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Taxonomy Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Octopodidae
Genus: Thaumoctopus
Subgenus: Thaumoctopus mimicus
Figure 1. Mimic octopus resting over a den.
Introduction
Thaumoctopus mimicus, also known as the mimic octopus, is a newly described species first discovered in the mid-1990s. These octopuses take advantage of unique and bold coloring, as well as unique behavior, to imitate and confuse potential predators.
Description/unique anatomy
T. mimicus is a small cephalopod, the maximum reported mantle length being 58mm, with long thin arms reaching 60cm. The body of the mimic octopus is dark brown with white stripes or spots, and it has a distinct white teardrop shaped ring on the dorsal side of its mantle.
It is unknown if the bold coloring of this species is indicative of poison or not. The majority of octopuses do not have bright color patterns unless they are toxic, so the presence of the distinct dark brown and white lead some researchers to believe that the mimic octopus may be poisonous to its predators. Either way, the bright coloration can certainly serve as a means of warning other animals away.
Figure 2. Mimic octopus in captivity.
Diet
The diet of the mimic octopus primarily comprises of worms, shelled molluscs, crustaceans, echinoderms, and fish. T. mimicus has been seen both actively hunting as well as foraging, typically during day, most often around sunrise and before sunset. They utilize their long arms to search along the sand and dig into tunnels made by their prey.
Geographic range The geographic range of T. mimicus was originally thought to be limited to Indo-Malaysian Archipelago, but more recently the species has been discovered from the Red Sea to New Caledonia, including the Great Barrier Reef in Australia.
The preferred environment of the mimic octopus is very flat and open, typically consisting of a silt or sand substrate. The majority of the time T. mimicus has been spotted in water with a depth of 2-20m. They have mostly been observed hanging out in dens or other holes in the sand, taking shelter in varying locations depending on where they were hunting or foraging. Strangely, this species has been spotted multiple times entering different tunnels in the sand while foraging.
Figure 3. Approximate known geographic grange of T. mimicus.
Reproduction
Not much is known about the life span or reproduction in this species, most of what is known is gleaned from knowledge of other octopuses or what has been seen in captivity. It is thought that this small octopus doesn’t live very long, an average lifespan in the wild may be a year. When reproducing male T. mimicus deposit their sperm into the mantle of the female using a specialized arm called a hectocotylus, and after fertilizing the female they die. Once the female lays her now fertilized eggs, she carries them with her in multiple strings, instead of depositing them in a nest like the majority of octopus species. Once the larvae hatch, the female octopus will die.
Mimicry
The majority of octopus species utilize camouflage to evade predators; in fact, once a predator is detected an octopus can change the appearance of its entire body in three-tenths of a second. This dynamic change isn’t limited to color, but can include skin texture by use of papillae. The skin papillae allows octopuses to mimic the bumpy, spiky, or smooth textures of the habitat around it. T. mimicus takes advantage of this traditional type of disguise when stationary, but also has its own unique approach.
Figure 5. T. mimicus imitating a flatfish.
See it in action here: https://youtu.be/H8oQBYw6xxc
Bibliography
Baker, Beth. “Unusual Adaptations: Evolution of the Mimic Octopus.” BioScience, vol. 60, no. 11, Dec. 2010, pp. 962–962., doi:10.1525/bio.2010.60.11.18.
Coker, Darren J. “Documentation of the Mimic Octopus Thaumoctopus Mimicus in the Great Barrier Reef, Australia.” Marine Biodiversity Records, vol. 6, 2013, doi:10.1017/s175526721200125x.
Courage, Katherine H. “Skin Deep: a Peek into the Octopus's Bag of Tricks.” Natural History, Sept. 2013, p. 30+.
Hanlon, Roger T., et al. “Mimicry and Foraging Behaviour of Two Tropical Sand-Flat Octopus Species off North Sulawesi, Indonesia.” Biological Journal of the Linnean Society, vol. 93, no. 1, 17 Jan. 2007, pp. 23–38., doi:10.1111/j.1095-8312.2007.00948.x
Hanlon, Roger. “Cephalopod Dynamic Camouflage.” Current Biology, vol. 17, no. 11, 2007, doi:10.1016/j.cub.2007.03.034.
Hemdal, Jay. “Aquarium Fish: Captive Observations of the Mimic Octopus, Thaumoctopus Mimicus.” Advanced Aquarist, Apr. 2007.
Hislop, Alexander. “Diving with Mimic Octopus.” Diving at The Great Blue Hole, Belize | Dive The World Vacations, Dive The World Blog, www.dive-the-world.com/creatures-mimic-octopus.php.
