Bizarre Facts: Sheephead Can Change Sex When Necessary.

California Sheephead fish are a funny-looking species. The males rock a white chin, large protruding canine teeth, and a very organized red and black body, while the females almost look like a large, slender goldfish. They are fascinating fish that play a vital role in maintaining the balance of kelp forests. Although male and female sheepheads look different, there is something about the fish’s sex that the two have in common— all sheephead are born female. Sheephead are sequential protogynous hermaphrodites meaning they begin life as females and will eventually become males. Even though they are born female, a sheephead can develop into a male when the ratio of males to females becomes unbalanced in a local population. According to the Monterey Bay Aquarium, as female sheephead get larger, they can produce more and more eggs. At some point, however, they could fertilize more eggs as a male than they could make themselves as a female. This reproductive pressure is potentially how sequential hermaphroditism evolved—as a case of biological economics. This may be why the switch is delayed when resources are plentiful— females can keep getting bigger and making more eggs. Teasing out the effects of social versus genetic control in gender...