The Mimic Octopus Can Impersonate Over 15 Different Species and Scientists Are Still Finding New Ones

There is an octopus that lives in muddy river mouths off the coast of Indonesia and the broader Indo-Pacific. When a predator shows up, it does not hide. It does not squirt ink. It looks at the predator, makes a quick assessment, and turns itself into a completely different animal. Not always the same animal. A different one depending on what is approaching and what that particular predator is afraid of. Scientists have confirmed at least 16 different species it can impersonate. Possibly more. They are still working on it.

How It Actually Works

The octopus’s scientific name is Thaumoctopus mimicus, which roughly translates as “wonderful mimicking octopus,” and whoever named it was correct. Its normal state is a boring pale beige. When it decides to impersonate something, it rearranges its entire body.

Flatten itself out and undulate its arms symmetrically near the seafloor and it looks like a flounder. Pull six arms in tight and extend two in banded patterns and ripple them: banded sea snake. Spread all eight arms and hover with them fanned out: lionfish, with the color stripes to match. Each impersonation combines color change, body shape, arm arrangement, and specific movement patterns. It is not just changing color. It is performing a character.

The confirmed list includes flounder, sea snake, lionfish, stingray, cuttlefish, brittle star, jawfish, blenny, mantis shrimp, ghost crab, hermit crab, jellyfish, and sand anemone. Divers keep reporting additional ones that have not been formally studied yet.

Why It’s So Cool

Most animal mimics do one thing. Stick insects look like sticks. Leaf insects look like leaves. The mimic octopus has a repertoire, and it selects from it based on context.

Scientists watched one being harassed by territorial damselfish and chose to impersonate a banded sea snake. Banded sea snakes prey on damselfish. The octopus looked at what was annoying it and picked the specific thing that species fears. From a library of at least 16 options. In real time.

This is a creature with a brain the size of a walnut that lives for less than a year. It is making contextual predator-specific decisions about which disguise to deploy. Scientists observed it shifting between impersonations mid-journey as it crossed open seafloor, adapting as it went. Before 1998, nobody knew any animal on Earth did this.

Why Nobody Found It Until 1998

The mimic octopus lives in muddy river mouths and estuaries, which are not the kind of habitat marine biologists traditionally dived in depth. Most interesting marine life lives on reefs. Scientists followed the interesting marine life to the reefs. The muddy flats got largely ignored.

This is also exactly why the octopus evolved this strategy. In a reef, an octopus can find a crevice and hide. On an exposed sandy flat, there is nowhere to go. The mimicry replaced the need for cover. Instead of hiding, it became something scarier. And it did this so effectively that it walks across open seafloor in broad daylight without appearing particularly stressed about it.

Scientists think there are probably related species doing similar things in other muddy, understudied estuaries across the Indo-Pacific. Those habitats remain largely unexplored. The mimic octopus was found by accident in a place nobody was specifically looking.

The ocean is enormous and most of it is muddy at the bottom and we have looked at a very small percentage of it carefully. The mimic octopus is what turned up when someone finally looked at one muddy Indonesian river mouth.