The incredible copycat abilities of the recently discovered “mimic octopus” have been documented in unprecedented detail in a scientific journal.
The 60 centimetre-long octopus was discovered in 1998 on the bottom of a muddy river mouth off the coast of Sulawesi, Indonesia. During dives over the next two years off Sulawesi and Bali, astonished scientists filmed nine different individuals repeatedly impersonating a sea snake, lionfish or flatfish.
“Those are the ones we are confident about,” says Tom Tregenza of Leeds University, one of the team led by Mark Norman at Melbourne University. “But it does do various other impressions that were only observed in only one octopus.”
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Other species of octopus possess amazing colour-changing abilities, and other animals are capable of impersonating one other species at certain points during their life cycles. But this it the first known animal that can morph between several different imitations.
On more than one occasion, the divers observed a mimic octopus shifting between impersonations as it crossed the ocean floor and returned to its burrow.
Poisonous intent
These species impersonated by the mimic octopus are all poisonous. “We believe that this extreme mimicry developed in this octopus as a means of tricking predators,” Norman told New Scientist.
Norman clearly linked a sea snake impression with the appearance of damselfish. These fish do not eat octopuses, but they are highly aggressive – and they are preyed upon by sea snakes.
Scientists have not spent long enough observing the mimic octopus to know what proportion of its time it spends pretending to be something else, Tregenza says. “But it might well go around doing these impressions all the time.”
He suspects that other supreme mimics are yet to be discovered: “The really amazing mimics are probably going to be found in what appear to be boring habitats. Something as complex as a coral reef provides such a lot of opportunities for hiding that the selective pressure for doing amazing impressions is going to be reduced.
“But muddy estuary bottoms in the tropics are not where people typically choose to go diving. These areas are virtually unexplored.”
Journal reference: Proceedings of the Royal Society of London B (vol 268, p 1)