1911 Encyclopædia Britannica/Parrot-Fishes

PARROT-FISHES, more correctly called Parrot-Wrasses, marine fishes of the family Scaridae closely allied to the wrasses or Labridae. The family contains eight genera of which the principal are Scarus, Pseudoscarus, Odan and Sparisama. They are easily recognized by their large scales, of which there are from twenty-one to twenty-five in the lateral line, by having invariably nine spines and ten rays in the dorsal fin and two spines with eight rays in the anal, and especially by their singular dentition, of jaws as well as pharynx. The teeth of the jaws are soldered together, and form a sharp-edged beak similar to that of a parrot, but without a middle projecting point, and the upper and lower beak are divided into two lateral halves by a median suture. In a few species the single teeth can be still distinguished, but in the majority (Pseudoscarus) they are united into a homogeneous substance with polished surface. By this sharp and hard beak parrot-fishes are enabled to bite or scrape off those parts of coral-stocks which contain the polypes or to cut off branches of tough fucus, which in some of the species forms the principal portion of their diet. The process of triturating the food is performed by the pharyngeal teeth, which likewise are united, and form plates with broad masticatory surfaces, not unlike the grinding surface of the molars of the elephant. Of these plates there is one pair above, opposed to and fitting into the single one which is coalesced to the lower pharyngeal bone. The contents of the alimentary canal, which are always found to be finely divided and reduced to a pulp, prove the efficiency of this triturating apparatus; in fact, ever since the time of Aristotle it has been maintained that the Scarus ruminates. Nearly one hundred species of parrot-fishes are known from the tropical and sub-tropical parts of the Indo-Pacific and Atlantic Oceans; like other coral-feeding fishes, they are absent on the Pacific coasts of tropical America and on the coast of tropical West Africa. The most celebrated is the Scarus of the Mediterranean. Beautiful colours prevail in this group of wrasses, but are subject to great changes and variations in the same species; almost all are evanescent and cannot be preserved after death. The majority of parrot-fishes are eatable, some even esteemed; but they (especially the carnivorous kinds) not unfrequently acquire poisonous properties after they have fed on corals or medusae containing an acrid poison. Many attain to a considerable size, upwards of 3 ft. in length.