rules" presented here. This information comes from my personal experience/knowledge as well as various primary (journal articles) and secondary (books) literature sources (and can be made available upon request). All pictures and videos, unless specifically noted otherwise, are my property and may not be used in any form, to any degree, without my express permission (please send email inquiries to christopher.j.rex@gmail.com).

I wholly believe feedback can be a useful tool for helping make the world a better place, so I welcome any (positive or negative) that you might feel compelled to offer. But, before actually leaving feedback, please consider the following two points: 1. Please mention in your positive comments what you thought was done well, and mention in your negative comments how the article can be altered to better suit your needs/expectations; 2. If you believe that any of the information contained in this article is lacking sufficient detail or is incorrect, then please leave a detailed comment addressing the issue and citing your sources (web links, books, journal articles, etc.).

If you enjoyed this article and would like to find out how you can help support snake venom research examining the pharmaceutical potential of various snake venom compounds, please check out my profile. Thank you for reading!

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References

I am currently attempting to go through and fully source all of the points I have presented in this article. As there is an awful lot of information here, it is a daunting task that will require much time and effort that I don't necessarily have (so, please be patient). In addition, although I generally make attempts to provide links to free articles, it is not always possible to do so. If you desire a full-text pdf of any of these articles, please feel free to email me to request a copy.

  1. Broad, A.J., Sutherland, S.K., Coulter, A.R., 1979. Lethality in mice of dangerous australian and other snake venom. Toxicon 17, 661-664.
  2. Irwin, R.L., Oliver, K.L., Mohamed, A.H., Haast, W.E., 1970. Toxicity of Elapidae venoms and an observation in relation to geographical location. Toxicon 8, 51-54.
  3. Tamiya, N., Puffer, H., 1974. Lethality of sea snake venoms. Toxicon 12, 85-87.

© 2013 ChristopherJRex

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    • profile image

      Vikas 2 years ago

      I'm not going to argue the species, not havnig seen the critter. To find a cotton-mouth under a shed would surprise me, since I've never seen one very far away from the pool he lives in. All of the water moccasins' I've seen around here are simply water snakes.In addition to the black color, and the cotton-white in-side-the-mouth coloration, they boast very thick bodies. A two foot long snake might be almost four to six inches in diameter. Chubby rascals. And they're ill-tempered and aggressive, not accepting their lowly status on the food chain.If the concern is over poisonous snakes vs. snakes, I'd seek out a King Snake, since they prey on poisonous snakes and are a pleasure to have around the yard.

    • profile image

      Sagi 2 years ago

      BION I'm impeessrd! Cool post!

    • profile image

      brian 3 years ago

      Will a poison snake move in a straight line

    • profile image

      German Echeverry (Colombia, S.A.) 3 years ago

      Great!

    • ChristopherJRex profile image
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      ChristopherJRex 4 years ago from Fort Wayne, IN

      Melissa A Smith: I'm happy that you found the article useful! My intent is to help "bridge the gap" in the snake knowledge of the general public while still being able to assist those that desire more "advanced" information (researchers, professionals, educators, etc.).

      samowhamo: Even though it depends on where you go and what exactly you want to do in Herpetology, you are generally required to have good math skills (typically through the Calculus level) in order to adequately prepare you for performing Statistics on your data. If you truly love Herpetology and are willing to work hard at it, you can surely make it work, though! Good luck!

    • samowhamo profile image

      samowhamo 4 years ago

      Good article I myself write about herpetology and paleontology. May I ask you I have read that herpetology requires mathematics I am not very good at math is that going to be a problem for me because I want to pursue a career in herpetology.

    • Melissa A Smith profile image

      Melissa A Smith 4 years ago from New York

      What a great resource Christopher. Comprehensive and true. So many people are ignorant to basic snake facts.

    • ChristopherJRex profile image
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      ChristopherJRex 4 years ago from Fort Wayne, IN

      Tsadjatko: Thanks for the fun joke! :)

      Rob: I’m glad that you really liked the article!

      Insane Mundane: Unfortunately, snakes only have a very limited ability to hear airborne sounds (as stated above). This means that your “stereotypical” snake charmer (that “charms” a snake with his flute) is doing little more than entrancing the snake with his movements, not his music (which is why you normally witness the charmer wavering back and forth, with the snake following suit). Snakes may appear to be apathetic due to the fact that Reptiles have a “simpler,” streamlined brain morphology/physiology that makes them focus on critical life functions, such as eating, reproducing, and survival (including things such as thermoregulation and self-defense). Snakes aren’t bogged down by complicated thoughts and “feelings.” Thanks for commenting, as I’ll be sure to incorporate those bits of information into the hub!

    • Insane Mundane profile image

      Insane Mundane 4 years ago from Earth

      As for my prior question, spare me the cold-blooded traits as that would only end in a senseless ramble, just as y'all used to think that all the dinosaurs were cold-blooded creatures; ha!

    • Insane Mundane profile image

      Insane Mundane 4 years ago from Earth

      Why do snakes seem to always be a creature of apathy unless music is played or sounds are heard? ...Not counting the slithering when you touch 'em, of course, as they couldn't care less... Hey, this is the FAQ section, right? LOL!

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      rob 4 years ago

      very cool article, I really enjoyed it.

    • tsadjatko profile image

      TSAD 4 years ago from maybe (the guy or girl) next door

      Why didn't the snakes leave Noah's Ark and multiply like all the other animals?

      They couldn't multiply. They were adders!

      You're welcome!

    • ChristopherJRex profile image
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      ChristopherJRex 4 years ago from Fort Wayne, IN

      Thanks Minnetonka Twin and tsadjatko! I'm really glad that you two enjoyed the article!

    • Minnetonka Twin profile image

      Linda Rogers 4 years ago from Minnesota

      Wow, this is an extensive article on snakes. I will come back and re-read it some parts. Great job and great photo's that make this an interesting and fascinating read.

    • tsadjatko profile image

      TSAD 4 years ago from maybe (the guy or girl) next door

      This is just an AWESOME hub page! Unbelievably informative and presented in the greatest way possible!!