Grouper

General description:
Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes. Not all serranids are called groupers; the family also includes the sea basses. The common name grouper is usually given to fish in one of two large genera: Epinephelus and Mycteroperca. In addition, the species classified in the small genera Anyperidon, Cromileptes, Dermatolepis, Gracila, Saloptia, and Triso are also called groupers. Fish in the genus Plectropomus are referred to as coralgroupers. These genera are all classified in the subfamily Epiphelinae. However, some of the hamlets (genus Alphestes), the hinds (genus Cephalopholis), the lyretails (genus Variola) and some other small genera (Gonioplectrus, Niphon, Paranthias) are also in this subfamily, and occasional species in other serranid genera have common names involving the word "grouper". Nonetheless, the word "grouper" on its own is usually taken as meaning the subfamily Epinephelinae. Description:
Groupers are teleosts, typically having a stout body and a large mouth. They are not built for long-distance, fast swimming. They can be quite large, and lengths over a meter and weights up to 100 kg are not uncommon[citation needed], though obviously in such a large group, species vary considerably. They swallow prey rather than biting pieces off it. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth plates inside the pharynx. They habitually eat fish, octopuses, and crustaceans. Some species prefer to ambush their prey, while other species are active predators. Reports of fatal attacks on humans by the largest species, the giant grouper (Epinephelus lanceolatus) are unconfirmed.[6] Their mouths and gills form a powerful sucking system that sucks their prey in from a distance. They also use their mouths to dig into sand to form their shelters under big rocks, jetting it out through their gills. Research indicates roving coralgroupers (Plectropomus pessuliferus) sometimes cooperate with giant morays in hunting.[7]

Reproduction:
Groupers are mostly monandric protogynous hermaphrodites, i.e. they mature only as females and have the ability to change sex after sexual maturity.[8][9] Some species of groupers grow about a kilogram per year and are generally adolescent until they reach three kilograms, when they become female. The largest males often control harems containing three to 15 females.[8][10] Groupers often pair spawn, which enables large males to competitively exclude smaller males from reproducing.[8][11][12][13] As such, if a small female grouper were to change sex before it could control a harem as a male, its fitness would decrease.[11][12][13] If no male is available, the largest female that can increase fitness by changing sex will do so.[12] However, some groupers are gonochoristic.[8] Gonochorism, or a reproductive strategy with two distinct sexes, has evolved independently in groupers at least five times.[8] The evolution of gonochorism is linked to group spawning high amounts of habitat cover.[8][12][14] Both group spawning and habitat cover increase the likelihood of a smaller male to reproduce in the presence of large males. Fitness of male groupers in environments where competitive exclusion of smaller males is not possible is correlated with sperm production and thus testicle size.[10][12][15] Gonochoristic groupers have larger testes than protogynous groupers (10% of body mass compared to 1% of body mass), indicating the evolution of gonochorism increased male grouper fitness in environments where large males were unable to competitively exclude small males from reproducing.[10]