The chalk grouper living in small coral reefs in the Caribbean can change sex up to 20 times a day.
According to behavioral ecology, fish use an “egg swap” spawning strategy, which means laying eggs in the hole and then alternating sex with their partner during spawning.
Mary Hart, an environmentalist at the University of Florida, United States, said chalk fish rarely lay two consecutive eggs before changing sex with a partner. This helps to maintain cooperation between them and reduce the risk of fraud.
Most hermaphrodites change their sex at some stage in their development. This is a case of sequential hermaphrodites. Transformation is often driven by social and behavioral influences. For example, when a dominant man dies. Chalk, however, is able to simultaneously produce male and female gametes (sperm and ova).
Although the concomitant hermaphroditis does not only occur in chalk, it is still rare because the fish do not self-fertilize. Why chalk fish have changed their gender so many times remains a mystery, Hart says.
However, Hart argues that it could provide a spawning benefit for the fish. Sexual transitions allow them to fertilize your partner’s eggs. This improves the chances of passing genes to the next generation of each individual.
“There are about 2% hermaphrodites, of which the hermaphrodite species are only a very small part. In addition, many other simultaneous hermaphrodites live on the high seas and are difficult to study,” explains Eric. Says Fischer, an evolutionary environmentalist. This study may provide information on the spawning morphology of chalk fish as well as other hermaphrodites.
Hart studied at the Smithsonian Tropical Research Institute, Panama for six months. During the research, Hart found that the chalk fish were “faithful.”
“They stay with their partner for six months, until one of them is separated from the social community,” she said.
