Parrotfish

Parrotfishes are a group of about 90 species traditionally regarded as a family (Scaridae), but now often considered a subfamily (Scarinae) of the wrasses. They are found in relatively shallow tropical and subtropical oceans throughout the world, displaying their largest species richness in the Indo-Pacific. They are found in coral reefs, rocky coasts, and seagrass beds, and play a significant role in bioerosion.

Traditionally, the parrotfishes have been considered a family level taxon, Scaridae. Although phylogenetic and evolutionary analysis of parrotfishes is ongoing, they are now accepted to be a clade in the tribe Cheilini, and are now commonly referred to as scarine labrids (subfamily Scarinae, family Labridae). Some authorities have preferred to maintain the parrotfishes as a family-level taxon, resulting in Labridae not being monophyletic (unless split into several families).

Parrotfish are named for their dentition, which also is distinct from that of other labrids. Their numerous teeth are arranged in a tightly packed mosaic on the external surface of their jaw bones, forming a parrot-like beak with which they rasp algae from coral and other rocky substrates. Maximum sizes vary within the family, with the majority of species reaching 30-50 cm (12-20 in) in length. However, a few species reach lengths in excess of 1 m (3 ft 3 in), and the green humphead parrotfish can reach up to 1.3 m (4 ft 3 in).
 

Parrotfish Credit

A number of parrotfish species, including the queen parrotfish (Scarus vetula), secrete a mucus cocoon, particularly at night. Prior to going to sleep, some species extrude mucus from their mouths, forming a protective cocoon that envelops the fish, presumably hiding its scent from potential predators. This mucus envelope may also act as an early warning system, allowing the parrotfish to flee when it detects predators such as moray eels disturbing the membrane.
 

Although they are considered to be herbivores, parrotfish eat a wide variety of reef organisms, and they are not necessarily vegetarian. Species such as the green humphead parrotfish (Bolbometopon muricatum) include coral (polyps) in their diets. Their feeding activity is important for the production and distribution of coral sands in the reef biome, and can prevent algae from choking coral. The teeth grow continuously, replacing material worn away by feeding.