Many marine species have what are known as “sneaker males” - smaller males which deliberately look like females in order to avoid being attacked by a larger, more dominant rival. For one species of superbly sneaky cephalopod, however, the trick isn’t just a handy way of ensuring protection, but of procreation as well.

Australia’s mourning cuttlefish (Sepia plangon) takes the deception one mind-boggling step further by making maximum use of its ability to change colouration on demand. When a sneaker male cuttlefish is swimming between a female and a larger, more dominant male, it will split its look and display different skin markings and colours on either side of its body simultaneously. On the side facing the female object of its affection, it will display the typical male skin pattern of pulsating stripes, while on the other side facing the larger male, it will display the mottled camouflage characteristic of females. This means that it can appear male to the female and female to the male at the same time.

By being almost literally two-faced in this way, the sneaker thus fools his larger rival into thinking he's seeing two females instead of the surreptitious seduction going on under his metaphorical nose. It’s clear then, that there’s no such thing as chivalry amongst cephalopods, and that, in the aquatic world at least, cheaters can indeed prosper.