GASTEROSTEIFORM

any member of the order Gasterosteiformes, a group of fishes characterized generally by soft fin rays, pelvic fins located on the abdomen, an air bladder without a duct to the gut, and a primitive kidney. Gill structures are somewhat degenerate. Most species have bony rings around the body or ganoid (i.e., thick, bony, enamelled, and diamond-shaped) plates rather than scales. Families within the order are Gasterosteidae (sticklebacks), Aulorhynchidae (tube snout), Indostomidae (indostomid), Aulostomidae (trumpet fishes), Fistulariidae (cornetfishes), Centriscidae (shrimpfishes), Macrorhamphosidae (snipefishes), Solenostomidae (ghost pipefishes), and Syngnathidae (pipefishes and sea horses). Gasterosteiform fishes occur in both salt water and freshwater and are widely distributed. The smallest species are about three centimetres (about 11/4 inches) long, the largest about 200 centimetres (about 80 inches). They are of limited economic importance, but many forms are popular aquarium fishes. Two families, Indostomidae and Aulorhynchidae, are represented by only one species each. any member of the order Gasterosteiformes, a group of bony, tube-mouthed fishes that contains well-known forms such as the sea horse, pipefish, and stickleback as well as the less familiar snipefish, tubesnout, shrimpfish, and ghost pipefish. Gasterosteiforms are of little economic value to humans except for the popularity of a few species as aquarium fish. Gasterosteiforms range in size from 3 cm (about 1 inch) to 200 cm (80 inches). They typically have soft fin rays, a swim bladder unconnected to the gut, pelvic fins located on the abdomen, and a covering of bony, ganoid plates. They are abundant in the waters of the Northern Hemisphere. Except for snipefishes, gasterosteiforms inhabit areas of dense aquatic plant growth. Their defensive behaviour generally consists of resting vertically among grasses, sea urchins, corals, and similar structures. This posture serves to camouflage the fish and presents its body spines to any predator. Sea horses use their prehensile tails to grasp vegetation and hold themselves in place; they can also use their swim bladder to rise or settle at different depths. Snipefishes can swim backward or forward equally well. Additional reading American Fisheries Society, A List of Common and Scientific Names of Fishes from the United States and Canada, rev. and enlarged, 4th ed. (1980); Leo Berg, Classification of Fishes Both Recent and Fossil (1947, reprinted 1980; originally published in Russian, 1947), English and Russian; W.A. Clemens and G.V. Wilby, Fishes of the Pacific Coast of Canada, 2nd ed. (1961), limited in breadth and depth due to few order representatives in that range; Earl S. Herald, Living Fishes of the World (1961, reprinted 1972); David Starr Jordan, Fishes, rev. ed. (1925), an excellent systematic work, although the nomenclature requires revision (college level); A.H. Leim and W.B. Scott, Fishes of the Atlantic Coast of Canada (1966), a work broader in scope than Clemens-Wilby (above); N. Tinbergen, The Curious Behavior of the Stickleback, Scient. Am., 187:2226 (1952), a popularized segment of the author's 1951 Study of Instinct; Gilbert Whitley and Joyce Allan, The Sea-Horse and Its Relatives (1958), a brief, supposedly popularized account of order members in Australian watersof amazing scope, interest, and depth.