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Lobster Facts, Photos, and Biology: Interesting Invertebrates

Linda Crampton is a writer and experienced science teacher with an honors degree in biology. She enjoys writing about science and nature.

An attractive European lobster, or Homarus gammarus

An attractive European lobster, or Homarus gammarus

Interesting Animals

To many people, a lobster is simply a source of tasty meat that's fun to eat at social events. Living lobsters can be fascinating animals to observe and study, however. They deal with the problems of living very differently from humans. They have gills instead of lungs, different sense organs, and a nervous system that has ganglia—nerve centers—but not a true brain. Nevertheless, they are very successful creatures and are found in all oceans of the world.

My interest in the animals began when I was at a high school event shortly after I arrived in Canada from the UK. A container of live lobsters was present to feed the crowd. Another student told me that the animals were going to be put into boiling water to cook, something that I had never heard of before. I was horrified and refused to eat any lobster meat. Boiling the animals alive seemed incredibly cruel to me. I did eat other types of meat, however. It didn’t occur to me that this too could be seen as a form of cruelty to animals, depending on how the animals are treated.

Lobster Classification

Class Animalia

Phylum Arthropoda

Class Crustacea

Order Decapoda

Family Nephropidae

Genus (of the American lobster) Homarus

Species (of the American lobster) americanus

The Body of a Lobster

Lobsters are crustaceans (members of the class Crustacea) and belong to an order of animals called the Decapoda. Their body is divided into two sections. The first is known as the cephalothorax. This contains the head and the thorax and is made of fused segments. The eyes, antennae, and mouth parts are attached to the head, or cephalon, and the legs are attached to the thorax.

The second body section is the abdomen, which consists of a visibly segmented region and a wider tail at the end. The underside of the abdomen has multiple pairs of swimmerets (or pleopods) attached to it, which help the lobster to move.

Claws, Legs, and Locomotion

The order name "Decapoda" refers to the ten legs of an animal in the order. Crabs, crayfish, shrimp, prawns, lobsters, and some other animals belong to the order. Their legs are arranged in five pairs.

The first pair of legs of many lobsters are greatly enlarged to form claws. One claw is larger than the other one and is known as the crusher claw. The smaller one is called the pincer claw. The claws are used for manipulating objects but not for walking. Interestingly, some lobsters have the crusher claw on their right side while others have it on the left side, so the animals have a form of handedness. The remaining four pairs of legs are the walking legs.

Lobsters usually move by walking along the ocean floor. When they're threatened, they may swim backwards rapidly by curling the underside of the abdomen and tail up toward the cephalothorax and then uncurling it again. Some reports claim that the animals can move at up to five meters a second using this procedure. It’s known as a caridoid escape reaction. The adjective “caridoid” comes from the name of the infraorder Caridea, which contains the true shrimp. These animals exhibit the same escape reaction as lobsters.

Spiny lobsters belong to the family Palinuridae in the order Decopoda. They look quite similar to the animals in the genus Homarus but have some important differences.

The Exoskeleton and Molting

The lobster's skeleton is on the surface of its body instead of on the inside and is known as an exoskeleton or a shell. As the animal grows, it periodically sheds its exoskeleton in a process called molting. This is necessary because the exoskeleton is too hard to allow the lobster's body to expand.

The animal that emerges from the old shell is in a very delicate state. It's covered by a new exoskeleton that formed under the old one. The new covering is soft and needs time to harden. The softness of the new shell allows the lobster's body to increase in size but also makes the animal vulnerable to predators. In the wild, molting generally happens in a secluded place, such as a burrow.

Not all animals with "lobster" in their name are true łobsters. True łobsters belong to the family Nephropidae within the order Decapoda. Spiny lobsters, squat łobsters, and slipper lobsters don't belong to this family. The molting process of the spiny lobster that's shown in the video above is quite similar to that of a true lobster, however.

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American Lobster Facts

The American lobster (Homarus americanus) lives on the east coast of North America in Canada and the United States. In the descriptions given below, the word "lobster" refers to this animal. European lobsters (Homarus gammarus) are close relatives of the American species.

Most American lobster shells are olive green or red brown in color. The shell may have orange highlights and may sometimes have blue markings around the joints. Very rarely, the animal is completely blue. Red lobsters are even rarer. Yellow lobsters are extremely rare. Albino lobsters—those with no pigment—also exist. The video below shows blue, yellow, and white animals. The next one shows a calico lobster.

According to the Lobster Institute at the University of Maine, an estimated one in two million American łobsters is blue, one in ten million is red, and one in thirty million is yellow. The frequency of calico (orange and brown) lobsters is also one in thirty million.

