Although you and I are born with a specific gender and have to stick with it for the rest of our lives, some animal species have an innate ability to trade gender roles on demand because they have both male and female reproductive organs already present in their bodies.
One such species is the chalk bass, which can reportedly change its gender up to 20 times per day, switching gender roles with its partner to greaten the odds of reproductive success, a study published in the journal Behavioral Ecology explains.
As National Geographic explains, the process is known as ‘egg trading’ which is essentially where while laying eggs, the fish divide the eggs into parcels before laying them and then switch their genders repeatedly to try and fertilize each other’s eggs.
During the process of switching their gender, the chalk bass would help ensure commitment by taking turns fertilizing each other’s’ eggs, as one would have to reciprocate to the other until the process was complete.
Mary Hart, an ecologist for the University of Florida, explained that it’s very unusual for animals, even those of the simultaneous hermaphrodite kind, to switch their genders so often in such a short period of time, but also notes that the feature isn’t unique to chalk bass and they do not self-fertizlie their own eggs.
Another fun fact, the chalk bass seemed to be very loyal to one another despite not being a monogamous species.
“All of the fish that I marked in the first month were together for the entire six months until one or both of them disappeared from the social group,” Hart explained.
Chalk bass are certainly an oddity in terms of their reproductive process, as it’s relatively uncommon for animals of any species to do what they do. Nevertheless, it may provide reproductive advantages and could explain why they’re still around today.
Source: National Geographic