Hypoplectrus

Hamlets are simultaneous hermaphrodites (or synchronous hermaphrodites): They have both male and female sexual organs at the same time as an adult, meaning that they function as a male and female, making them one of the few vertebrates that are male and female at the same time. They seem quite at ease mating in front of divers, allowing observations in the wild to occur readily. They do not practice self-fertilization, but when they find a mate, the pair takes turns between which one acts as the male and which acts as the female through multiple matings, usually over the course of several nights. Hamlets preferentially mate with individuals of their same color pattern.^[2]

There are currently 20 recognized species in this genus: