by M.B.
Physiology
The Mimic Octopus is a master of camouflage. They grow to about 60 centimeters long (2 feet), and their natural skin pattern consists of beige and brown bands, although they often display dark brown and white bands instead.1 They also have fleshy growths that look similar to horns over each eye. The Mimic Octopus, along with other octopus, cuttlefish, and squid, belongs to the Cephalopoda class of the Mollusk phylum. Cephalopods are highly intelligent marine invertebrates easily recognizable by their tentacles and large mantles. Most have the ability to change the color of their skin. This is thanks to chromatophores, specialized skin cells filled with a pigment sac. Contracting muscles around the cell pull the pigment sac open, revealing more of the coloration. When the muscle relaxes, the sac shrinks back to its default, less visible state.2
Cuttlefish and Octopus especially are known for camouflaging into their environments. However, cephalopod eyes have only a single type of light receptor, making them colorblind.3 Their wide, u-shaped pupils allow light to enter their eyes from multiple directions and induce much more color blurring, or chromatic aberration, than humans experience with their small, round pupils. Cephalopods can change the distance between their lenses and retinas, allowing them to focus specific wavelengths of light.3 Though they’re colorblind, they can perceive, differentiate between, and mimic the colors they see.
Behavior and Feeding
Those features are shared by cephalopods, but the Mimic Octopus uses those abilities to disguise itself as other marine organisms. It resides in shallow offshore waters in the Indo-Pacific region, and it prefers muddy sea beds the same color as its natural skin.1 To avoid predation the Mimic Octopus takes on the appearance and movement of other animals in its environment. By spreading its tentacles away from its head, it imitates the banded spines of a lionfish. It can pull all but two of its limbs close and adopt the coloration of a sea snake. It can also draw water into its mantle, expand its head, and trail its limbs, imitating a jellyfish. The octopus can push its tentacles to one side and flatten its body like a flatfish. It completely mimics the swimming motion and speed as well.1 Most of the animals the octopus mimics are poisonous, warding predators away from it.4
The Mimic Octopus feeds on small fish and crabs. It can sneak up on prey and ensnare its target, but it also forages along the seafloor. It glides by drawing in and releasing jets of water from its siphon, and it uses its tentacles to reach into coral, crevices, and sand.1 The octopus can make use of its mimicry skills by bunching itself up and walking on two tentacles, taking on the appearance of a crab, and awaiting a ‘suitor,’ only to eat up any crabs who get close.1 It can tear up fish with its beak, but it can’t do the same for the crab’s hard shell. It bites down on the ensnared crab to inject a paralyzing neurotoxin and enzymes to break down the crab’s insides into an edible state.5
Umwelt
It’s time to find food. I crawl out from my hole in the ground, but I’m met with a bothersome fish. I’d rather have it leave me alone, so I’ll scare it. I pull most of my body back into the hole, but I leave two of my tentacles. With their dark and light bands, they look like a sea snake. The fish swims away, and I can proceed. I glide along the ocean floor, reaching under rocks and crevices but there’s nothing to grab. I need a better view, so I propulse myself upwards. I spread my tentacles out like a toxic fish’s spines, now no one will bother me. I see a small crab moving on the ground, small enough for me to eat. I descend and curl into myself to look smaller. The crab does not run away, and I can approach it. I grab it with my tentacles and pull it towards my beak, biting into it and enveloping it. The crab stops moving, and I proceed to slurp up it’s soft insides.
Bibliography
Bibliography:
1Mimic Octopus. (n.d.). Retrieved May 17, 2020, from https://eol.org/pages/3100227/articles
2Spencer, E., Spencer, E., Hogge, K., Brauner, E., & Moore, M. (2019, October 8). How do Octopuses Change Color? Retrieved May 17, 2020, from https://oceanconservancy.org/blog/2019/10/07/octopuses-change-color/
3Sanders, R., & Sanders, R. (2016, July 9). Weird pupils let octopuses see their colorful gardens. Retrieved May 17, 2020, from https://news.berkeley.edu/2016/07/05/weird-pupils-let-octopuses-see-their-colorful-gardens/
4Jereb, P., Roper, C. F. E., Norman, M. D., & Kinn, J. F. (2014). PDF. Rome.
5US Department of Commerce, & National Oceanic and Atmospheric Administration. (2011, July 5). How to Feed a Giant Octopus. Retrieved May 18, 2020, from https://oceantoday.noaa.gov/howtofeedagiantoctopus/