Courtship is the series of behavioral actions performed by one or both members of a mating pair just prior to spawning. Courtship has several functions that maximize effi - ciency of the spawning act. Courtship aids in species recognition (a pre-mating species-isolating mechanism), pair bonding, orientation to the spawning site, and synchronization of gamete release. Courtship is often necessary to overcome territorial aggression by the male, who might otherwise drive the female away from the site (in many species, males already have eggs in their territories and must guard against predation by conspecifics of both sexes). Courtship may be relatively simple (as in herring), or may involve a large number or a complex progression of displays and signals by one or both members (e.g., Corynopoma, Characidae; Guppies; sticklebacks).
During courtship, individuals frequently change color from their normal, countershaded patterns to bolder, contrasting color patterns. In many species (e.g., minnows, silversides, cichlids) existing body coloration intensifi es or the head becomes dark relative to the remainder of the body. Sound production during courtship, usually by the male, occurs in many fish families (sturgeons, minnows, characids, codfishes, toadfishes, sunfishes, grunts, sciaenids, darters, damselfishes, cichlids, blennies, gobies), often in accompaniment with visual displays involving exaggerated or rapid swimming patterns, erection of fins, and jumping out of the water (Fine et al. 1977; Myrberg 1981, 2002; Lugli et al. 1997; Johnston & Johnson 2000; Lobel 2001; Johnston & Phillips 2003). Chemical stimulants are also involved. Male Goldfish, Zebra Danios (Cyprinidae), and gobies begin courtship activities when exposed to water that held a gravid female, and gravid female gobies are attracted to male-produced androgynous substances (Hara 1982; Stacey & Sorensen 1991). Species and sex recognition during courtship in cichlids occurs more quickly when individuals receive both visual and chemical cues from potential mates (Barlow 1992).
Some appreciation of the evolutionary premium placed on successful courtship can be gained by realizing that the gas bladder muscles that produce the boatwhistle mating call of the male Oyster Toadfish, Opsanus tau (Batrachoididae), contract at a rate of 200 Hz. This makes them the fastest contracting vertebrate muscles known, the next closest being the shaker muscles at the base of the tail of rattlesnakes, which contract at only half that rate (Rome et al. 1996).
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