Norman, M. D., et al. “Dynamic Mimicry in an Indo-Malayan Octopus.” Proceedings of the Royal Society B: Biological Sciences, vol. 268, no. 1478, 2001, pp. 1755–1758., doi:10.1098/rspb.2001.1708.
Norman, M. D., et al. “Figure 1. ‘Mimic octopus’.” “Dynamic Mimicry in an Indo-Malayan Octopus.” Proceedings of the Royal Society B: Biological Sciences, vol. 268, no. 1478, 2001, pp. 1755–1758., doi:10.1098/rspb.2001.1708.
Sukhsangchan, Charuay, and Chaiyut Kaewchaichalearnkit. “First Captured Record of a Mimic Octopus (Thaumoctopus Mimicus) in Thailand.” Phuket Marine Biology, vol. 72, 2013, pp. 55–59.
Figure 1. Spencer, Erin. Mimic Octopus by Elias Levy. Why the Mimic Octopus is the Ultimate Master of Disguise, Ocean Conservacy, April 1, 2016, oceanconservancy.org/blog/2016/04/01/why-the-mimic-octopus-is-the-ultimate-master-of-disguise.
Figure 2. Hemdal, Jay. “Umbrella pose.”. “Aquarium Fish: Captive Observations of the Mimic Octopus, Thaumoctopus Mimicus.” Advanced Aquarist, April 2007, advancedaquarist.com/2007/4/fish.
Figure 3. Map taken from Google Maps.
Figure 4. Debus. Example of mimicry. Mimic Octopus (Thaumoctopus mimicus), Epic Creature, September 12, 2011, http://epiccreature.blogspot.com/2011/09/mimic-octopus-thaumoctopus-mimicus.
Figure 5. Spencer, Erin. Mimic Octopus by Klaus Stiefel. Why the Mimic Octopus is the Ultimate Master of Disguise, Ocean Conservacy, April 1, 2016, oceanconservancy.org/blog/2016/04/01/why-the-mimic-octopus-is-the-ultimate-master-of-disguise.
The mimic octopus gets its name from the predator avoidance behaviors it exhibits. T. mimicus utilizes dynamic mimicry and takes advantage of bold coloring and movements to imitate potential predators; specifically lion fish, sea snakes, and flatfish. The most involved mimicry involved is that of the poisonous flatfish. When pretending to be a flatfish, T. mimicus will flatten out its body, with all of its limbs flowing behind it. It even goes so far as to swim in the same pattern and speed as flatfish, making for quite the convincing imitation. If a predator isn’t fooled, it is at least confused long enough for the mimic octopus to escape. To imitate the lion fish, the octopus will splay out its limbs to look like the fish, even imitating the speed that the lion fish swims. When imitating sea snakes, the mimic octopus will extend to arm in opposite directions, and then bury the rest of its body in the sandy bottom of the ocean floor.
Figure 4. The first row of images show the mimic octopus (left) when imitating a flatfish (right). Second row images show T. mimicus (left) displaying the wide armed representation of the poisonous lionfish (right).The bottom row is an example of the mimic octopus (left) doing its impersonation of a sea snake (left).
Mimic octopuses take a risky approach to predator deterrence, rather than hiding behind its ability to camouflage with its surroundings, this species has evolved to have a bright and bold coloration that makes it easier to spot. Some scientists believe that T. mimicus developed this unique defense because of the environments it finds itself in, typically flat and open areas. Not many corals, rocky outcroppings, or large underwater forests to hide in. Instead, they have evolved to hide in plain sight, by imitating potential predators and other animals in its habitat.
The hows and whys of T. mimicus use of mimicry has been greatly debated. Until recently, it hasn’t been understood if the mimicry behavior was first learned or inherited. There is now DNA evidence that the mimic octopus’ ability to impersonate potential predators arose in multiple steps. First, the characteristic camouflage trait of octopuses developed, and with it, the bold color pattern unique to this species. Second, the ability to arrange its long arms in a flatfish shape formed. Third, the combination of its dark coloring, with bright white stripes, and the ability to imitate the way flatfish swim.
Interesting fact
Perhaps the most interesting fact about the mimic octopus is the debate surrounding the presence of its bright coloration and its mimicry behaviors. It is unknown if T. mimicus is a Mullerian mimic and the bright coloration is there to warn off predators that are vulnerable to its toxins, or if it is a Batesian mimic and the bright patterns are there to give credence to an otherwise non-poisonous imitation of a poisonous animal. In either case, by using dynamic mimicry T. mimicus has shown itself to be quite versatile animal, and able to discourage a variety of would-be predators by imitating multiple species like: the sea snake, jellyfish, flatfish, stingray, and lion fish.
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