Wrasses are in the family, Labridae, of marine fish, many of which are brightly colored. The family is very large and quite diverse with more than 600 species divided into nine sub groups. These groups vary tremendously in shape and coloration. They are typically small fish and are efficient carnivores, feeding on small invertebrates. However, some of species such as the Napoleon or Bumphead wrasse Cheilinus undulatus can grow up to two meters in length. Wrasses inhabit the tropical and subtropical waters of the Atlantic Ocean, Indian Ocean and Pacific Ocean as well as the Mediterranean Sea. They’re usually in shallow-water reefs and rocky shores although some species specialize in grassy beds.
General features of wrasses include thick lips, smooth scales, a long continuous dorsal and anal fin, and large teeth in the front of the jaw. Some species undergo fairly dramatic transformations in coloration over the course of their lifetime, as well as changing sex so they can be notoriously difficult to identify.
Breeding habits vary between the species but many wrasses are organized into harem-based social systems. Hermaphroditism is also common. Many wrasses have extremely complex aging stages. Some are all born as females changing sex at a later stage, while others remain separate sexes. Group spawning has also been observed.
Most wrasse are fast moving fish, using mainly their pectoral fins for propulsion. When threatened they will use their caudal fin for extra propulsion, to escape a predator or to catch prey. Wrasses will sometimes bury themselves in sand at the first hint of a threat. Some will sleep in the sand at night or hide in deep crevices. They are diurnal, feeding only during the day, and being fast moving fish, wrasses are voracious eaters to fuel their movement.
Wrasses spend a considerable amount of time searching for food. Their diets varies greatly. Smaller wrasses will follow larger fish to pickup crustaceans exposed by the wash of the larger fish, while others are plankton feeders.
Several species of wrasse act as cleaners for other fish, running so called cleaning stations. Fish will visit the cleaner station and the cleaner wrasse removes parasites and dead skin from the visiting fish in a symbiotic relationship. The most famous of these cleaners is the blue streak cleaner wrasse.