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The Monogamy Method

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There is considerable variety in social organization, locomotion, and other behavior among members of this group. General patterns characteristic of each family are presented here with some greater detail given to certain families. Goat-

fishes move purposefully along the bottom while foraging and may accompany other bottom-feeding or swimming species for opportunistic feeding, and other fishes, such as wrasses (Labridae), may join them for the same reason. Many goat-fishes aggregate in small groups, although members of certain genera, such as Mulloidichthys form large schools that seem to hover in the water column when not foraging on the bottom. Others move about singly, however, and some of these, such as Parupeneus cyclostomus (a species with two color morphs, golden yellow and pale blue), are remarkably active swimmers. Many species also rest upon the bottom for long periods of time, while some are more active at night than during daytime. The archerfishes use stealth when hunting prey in the manner discussed, but they may be territorial as they move back and forth encountering their neighbors. Galjoens move about in small groups, as do the sea chubs, although the latter can form exceptionally large groups that move about in the water column. The behavior of the jutjaws is poorly known, but they likely form aggregations or schools that swim in the water column. Sicklefishes do the same closer to the bottom. Monos form large schools in the mouths of rivers or in bays, but some occur singly or in small groups under the cover of mangroves in brackish water or brush in freshwater, where some species may be highly territorial.

The behavior of butterflyfishes, perhaps because of their bright coloration and high level of conspicuousness, has been the subject of considerable research. Largely diurnal, butter-flyfishes may occur singly and be highly territorial, or live in aggregations with a general home range and relatively little territorial or aggressive behavior. Most, however, may be found in pairs, usually monogamous, that patrol home ranges or protect shared territories. Territorial defense, in general, may be directed towards conspecifics, other butterflyfishes with similar feeding requirements or preferences, or other species of fishes that also share their diet. Species that live singly or in pairs may form aggregations during certain times of the day or season, and these may be related to reproduction. At least one species, Chaetodon lunula, which may form aggregations during daytime, is active at night.

Pyramid Butterflyfish Disease
Pyramid butterflyfish (Chaetodon polylepis) cluster over coral rocks near New Georgia Islands. (Photo by Fred McConoughey/Photo Researchers, Inc. Reproduced by permission.)
Archerfish (Toxotes jaculatrix) can spit water up to five feet (1.5 m) to knock insects into the water for a meal. (Photo by Animals Animals ┬ęStephen Dalton. Reproduced by permission.)

The angelfishes mostly form social and mating groups consisting of a single male and multiple females. They change sex from female to male (protogynous hermaphroditism), usually under social control. Some species may be monogamous or facultatively monogamous. For example, the emperor an-gelfish (Pomacanthus imperator) may often be encountered in pairs that consist of a male and female, yet additional females may reside in the pair's home range and join them prior to courtship at dusk. The regal angelfish (Pygoplites diacanthus) is often seen alone, but will form pairs or mating groups during sunset courtship periods. Some intra- and interspecific territorial behavior may occur, usually during encounters while patrolling a home range.

The behavior of the oldwife is not well known. Juveniles occur singly, but tend to form schools as they age. Adults are encountered either singly or in pairs, but large schools may also form. Shallow-dwelling boarfishes occur in pairs or small-to-large aggregations, depending upon the species, but the rarely seen juveniles occur singly. The behavior of their deep-water cousins, the armorheads, is poorly known, but they likely aggregate or form schools. The leaffishes are well known for the way they mimic leaves drifting in the water column. This allows them to avoid predation and to ambush potential prey. Little is known about the behavior of knife-jaws except that they swim about rocks and will enter caves.

The hawkfishes are territorial and organized socially into mating groups consisting of a single male and a variable number of females (usually two to five) that maintain territories or home areas inside the male's territory. Two species, however, are facultatively monogamous as a consequence of habitat use. For example, obligate coral-dwelling species, such as Oxycirrhites typus and Neocirrhites armatus, are facultatively monogamous if their coral (black coral or gorgonian sea fan, in the case of O. typus) is too small to support more than two fish, and if neighboring corals are too far away to allow a male to safely move to it to court a resident female. However, if the coral is large enough to support more than two fishes, or if suitable corals are close by, then a multiple-female group is possible. Juvenile obligate coral-dwelling hawkfishes often recruit to less-favorable corals nearby and then attempt, as do facultative and noncoral-dwelling species, to gain entry into the mating group. Usually, resident females will attack the new arrival and try to expel it from the coral or the group. This behavior is also directed towards adults, usually emigrants from fragmented groups elsewhere, that attempt to join the group. If the emigrant is recognized as another male, the resident male will attempt to expel it; if a female, it may be attacked by other females. As with other fishes that have a similar social organization, all hawkfishes likely change sex from female to male (protogynous hermaphroditism). Sex change may proceed through social control or maturation. The effect of sex change upon social organization can be profound, because, in addition to allowing for succession by the dominant female with the loss of the male, it can also allow the dominant female to fragment the group should it become too large for the male to control effectively. Similarly, if the dominant male cannot control his group, then neighboring males and "rogue" males (those that have lost a group or were recent females that could not fragment their own group after changing sex) can attempt to sequester females. Another interesting behavior is practiced by the plankton-feeding Cyprinocirrhites polyactis, which mimics fairy basslets (Ser-ranidae: Anthiinae) that aggregate, often in considerable numbers, in the water column.

Kelpfishes may establish large aggregations that form loosely over reefs, particularly surge zones, but individuals and small groups are more likely in the intertidal zone. The sea-carps also aggregate, either in small or large, loosely organized groups that rest upon the bottom. They swim with the dorsal fin raised when seeking food or changing location. Most morwongs move about the bottom singly or in small, loosely formed aggregations, but members of the genus Ne-madactylus form large aggregations. Trumpeters are mostly schooling fishes, which move about in small groups or in aggregations of hundreds of individuals.

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