There are some interesting facts about shrimp, one of which is, these animals are initially born male then later in development turn into a female.
Many species of shrimp spend their lives as both male and female. Shrimp are born as males, then later in life (in seasonal or annual cycles) their male gonads (sexual organs) descend, and are replaced by ovaries.
As newborn females, they will mate with younger males who have not yet transitioned. Have time to grow and develop, giving the female shrimp an advantage in reproduction and overall helping with population control.
Peppermint shrimp is one example of this. It is named peppermint, because along its body are translucent red stripes, making it look like peppermint candy.
But, as quoted from New Scientist, most peppermint shrimp prefer to remain male. All male shrimp are more successful in finding a mate than hermaphrodites (both sexes) who act as males. Perhaps because they can try harder to find a mate, and they will delay changing sex if there are other hermaphrodites.
Interestingly, the decision to change gender or not is determined by the size of the social group. To maximize their chances of one day mating, the prawns live alone and then turn into hermaphrodites, although they eventually grow more slowly due to the energy expended on making eggs.
Junda Lin of the Florida Institute of Technology in Melbourne, Florida, United States, has spent more than 10 years studying peppermint shrimp. His latest study shows that being male is not very beneficial for shrimp.
Although males require significantly less energy to make sperm than eggs, mating itself is "expensive" as the male must find a hermaphrodite mate and then pursue it for up to eight hours.
As a result, single mating can cost about 15% of the male's physical growth he would otherwise have achieved. This means that mating males grow more slowly and eventually become smaller than hermaphrodites, which often outgrow them for food.
Turning into a hermaphrodite might seem a natural extension of that strategy. After all, hermaphrodites can mate with anyone available, and so should have the best chance of passing on their genes.