Video credit: Glenda Vélez Calabria (Colombia)
Review: Abdel Rahman El Gamal (Founder of the video channel)
This video was filmed at in mundo marino and te mostramos lo que pasa en el fondo, Colombia
Introduction: The bluehead, Thalassoma bifasciatum, is a marine species that belongs to the wrasse family (Labridae). The species is also known as bluehead wrasse and is also known as cabeza azul (in Spanish). Because of its small size, the species has no value to commercial fisheries, limiting its use to aquariums. The species rarely lives longer than two years, with a maximum reported age of 3 years.
Distribution and habitats: The bluehead is found in the western Atlantic Ocean from Florida (U.S.) to the Bahamas, southeast area of the Gulf of Mexico and northern South America. The species is very common in the Caribbean Sea. It also occurs in Bermuda and is most abundant throughout the West Indies.
The bluehead Inhabits coral reef, rocky flats, inshore bays and seagrass beds. While the young bluehead are abundant on shallow reefs, larger blueheads are found at deeper depths of up to 40 meters.
Description: On the average, bluefish are elongate and small fish of less than 11 cm (as a standard length) with a maximum reported length of 25 cm.
This attractive species is characterized by its three primary color phases which are namely initial (smallest), juvenile and terminal phase (largest). The colors, strips and blotches are characterizing these color phases. The habitats such as coral reefs may influence to colors compared to that in inshore non-reef habitats. The terminal phase coloration, which has a blue head, black and a green body giving the species its name.
Feeding habits: The bluehead forages mainly for zooplankton, mollusks, and other small benthic animals. Their feeding on the ectoparasites of other fish is a model of a symbiotic relationship in which the blue heads provide an important service to their customers of other reef fish by cleaning them of ectoparasites and dead tissues off their skin, scales, fins and gills as well as inside the mouth and between the teeth. The cleaning materials are considered a source of nutrients to bluefish. Adult blueheads may also feed on the eggs of small fish.
Reproduction: Group mating and individual mating are both performed in the reproduction of bluefish. In regard to the initial phase mating, group mating takes place in which each group consists of 20-50 males that congregate at specific sites. Females visit these groups to spawn and release their eggs in a ‘spawning rush’ whereas the large quantity of sperm released by males will be sufficient to fertilize the eggs laid by females especially young males usually have large testis. The larger blueheads spawn in pairs with a single female and a single male whereas a large male mates with one female at a time; a single male can typically mate with 30-50 females in a day.
The pelagic eggs hatch into about 12-mm after 18 and 24 hours after fertilization. After 6-8 weeks in the water column, they bury into the sand as they metamorphose into juveniles then after they turn into sexually mature at lengths as small as about 4 cm.
Blueheads may exhibit sex reversal. Small specimens are females, which change into males when growing. Their large schools are composed mainly of females with very few dominant males. If these males got absent for whatever reason, the largest female quickly changes sex, becoming a dominant male. This phenomenon insures the mating success within the school.
References: Wikipedia, FishBase, ICHTHYOLOGY, Marine species Identification Portal