Wonderpus and Mimic Octopus Facts: Fascinating Mollusks
Beautiful and Surprising Animals
The beautiful and amusingly named wonderpus octopus is a vividly patterned, long-armed creature that lives in the shallow ocean water around Indonesia and Malaysia. The animal is a popular photographic subject for divers and has the very apt scientific name of Wunderpus photogenicus.
The wonderpus octopus is often confused with the mimic octopus (Thaumoctopus mimicus). This animal lives in the same general area and has a somewhat similar pattern of white spots and bands on a darker background. The mimic octopus has the amazing and almost instantaneous ability to change its color, skin texture, arrangement of the arms around the body, and style of movement in order to mimic other creatures.
The wonderpus octopus was officially recognized by scientists in 2006 while the mimic octopus was recognized in 1998. The ocean around Indonesia and Malaysia is proving to be very fertile ground for the discovery of new animals, some of which are spectacular.
Octopuses belong to the phylum Mollusca and the order Octopoda, which contains two suborders. The information about octopus biology given below applies to the suborder Incirrata, which contains animals with the familiar body form of an octopus. The suborder Cirrina contains octopuses with a slightly different body form and biology.
The Body of an Octopus
Octopuses are invertebrates. Unlike most other invertebrates, they are intelligent creatures with a brain and a well developed nervous system. They also have excellent eyesight. Experiments have shown that at least some octopuses can learn and that some seem to like playing with objects. Sadly, they have very short lifespans—from six months in some species to just a few years in others.
The mollusks have soft bodies, although they do have a hard structure in their mouth called a beak. This looks quite similar to a parrot's beak. An octopus uses its beak to bite its prey. Its mouth contains a tongue-like structure called a radula, which is covered by rasping denticles, or teeth.
An octopus's lack of hard, protective body parts could make it easy for predators such as large fish to attack it, so it needs camouflage techniques and the ability to move fast to protect itself. There is at least one advantage to having a soft body, though. It allows the animal to squeeze into tight spaces.
Internal Organs and Chromatophores
The mantle of an octopus is a thick layer of skin and muscle that forms a bag-like structure covering the organs. These organs include the three hearts, the digestive, excretory, and reproductive organs, and the gills, which are used for breathing. The mantle moves as water flows under its edge and over the gills, where oxygen is extracted from the water. The water then leaves the body through a tube called the siphon. An octopus can forcibly expel water out of the siphon. This action provides jet propulsion and enables the animal to move very rapidly.
Scientists have discovered that at least some octopuses inject a toxin into their prey as they bite it. They suspect that all species of the mollusk are venomous. Most are not dangerous to humans, however. The animals release a cloud of thick, dark "ink" from their ink sac to confuse potential predators and avoid becoming prey themselves.
The skin of octopuses contains a very high density of cells called chromatophores, which contain pigments. The chromatophores are controlled by the nervous system. As the chromatophores expand and contract they enable octopuses to alter their color or (as in the wonderpus octopus) to brighten and subdue the colors that are already present.
Octopuses of some species have been observed performing complicated courtship displays, which often involve color changes. During mating, the male uses a special arm called a hectocotylus to insert a sac of sperm into the female's mantle aperture. In a few species, the male's arm detaches during mating instead of being extended and then retracted. The eggs are fertilized inside the female's body and then laid.
Some females glue their eggs to the wall of a den and care for them until they hatch. Others, such as the female wonderpus octopus, attach the eggs to an arm and carry them around until they are ready to release the youngsters. In most of the octopus species that have been studied, the female dies soon after she has finished caring for the eggs. The male generally dies soon after mating.
The Wonderpus Octopus
The wonderpus octopus was discovered by scientists relatively recently. Since it doesn't live for long in captivity, there's still much that is unknown about its life. The animal is usually orange-brown or red-brown in color, with sharply defined white spots on its body and white bars on its arms. The colors and pattern become more dramatic when the animal is alarmed. Its “head” is branched. There's a small eye on each branch and a tall, vertical protuberance called a papilla above each eye.
Two theories have been proposed to explain why the wonderpus octopus developed its dramatic and conspicuous appearance. One theory suggests that the octopus is mimicking dangerous banded animals like sea snakes and lionfish as a form of protection against predators. Another theory says that it's warning predators that it's toxic.
The animal lives in a burrow on the ocean floor. This may be a burrow dug by another animal or a burrow dug by the octopus. The octopus emerges from its home to feed at dusk and at dawn. It moves by swimming or by using its arms to perform a walking motion over the ocean bottom.
Diet and Behavior
The wonderpus octopus is a predator and feeds on fish, crabs, and perhaps other crustaceans as well. Two methods of catching prey have been observed. The mollusk sometimes moves over the top of a potential prey animal and expands the webs attached to its arms to form an "umbrella" over the unfortunate creature. It then pulls the prey towards its mouth with an arm and eats it.
