Clownfish Change Size And Sex To Move Up The Ranks

What the movie "Finding Nemo" doesn't tell you about clownfish is that they're all transsexuals. In a study published in the journal Nature, evolutionary biologist Peter Buston and colleagues report that clownfish in Papua New Guinea reefs can change their sex at will for social reasons. Clownfish live in strict hierarchical communities. Each neighborhood is dominated by a top-ranking female breeder. Her male partner is next, followed by up to four progressively smaller, non-breeding fish. When the dominant female dies, her mate changes sex and becomes female. The top-ranking non-breeder becomes a sexually active male, and all the other fish shift up a rank. Clownfish also appear to regulate their size in order to remain part of the group. Each fish keeps its body mass 20 percent smaller than the fish directly above it in social rank, probably to avoid conflict. Fish who disrespectfully outgrow their rank are rejected by the clan.

Source <www.flmnh.ufl.edu>