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chimaera

[ki-meer-uh, kahy-]

chimaera, cartilaginous marine fish, related to the sharks. Also called ratfishes, chimaeras are found in temperate oceans throughout the world, mostly in deep water. They have large heads, long, thin, ratlike tails, and large, fanlike pectoral fins. In many species there is a poison spine in front of the first dorsal fin. Their slippery skins are black, gray, or silver, often with stripes or spots. The largest reach a length of about 61/2 ft (2 m). Chimaeras resemble sharks in certain fundamental respects: They have cartilage skeletons, males have claspers for internal fertilization of females, and females lay eggs encased in leathery cases. However, they resemble the bony fishes in having the upper jaw fused to the skull, the gill slits opening into a single chamber, a bony covering, or operculum, over the gill slits, and separate anal and urogenital openings. A distinctive feature of chimaeras is the presence of extra claspers in the male, one in front of each pelvic fin and a prominent one on the forehead. The function of these appendages is not known, but they are thought to play a role in courtship. Chimaeras form the subclass Holocephali of the phylum Chordata, subphylum Vertebrata, class Chondrichthyes.

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Licensed from Columbia University Press

chimera

or chimaera

Any of the 28 species of ancient fishes constituting the subclass Holocephali (class Chondrichthyes), found in temperate to cold waters of all oceans. Like sharks and rays, chimeras have a skeleton of cartilage rather than bone, and the males possess external reproductive organs (claspers). They have a single external gill opening, covered by a flap as in the bony fishes, on each side of the body. Males have a supplemental clasping organ that is unique among fishes. Chimeras have large pectoral and pelvic fins and two dorsal fins, the first preceded by a sharp spine. They range in length from 24 to 80 in. (60 to 200 cm) and in colour from silvery to blackish. They inhabit rivers, estuaries, coastal waters, and open ocean to depths of 8,000 ft (2,500 m) or more. They eat small fishes and invertebrates.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

Chimera

In Greek mythology, a fire-breathing female monster. Its foreparts resembled a lion, its middle a goat, and its hindquarters a dragon. It devastated the land around Caria and Lycia until it was killed by Bellerophon. The word is now often used to denote a fantasy or a figment of the imagination.

Learn more about Chimera with a free trial on Britannica.com.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

Chimaera

Chimaeras are cartilaginous fish in the order Chimaeriformes. They are related to the sharks and rays, and are sometimes called ghost sharks, ratfish (not to be confused with the "rattails"), or rabbitfishes.

Chimaeras live in temperate ocean floors and grow up to two meters long. Like other members of the class Chondrichthyes, chimaeras have a skeleton constructed of cartilage. Their skin is smooth and lacks scales, and their color can range from black to brownish gray.

For defense, most chimaeras have a venomous spine located in front of the dorsal fin.

Chimaeras resemble sharks in some ways: they employ claspers for internal fertilization of females and they lay eggs with leathery cases. They differ from sharks in that their upper jaws are fused with their skulls; they have separate anal and urogenital openings; and they lack the many sharp and replaceable teeth of sharks, having instead a few large permanent grinding tooth plates.

Albino Puget Sound ratfish

A rare albino Puget Sound ratfish was discovered near Whidbey Island, Washington. It is the only pure albino among the 7.2 million specimens in the University of Washington's fish collection.

Gallery

Classification

In some classifications the chimaeras are included (as subclass Holocephali) in the class Chondrichthyes of cartilaginous fishes; in other systems this distinction may be raised to the level of class. Chimaeras also have some characteristics of bony fishes.

There are about forty species in six genera and three families:

Family Callorhinchidae