[3] They are synchronous hermaphrodites; ecologically and morphologically, all are remarkably similar in major features except for their color pattern which is how they are differentiated into different species.

[6] Shy hamlets were first formally described as Plectropoma guttavarium in 1852 by the Cuban zoologist Felipe Poey (1799–1891) with Havana given as the type of locality.

However, the extent of the two-color portions can vary, and they are divided by a diagonal line extending from the nape posteriorly and ventrally to the anal fin.

Until today, opinions of scientists remain divided concerning these two hypotheses and have been described as the "Hamlet Problem" by the American ecologist Ron Thresher.

In fact, studies have found that mating hamlets produce a unique sound while gametes are dispersed which might help to synchronize spawning.

[7] More recent work has suggested that there is some small degree of genetic isolation between geographically separated species, although it is not an absolute pattern.

They purposely choose a spawning location above a tall reef structure allowing them to mate relatively high in the water column.

This serves the purpose of placing the free-floating eggs in a location with higher chance to be carried away by the current to avoid being preyed upon by predators roaming the sea floor.