Fish Mimics Fish-Mimicking Octopus

The black-marble jawfish takes advantage of its coloring to blend in with an octopus and stay safe from predators

A good eye will spot the black-marble jawfish next to the mimic octopus's arm
A good eye will spot the black-marble jawfish next to the mimic octopus's arm Godehard Kopp

The mimic octopus (Thaumoctopus mimicus) has the uncanny ability to make itself look like more dangerous creatures, such as lionfish, sea snakes and soles. The octopus does this with its distinctive color pattern and ability to adjust its shape and behavior (see this earlier blog post on the octopus for a video in which it mimics a flatfish). But now the mimic has a mimicker of its own, scientists report in the journal Coral Reefs.

Godehard Kopp  of the University of Gottingen in Germany was filming a mimic octopus during a diving trip to Indonesia last July when he spotted a companion–a small fish that followed the octopus for several minutes, always sticking close to the octopus’s arms. Kopp has some good observational skills, because the fish’s color and banding looks incredibly similar to that of the octopus.

Kopp sent his video (see below) to two marine scientists at the California Academy of Sciences who identified the fish as a black-marble jawfish (Stalix cf. histrio). The three write:

Jawfish are poor swimmers and usually spend their entire adult lives very close to burrows in the sand, to where they quickly retreat, tail first, upon sight of any potential predator…., the Black-Marble Jawfish seems to have found a safe way to move around in the open. The Mimic Octopus looks so much like its poisonous models that it is relatively safe from predation, even when swimming in the open, and by mimicking the octopus’ arms, the Jawfish seems to also gain protection.

This might at first glance appear to be a case in which the fish evolved its coloring to gain protection by associating with the octopus, but the scientists don’t think that’s likely. The jawfish can be found from Japan to Australia, but the octopus lives only in the region around Indonesia and Malaysia. They contend that this is a case of “opportunistic mimicry,” in which the fish is taking advantage of a happy coincidence.

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