newscientist.com – by Chelsea Whyte
Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world
Species: Cirrhitichthys falco
Habitat: Kuchino-Erabu Island in southern Japan, swapping sexes effortlessly
When it comes to selecting mates, hawkfish keep their options open. The flamboyantly coloured reef dwellers start life as females but can transform into males after maturing. Many marine animals do this, but these fickle fish have a rare trick up their fins: they can change back when the situation suits.