Sight and Detecting Vibrations

Viewing the Environment

The eyes of lobsters are located at the ends of short stalks and are movable. The animals have compound eyes that give them a 180 degree view of the world. It’s thought that the eyes are sensitive to light intensity and movement but don’t produce a very clear image.

The eyes are interesting because they contain mirrors instead of lenses. Each of our eyes—and the eyes of most other animals—contains a lens that refracts (bends) light rays so that they hit the retina, the light-sensitive layer at the back of the eyeball. The lobster eye is made of many tube-like segments, each containing reflective surfaces that act as mirrors instead of a lens. The mirrors reflect the light rays onto the retina.

Sensing Vibrations

Sound is created by vibrations at the specific frequencies that an ear can detect. When the ear is stimulated, it sends a signal to the brain. This creates the sensation of sound. Lobsters almost certainly can't sense sounds in the way that we do, since they don't have any sense organ that behaves like our ears. They do detect vibrations, though. They also produce low frequency vibrations themselves by contracting and relaxing special muscles at the base of their antennae. This causes the carapace (the exoskeleton over the cephalothorax) to vibrate. The function of the vibrations is uncertain, but they may play a role in defense.

Sense of Smell, Taste, and Touch

Lobsters have an excellent sense of smell. They use the first, shorter pair of antennae to detect scents. These short antennae, which each consist of two branches, are actually known as antennules. The many tiny hairs on the antennules pick up a wide range of odors.

The mouth parts and the legs of a lobster have taste receptors. The second, longer pair of antennae are sensitive to touch. The exoskeleton has fine hairs that also sense touch.

In 2016, a 23-pound lobster was caught in the province of New Brunswick in Canada. It was estimated to be a hundred years old. Lobsters can live for a long time, though a hundred years seems to be around the upper limit. There are claims that far heavier lobsters have been caught, including a 44-pound, three-and-a-half-foot long animal that is said to have been found off the coast of Eastern Canada in 1977.

Gills of a Lobster

Above the walking legs on each side of a lobster’s body is a space under the exoskeleton called the branchial chamber (or sometimes the gill chamber). The lobster’s gills are located in these chambers. If the shell on the side of a lobster is removed, the gills can be seen. The branchial chamber is lined with a thin layer of shell on its inner wall.

The internal anatomy of a crayfish is very similar to that of a lobster. In the crayfish anatomy video below, the gills are shown, although the narrator never refers to them. The gills are the segmented clumps of tissue on each side of the crayfish above the walking legs. They look like clumps because they are dried out and stuck together. When the gills are placed in water they separate, revealing a feathery structure.

There are twenty gills in each branchial chamber of a lobster. Each gill consists of a central rod with projections extending all around it. Most of the projections are long and look like filaments. The gill is often said to resemble a bottlebrush. The base of each gill is attached to the wall of the branchial chamber or to the legs. Therefore, when a leg is removed from a lobster a gill may be removed as well.

Respiration Facts

Sea water reaches the gills through the opening at the bottom of the branchial chamber. As the water moves upwards and forward over the gills, the gills extract oxygen from the water. The oxygen is then transported by the blood to the lobster's cells. The blood picks up carbon dioxide waste from the cells and transports it to the gills, where the carbon dioxide is released into the water that is flowing over the gills. The water in a branchial chamber moves out through an opening at the front of the chamber.

The current that moves the water over the gills is created by a structure called the gill bailer, or scaphognathite. This is a flap attached to a mouth part and is almost constantly beating. Sometimes the gill bailer changes the direction of its beat for a short time in order to reverse the direction of water flow and sweep sea water over the gills, removing any debris that has become trapped on them.

Lobsters may be able to live out of water for one or two days if they stay cool and their gills stay moist.

Overview of the Digestive System

Esophagus and Two Stomachs

Lobsters aren't scavengers, as was once thought. They prefer to catch live prey, such as fish, crabs, clams, snails, and starfish. The mouth parts of the lobster begin the breakup of the prey. The small pieces of food then pass into the esophagus.

The esophagus sends the food into the first stomach, which is called the cardiac stomach. The structure contains teeth-like structures that form the gastric mill. The mill breaks the food up into smaller pieces. The second stomach is known as the pyloric stomach. It contains structures that filter the food particles according to size. It also contains digestive enzymes that break the particles into smaller ones.

Digestion Completion and Absorption

The smallest particles in the pyloric stomach pass into the digestive gland, where they are further digested by the enzymes produced there. The tiny particles that are created then travel into the bloodstream through the lining of gland. The remaining food in the pyloric stomach travels into the intestine as the digestion process continues. The particles that are produced are absorbed through the intestinal lining. Indigestible material is excreted as fecal pellets through the anus.