The octopus may also send one of its eight arms down into a hole like a probe, grabbing prey with the suckers on the underside of the arm. It has the ability to regenerate parts of arms that are lost and can deliberately release these parts to distract a predator.
The Mimic Octopus
The background color of a mimic octopus is often dark brown or black, while the wonderpus species generally has a light brown background tinged with orange or red. Both animals feed on fish and crustaceans, including crabs.
The ability of the mimic octopus to pose as other creatures is truly astounding, as shown in the videos below. So far it's been found to impersonate fifteen other animals, including fish, jellyfish, brittle stars, sea anemones, crabs, and shrimp. Furthermore, observations have shown that it chooses an appropriate animal to mimic in order to protect itself from a specific predator.
To mimic a poisonous flatfish, the octopus swims with its arms held together and streaming behind it and its body flattened. To mimic a toxic sea snake, it partially enters a burrow, leaving just two of its arms visible. It can swim in open water and change its movement style, suspending its arms in the water to resemble the dangerous fins of a lionfish. There are some claims that the wonderpus octopus also exhibits the latter two behaviors.
The mimic octopus can almost instantaneously change its color and the texture of its skin to help make its impersonations effective. Some octopuses can change color to merge with their background, but the mimic octopus is the first one known to mimic other creatures. Unlike the wonderpus octopus, Thaumoctopus mimicus is active during the day, so its excellent ability to impersonate other animals is very helpful for its survival.
A Fish That Mimics an Octopus
Researchers have discovered that the harlequin jawfish (Stalix histrio) mimics the mimic octopus. The coloration and pattern on the surface of the fish is very similar to that of the mollusk. Jawfish are interesting animals. They are mouthbrooders. The eggs stay in the adult's mouth until they hatch.
Stalix histrio lives in a burrow in the sand and is a timid creature. It quickly returns to its burrow when danger appears. It has been observed swimming very close to a mimic octopus. It often appears to be part of the animal's body, which means that it may not be detected by predators. The behavior of the fish when the mollusk changes its color needs to be studied.
Comparing the Mollusks
Apart from its enhanced ability to change color and mimic other creatures, the behavior of the mimic octopus seems to be very similar to that of the wonderpus octopus. It eats the same types of animals and uses the same methods to catch its prey. In addition, the female attaches her fertilized eggs to her arms, just as Wunderpus photogenicus does.
It might seem that it should be easy to distinguish a wonderpus octopus from a mimic octopus by color. Color isn't a consistently reliable way to differentiate between the two animals, however. This is due to individual variability and the fact that the underwater appearance of the animals is affected by the type of illumination that's shining on them. The ability of the mimic octopus to change color can also make identification difficult.
There seems to be a lot of confusion when people try to distinguish one mollusk from the other. Some of the observations that have been recorded about mimic octopus behavior may actually be observations of wonderpus octopus behavior and vice versa.
If the octopus is undergoing a dramatic color change in front of us we know that it’s a mimic octopus, but how else can we tell them apart, especially if a mimic octopus isn’t altering its color, texture, or pattern? Some methods are described in the table below.
Distinguishing a Wonderpus Octopus From a Mimic Octopus
Usually active in the early morning and in the evening
Usually active during the day
Separation between dark and light areas of skin is distinct
Separation between dark and light areas of skin is less distinct
Often has a light brown and white coloration
Often has a very dark brown and white coloration
Rear edge of mantle has a white spot
Rear edge of mantle has a white U or V shape
Eyes are on long stalks
Eyes are on shorter stalks
No white border on arm at base of suckers
White border on arm at base of suckers
The wonderpus and mimic octopuses are fascinating animals. It will be very interesting to see what else researchers learn about them. There are many unanswered questions about their lives and behavior as well as some points that need to be clarified.
Perhaps there are even more strange and wonderful creatures waiting to be discovered in the ocean near Indonesia and Malaysia. It appears to be a fascinating place to explore.
- Wunderpus octopus facts from the Monterey Bay Aquarium
- Individually Unique Body Color Patterns in Octopus (Wunderpus photogenicus) Allow for Photoidentification from Plos One
- Information about the mimic octopus from Nature Education
- Mimic octopus and harlequin jawfish facts from the American Museum of Natural History
Questions & Answers
We saw mating Wonderpus octopuses in Ambon, Indonesia. Is the male or female larger? Also, is one gender more colorful than the other?
There is still a lot to be learned about the Wonderpus octopus. A 2006 paper reported that females are larger than males. However, only two mature samples were measured. The sample size was very small, so the measurements may not be accurate. I've found no recent reports comparing the size of the genders, or describing any color differences between them.
© 2012 Linda Crampton