IT is the ultimate in peer group pressure – coral reef fish that can change their sex depending on who they hang out with, scientists have discovered. A recent study by a team of Australian and American scientists have found changing sex is common among coral reef fish such as the juvenile bluehead wrasse. Dr Philip Munday, from Townsville's James Cook University, said the wrasse had adopted the unusual strategy so that each fish could increase its chances of breeding within a complex social structure. "It turns out that social effects are really important to whether a bluehead wrasse becomes...