The Digestive Gland or Tomalley

Some of the processes that occur in the digestive tract of a lobster aren’t fully understood yet. The digestive gland of the animal is sometimes called a hepatopancreas and is often said to play a role somewhat similar to that of our liver and pancreas. Some researchers don’t believe that this is an accurate description of the structure’s function, however.

The digestive gland is also known as tomalley when someone is treating a lobster as a food source. Tomalley is a soft and green material that some people consider to be very tasty. It may collect toxins, however, which is something to be aware of if a person wants to eat it.

Circulatory and Excretory Systems


Lobsters have an "open" circulatory system. Their heart pumps blood (technically called hemolymph) into arteries, but the arteries lead to blood cavities called sinuses instead of to other blood vessels. The blood travels through sinuses and channels back to the heart. The animals have colorless blood, which turns slightly blue when exposed to oxygen. Their respiratory pigment is called hemocyanin.


Like our cells, those of a lobster produce waste substances that must be removed from the body. The excretory glands are called the green glands and are located at the base of the antennae. The glands release the waste substances into the surrounding water. They shouldn't be confused with the green digestive gland, or tomalley, which is located beside the digestive tract.

Lobsters can regenerate their claws, their walking legs, and their antennae. They may drop a claw spontaneously, which is useful if they want to escape from a predator.

Nervous System

A lobster's nervous system is based on ganglia and nerves. These are made from neurons, or nerve cells. A neuron consists of a cell body, which contains most of the cell's organelles, and a fiber called an axon extending from the cell body. A ganglion is a group of cell bodies from several neurons. A nerve is a group of axons bundled together.

A lobster has a large pair of ganglia in its head near its eyes, which is sometimes referred to as a brain. The structure doesn't have the complex structure of a vertebrate brain, though its abilities shouldn't be underestimated. A double nerve cord extends from the "brain" to the lower part of the lobster’s body and then travels towards the rear of the animal. The nerve cord has a pair of ganglia in almost every segment of the lobster and gives off nerves that go to the various parts of the body.

This is a vertebrate neuron, showing the cell body and the axon extending from it. Lobsters are invertebrates, but they have neurons, too.

This is a vertebrate neuron, showing the cell body and the axon extending from it. Lobsters are invertebrates, but they have neurons, too.

Neurons in animals have the same basic structure. They may not look identical in all animals or in every part of an animal, however.

Do Lobsters Feel Pain?

Do lobsters and their relatives feel pain? Researchers can't answer for certain. There are scientists on both sides of the debate. Some claim that lobsters and other invertebrates do feel pain and stress; others say that it's unlikely that they feel pain due to their relatively simple nervous system.

To me it seems unlikely that lobsters and other invertebrates have evolved without being able to perceive some kind of pain sensation. Feeling pain is a protective mechanism to prevent damage to an organism's body. The brain of lobsters doesn't have a cerebral cortex, the part of our brain that perceives pain. This doesn't rule out the possibility that the animals are perceiving pain by a different mechanism than we use. In any case, since no scientist can guarantee that lobsters are unable to feel pain, the onus should be on us to kill them humanely if we want to eat them.

The eggs of a female American lobster

The eggs of a female American lobster

Reproduction of the American Lobster

In the American lobster, the female releases a pheromone to attract a male. The male's first pair of swimmerets are rigid and grooved. They are used to insert sperm into the female's sperm receptacle.

The female retains her unfertilized eggs in her body for many months. Eventually she releases her eggs, which are fertilized by the sperm from her receptacle and then stick to her swimmerets. Here they stay until they hatch.

The youngsters that leave the swimmerets are tiny larvae. They molt as they grow and go through several developmental stages. Eventually (if they survive predation), they develop a typical lobster form.

There are probably many more facts about the lives of lobsters to be discovered. They are interesting animals and have some impressive characteristics. It's a shame that many people think of them only as food.


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2012 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on April 05, 2014:

It does indeed, Perspycacious! It's a shame that there is no way to control which ads appear.

Demas W Jasper from Today's America and The World Beyond on April 05, 2014:

Somehow doesn't it seem ironic that your article is used as a billboard for advertising "tasty" lobsters for sale?

Linda Crampton (author) from British Columbia, Canada on April 04, 2014:

Hi, Mary. Thank you for the comment. The fact that people often assume that so-called "lower" animals can't feel pain and therefore treat them badly is worrying.

