The mimic octopus (Thaumoctopus mimicus) is an expert impersonator, contorting its boneless body into a variety of shapes to effortlessly assume the forms of up to ten different marine species from lionfish to jellyfish to sea snakes and even crabs. But the sneaky cephalopod has been one-upped and the masterful marine mimic has itself been mimicked.

German scientists diving off the coast of Indonesia were stunned to discover that a tiny yellow-and-black striped fish was swimming alongside a similarly coloured mimic octopus, wiggling its body like a tentacle and deliberately following it so closely that it was initially mistaken for a ninth arm. The little copy-cat was a jawfish – a shy species that normally stays hidden in ocean burrows and has almost never been observed swimming out in the open.

The fish hitchhiked along with the oblivious octopus to take advantage of its camouflage and mask it from visual predators whilst looking for food or a new burrow. And while at first sight it appeared to be a harlequin jawfish, its unique behaviour (known technically as “opportunistic mimicry”), has lead scientists to question whether it may actually be a genetically distinct, previously undiscovered new species altogether...

Thank you for reading this week's edition of FIN ('Fascinating Ichthyological Nugget'): the easiest way to propel your aquatic knowledge! We sincerely hope that you'll find these of interest and want to share them with your friends…