chimaera

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 6 1/2 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.

chimaera An organism composed of tissues that are genetically different. Chimaeras can develop if a mutation occurs in a cell of a developing embryo. All the cells arising from it have the mutation and therefore produce tissue that is genetically different from adjacent tissue, e.g. brown patches in otherwise blue eyes in humans. Graft hybrids are examples of plant chimaeras.

chimaera (ratfish or ghost shark) One of about 28 species of cartilaginous, deep-sea fish with a long, poisonous, dorsal spine and a slender tail. An oil, derived from its liver, is used as a lubricant. Length: 60cm–2m (23–80in). Families Chimaeridae, Collorhinchidae and Rhinochimaeridae. The term also refers to an animal formed from several different embryos.