Mary Finelli on April 04, 2014:

Thank you for your interest and concern for these admirable animals. Since there is scientific evidence that lobsters are aware and can feel pain, we have a moral obligation to not cause them needless harm. There are many marvelous vegan alternatives to eating lobster. Recipes, products and more can be found at www.Fish

Linda Crampton (author) from British Columbia, Canada on March 10, 2012:

What a huge price difference, cabmgmnt! Yes, it would have been very strange to buy expensive Maine lobsters in Paris instead of inexpensive ones in New England! Thanks for the visit and the interesting comment.

Corey from Northfield, MA on March 10, 2012:

Great hub. I was in Paris in the late eighties and ate at a very exclusive restaurant. They had a tank of live Maine lobsters and they were at market price. Back then in 1989 the market price in that Parisian restaurant was $87 US dollars per pound!!!! Needless to say, I didn't have Maine lobster in Paris. I waited until I was back home in New England ang could get them for $2.99 a pound...remember this was the eighties! Thanks for this informative hub.

Linda Crampton (author) from British Columbia, Canada on March 10, 2012:

Hi, Susan. Thanks for the visit and the comment. It can very upsetting to see live lobsters put into boiling water, especially for children. I wasn't happy when I first heard that it happened, and certainly couldn't watch it take place!

Susan Zutautas from Ontario, Canada on March 10, 2012:

I remember the first time I saw my parents put live lobsters into boiling water I cried. As soon as I heard what seemed like the lobsters screaming I felt like my parents were the cruelest people ever. I refused to eat lobster until I was 20 years old.

I never knew much about lobsters and found you hub so fascinating and very educational.

Linda Crampton (author) from British Columbia, Canada on March 09, 2012:

Thanks for the visit, the rating and the share, Nell. Yes, lobsters certainly do have a strange stomach, and they have some other unusual characteristics too!

Nell Rose from England on March 09, 2012:

Hi, I have never liked the idea of putting them in boiling water, I agree with you, even though they don't have a brain similar to ours, they must feel pain. fascinating information, I didn't realise they had two stomachs and teeth within the first one, rated up and shared! nell

Linda Crampton (author) from British Columbia, Canada on March 09, 2012:

Hi, drbj. Thank you very much for your kind comment. Lobsters can be very surprising animals! There's so much that researchers still need to learn about them. I expect that we'll discover some more interesting facts about them in the near future.

Linda Crampton (author) from British Columbia, Canada on March 09, 2012:

Thank you very much for the comment and the vote, Emma. Yes, what one source describes as a humane method of killing lobsters another describes as cruel. It's a very difficult situation for people who like lobster meat but want to treat lobsters as well as possible at the same time.

drbj and sherry from south Florida on March 09, 2012:

I enjoy the taste of lobster, Alicia, but I cannot boil them myself. I take the coward's way out and leave that to restaurants. This was an eminently readable hub, m'dear, and I enjoyed every nugget of information you so carefully researched and published. Thank you. So lobsters have teeth? In their stomachs? Who knew?

Emma Kisby from Berkshire, UK on March 09, 2012:

Wow AliciaC, what an amazing hub and so well written.

Lobsters are creatures I really knew little about. It is fascinating to learn so much about them.

As for eating them, I have heard of ways to kill them humanely which contradict one another - any way to kill is cruel.

Voting up - very interesting indeed.

Linda Crampton (author) from British Columbia, Canada on March 08, 2012:

Hi, Lesley. Thanks for the visit and the comment. I think that lobsters and their lives are interesting too! There are many different species to study, so I expect we'll discover more fascinating facts about them in the future.

Movie Master from United Kingdom on March 08, 2012:

Hi Alicia, I knew nothing about lobsters, except they taste good - I was missing out they are really interesting!

I had no idea they lived to such an age or can grow so big.

An excellent article, thank you and voted up.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Hi, teaches12345. I have never eaten lobster, and I certainly couldn't cook a live one myself! I'd much rather study them as an animal in nature than as a food source, even though people say that their meat is delicious. Thanks for the vote.

Dianna Mendez on March 07, 2012:

Blue and yellow lobsters are news to me! I am not a fan of this meal option but my hubby loves it. We bought a huge cooking pot to cook them once but have not used it since. Like you, I didn't know that you had to cook them live and couldn't eat it afterwards. Great informational hub on lobster facts (two stomachs?). Voted up.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Hi, b. Malin. Thank you for the comment. Yes, some lobsters do have the ability to live for a long time. They are very interesting animals, and there's so much still to be learned about them!

b. Malin on March 07, 2012:

So a Lobster can live to be l00...if all goes well for it...and it's not caught! What an Interesting Subject you have chosen to tell us about Alicia. I can't imagine that the Lobster doesn't feel pain, I would being dumped into a pot of Boiling Water! Thanks for another Educational Read.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Thanks for the very interesting information, Perspycacious. It's sad to realize how abundant the lobsters were in the past compared to their population size today.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Thank you very much for both the lovely comment and the vote, Tina! I completely agree with your opinion about animals and the ability to feel pain, even though we don't know for certain what another animal is experiencing.

