Illustration by Alice Goodridge
On the list of changes to make in order to become male, colour doesn’t spring to mind for most people. But for cuckoo wrasse (Labrus mixtus) being bright blue and orange is essential for attracting females who prefer intensely coloured males. Every male cuckoo wrasse has made this transition, since every cuckoo wrasse is born female. When cuckoo wrasse reach 26cm long if there is a dearth of males in the area female wrasse become male.
About 5-20% of male cuckoo wrasse are indistinguishable from pinkorange coloured females in outward appearance and use a different tactic to breed. Instead of attracting mates, males clad in female colours sneak to nests built by standard blue-orange males where eggs have been laid and try to fertilise them. Ecologists call this ‘sneaky fucker strategy’ and point out that it shows how subordinate males can be successful.