The chalk bass is able to swap its own sex multiple times per day.
The Caribbean is often known for its mystery and enchantment. From pirates in movies to treasure-laden sunken ships to islands with never-want-to-go-home beaches and weather, there is no question the Caribbean is a world all its own. Take for example, the chalk bass. This small fish is native to the Caribbean waters and has a unique capability that is hard to comprehend.
New studies have shown that the three inch long chalk bass is capable of switching its sexual identity as many as 20 times per day. Utilizing a reproductive strategy known as egg trading, the chalk bass will switch gender roles with their mating partner throughout the spawning process.
Chalk bass tend to choose a reproductive partner and stick with that partner for a long period of time. While single fish will attempt to interrupt the mating process, most chalk bass will return to the same partner daily. More unique than the devotion to a single partner is the switching of reproductive roles by the two fish.
The chalk bass will parcel its daily egg clutch and rotate the laying and fertilizing of the eggs between partners. Surprisingly, this changing of roles and reciprocity between partners is an attempt to prevent cheating. According to a study led by Mart Hart, an evolutionary ecologist at the University of Florida, many of the fish could be seen with the same partner over the duration of the six month study.
Even though the fish possess hermaphroditic capabilities, they do not self fertilize. The small bass will lay eggs as well as fertilize eggs, but will not fertilize eggs they themselves have laid. Hart hypothesizes that, by switching genders, both fish improve the odds of passing their genes on to the next generation of chalk bass. This mutually beneficial practice is a rare find in nature, with only about 2 percent of fish being hermaphroditic. Even more rare, simultaneous hermaphrodites, like chalk bass partners, are limited to a small number of species. Most of these species are deep-sea fish that are difficult to study.