The mouth is small with teeth that are formed into three pairs of non-replaceable tooth plates, two pairs in the upper jaw and one pair in the lower jaw. The four gill openings on each side of the head are covered by a fleshy operculum.
CHIMERA FISH SKIN
The skin is smooth and rubbery, completely lacking in scales or denticles. They range in size from small, slender-bodied fishes of 1–2 ft in total length (about 30.5–61 cm), to massive fishes, nearly 4 ft in length (122 cm), with gigantic heads and large girth. Physical characteristicsĬhimaeras are characterized by large heads and elongate bodies that taper to a whip-like tail. As of 2002 there are 33 described species of chimaeras with at least 10 additional species that are known, but not yet formally described. The plow-nosed chimaeras of the family Callorhinchidae have a delicate flap of skin in the shape of a hoe projecting from the snout the long-nosed chimaeras of the family Rhinochimaeridae are characterized by elongate, pointed snouts and the ratfishes, family Chimaeridae, have blunt fleshy snouts. Within the Order Chimaeriformes there are three families, each of which is distinguished by a unique snout morphology. What is especially remarkable is that many of the modern forms look very much like their fossil ancestors. Fossil evidence indicates that the chimaeras probably evolved nearly 300 million years ago. All chimaeras, sharks, skates, and rays are united in the class Chondrichthyes, which is further subdivided into two subclasses: Holocephali, consisting of the chimaeras characterized by a unique jaw and tooth morphology, and the Elasmobranchii, which includes the sharks, skates, and rays. The chimaeras are an ancient lineage of cartilaginous fishes related to sharks, skates, and rays.
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