IF YOU want to sneak into a harem, the best strategy is to dress up in drag.
At least, that鈥檚 the tactic favoured by male giant cuttlefish, which turn
transvestite to slip past other males guarding their mates.
Cuttlefish and their cousins octopuses and squid are masters of disguise,
transforming their colour, shape and texture to evade predators. The animals
also use these abilities in elaborate courtship displays. For instance, male
giant cuttlefish (Sepia apama) flash black and white stripes over their
bodies to attract the smaller, mottled females.
Large numbers of the cuttlefish gather to mate on rocky reefs at Spencer Gulf
in South Australia. Whilst watching the courtship behaviour of these animals,
Mark Norman of James Cook University in Townsville and Julian Finn of the
University of Tasmania in Hobart noticed that small males often tagged along
with breeding pairs in the guise of females. The males鈥� arms are usually fringed
with webs, but the smaller males can retract these to impersonate the females,
as well as adopting the female body colour and pattern.
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When the larger male is tied up fending off other rivals, the sneaky male
reveals his true colours in an often successful attempt to woo the female.
Furthermore, if the larger male returns to find his paramour flirting with the
sneak, the smaller male can rapidly don female disguise again to avert the wrath
of the spurned male (Proceedings of the Royal Society B, vol 266, p
1347).
It鈥檚 not just the cuttlefish that are fooled. The biologists also have a hard
time telling the impostors from the real females. 鈥淲e have to follow them and
see when they change back,鈥� says Norman and Finn鈥檚 colleague Tom Tregenza of the
University of Leeds, who studied their videos of the cuttlefish. He says that
although there are other male animals that mimic females, none can switch its
disguises on and off as easily.
The cuttlefish originally transformed itself as a means of camouflage and
only later turned to female impersonation, according to Tregenza. 鈥淥nce you鈥檝e
got those abilities, they start to come into play for something else.鈥�
But it鈥檚 unclear whether the transvestite males are undersized or simply
younger than those they cuckold鈥攍ater abandoning the strategy once they
are large enough to compete for mates openly. 鈥淭he larger males don鈥檛 need
to鈥攖hey can win contests with other males,鈥� says Tregenza.
There may now be an evolutionary 鈥渁rms race鈥� between the males, the
researchers suggest. Larger males may be developing better ways of spotting the
impostors, while the smaller males may be refining their disguise to overcome
this. 鈥淐ertainly there鈥檚 a potential pressure for the impersonation to get
better and better,鈥� says Tregenza. As very little is known about the mating
behaviour of cuttlefish, octopus and squid in the wild, transvestism may turn
out to be more widespread under the waves than anyone realised.