Demas W Jasper from Today's America and The World Beyond on March 07, 2012:

Today's price for live Maine lobsters (hard shelled)with two claws and 1.25 lbs.size is $7.49/lb. When the Pilgrims were in Plymouth, Massachusetts the lobsters were so plentiful that the Pilgrims could go to the shore and pick them up to use as fertilizer in their garden plots!

Christina Lornemark from Sweden on March 07, 2012:

Lobsters are interesting and fascinating animals and this hub is packed with information about them. They must be very good at adapting to their environment since they have been here for more than 300 million years! There is still so much we don't know about animals but personally, I think most animals can feel pain, at least in some way, even if it is in a different way compared to how we feel pain.

You have done a fantastic hub about Lobsters, very good information and great videos too! Thanks, voted up!


Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Thank you very much for the comment, and thanks for the information about the white clawed crayfish, JKenny. I wasn't aware of the problem with this animal's population. People are sometimes concerned when cute, furry animals are in trouble, but aren't so worried when invertebrates are endangered, which I think is a great shame. I hope the crayfish survives.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Thanks, Tom. As always, I appreciate your visit and kind comment. Thank you for the vote too!

James Kenny from Birmingham, England on March 07, 2012:

What a great hub, so rich in detail. I can tell you've put a lot of time and effort into this hub. I remember going Crab and Lobster fishing when I was kid, it was fun, but we always threw them back. Funny you mentioning crayfish. We have a freshwater crayfish in England called the White Clawed Crayfish, but at the moment, it's in serious decline on account of the invasive American Signal Crayfish, shame, hope it doesn't go extinct.

Thomas Silvia from Massachusetts on March 07, 2012:

Hi my friend, great hub,thanks for this different look at lobsters as more than a delicious meal. It was very interesting and fascinating to learn more about these sea creatures .

Vote up and more !!!

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Thank you for the comment and the vote, John. I appreciate your visit!

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Hi, CMHypno. I hate the way that people just assume that animals like lobsters can't feel pain. They do have sense organs and a nervous system, even if they're simpler than ours, and the function of these structures is to transmit messages about the environment. We really don't know what lobsters feel when they are injured, so I think it's important that we err on the side of caution. Thanks for commenting.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

Hi, Peggy. Yes, the whole idea of killing animals for food makes me very uncomfortable. I think the best situation for animals and for people who want to eat meat and its nutrients is to ensure that the animals are raised (or caught) humanely and also killed humanely. Thanks for the vote and the share.

John Sarkis from Winter Haven, FL on March 07, 2012:

I love lobsters, they're probably my favorite food of all. I've paid quite a bit for them, especially in Chinese restaurants.

Thanks for writing an article about "the other side of lobsters!"

Voted up


CMHypno from Other Side of the Sun on March 07, 2012:

Fascinating hub on lobsters Alicia. I remember I was horrified when I was in a restaurant in Miami Beach when I was told that they ripped the claws off the lobsters and then threw them back into the sea. Apparently it takes a year or so to grow a new set, and they rip those off and go through the process again. Can you imagine how defenceless a lobster must be on the seabed without its claws?

Peggy Woods from Houston, Texas on March 07, 2012:

"In any case, since no scientist can guarantee that lobsters can't feel pain the onus should be on us to kill them humanely if we want to eat them."

I'm with you on this statement, Alicia. When I first read about how old lobsters can grow to be and that they also congregate in family units, I quit eating them. I know that since I still eat meat and other forms of fish, that might be considered silly...but to this day, the thought of boiling a lobster when it is alive...I just cannot do it or be responsible for it being killed in that way.

Fantastic hub all about the lobster. Up votes and will share with my followers.

Linda Crampton (author) from British Columbia, Canada on March 07, 2012:

104 is a great age to reach, Perspycacious! I hope your Mom's birthday celebration is a very enjoyable event. Thank you so much for the comment and the votes - I appreciate them all!

Demas W Jasper from Today's America and The World Beyond on March 07, 2012:

Coming from Maine as I do, and with my Mom looking forward to her next birthday and a lobster feast at age 104, this fantastic discussion of this one of our favorite foods will circulate throughout our family! In Utah crayfish/crawdads are my "poor man's substitute" and one of God's creations which seeks to compete with their larger relative for the gourmet's championship. Up and all but funny...though the lobster's visual appearance suggests I may have omitted enough credit for the fine photos!

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