Propagation of Reef Fish
247
"primary" males have a reddish-violet head, and the dorsal-caudal part of
the body is pale-pinkish with a big orange spot. When changing sex the
female acquires a new coloration resembling that of the "primary" males
(Shapiro 1981). The populations of the Caribbean parrot fish Scarus
croicensis include two differently colored forms. One is of monotonously
colored fish, which could be either females or "primary" males. The second
form - brightly coloured larger fish - are the "secondary" males transformed
from females which changed their sex.
The trigger mechanism which starts the change of sex by females of
protogynic fish is the deficiency of males in a given local group. It was
proved experimentally by removing several males a the group of typical
protogynic hermaphrodites. This action inevitably caused the change in
some females in the group to males, so that the balance of sexes was quickly
restored (Finshelson 1970; Robertson and Choat 1981). The same was
observed in the wrasse Thalassoma bifasciatum, the clown fish Amphiprion
melanopus, and the angel fish Centropyge interruptus (Shapiro 1979). The
change in sex by protogynic females could also be induced by injection of
testosterone (Ogden and Buckman 1973). If the testosterone was injected
into the "primary" males, they developed into specimens similar to
"secondary" males. In family groups of the cleaner wrasse, Labroides
dimidiatus, which consist of one leading "secondary" male, several females,
and several young fish, "primary" males are completely absent and only
females hatch from the eggs. The "boss" of the harem - that "secondary"
male guards the territory of the station, suppressing even its own females.
The feeling of being suppressed prevents their transformation into males.
But when the "boss" was withdrawn from this group, 1-2 h later the largest
female in the group took over his duty and assumed his behavior. After 2-3
weeks she changed her coloration and sex and became the "secondary"
male (Robertson 1972). These examples prove the interconnection of
adaptive social behavior and the physiological mechanisms of sex regulation
in hermaphroditic fish. Besides the above-mentioned, the following taxa of
her maphroditic reef fish could be mentioned: the groupers Hypoplectrus
chloronotus, H. pulella, Serranus subligarus, the chaetodontids from the
genus Contropyge, Holaranthus tricolor, the parrot fish from the genera
Scarus and Leptoscarus, the wrasses of the genera Halichoeres, Labrus,
Bodjanus rutus, Thalassoma duppery, and some others-totally over 30
species (Ross 1981; Robertson et at. 1982).
The reef fish resolve the method of propagation employing complex social
and territorial ecophysiological adaptations. These adaptations are seen
in the variability of the composition of spawning groups. The fish use
all possible combinations: temporary or permanent monogamic couples,
hurems, and collective spawning. As to the temporary couples, they are
formed by many medium-sized and big single predatory fish, like some
groupers, balistids, puffers, and reef sharks (Barlow 1975). To attract the
sexual partner for spawning these fishes often utter a kind of "mating call"
247
"primary" males have a reddish-violet head, and the dorsal-caudal part of
the body is pale-pinkish with a big orange spot. When changing sex the
female acquires a new coloration resembling that of the "primary" males
(Shapiro 1981). The populations of the Caribbean parrot fish Scarus
croicensis include two differently colored forms. One is of monotonously
colored fish, which could be either females or "primary" males. The second
form - brightly coloured larger fish - are the "secondary" males transformed
from females which changed their sex.
The trigger mechanism which starts the change of sex by females of
protogynic fish is the deficiency of males in a given local group. It was
proved experimentally by removing several males a the group of typical
protogynic hermaphrodites. This action inevitably caused the change in
some females in the group to males, so that the balance of sexes was quickly
restored (Finshelson 1970; Robertson and Choat 1981). The same was
observed in the wrasse Thalassoma bifasciatum, the clown fish Amphiprion
melanopus, and the angel fish Centropyge interruptus (Shapiro 1979). The
change in sex by protogynic females could also be induced by injection of
testosterone (Ogden and Buckman 1973). If the testosterone was injected
into the "primary" males, they developed into specimens similar to
"secondary" males. In family groups of the cleaner wrasse, Labroides
dimidiatus, which consist of one leading "secondary" male, several females,
and several young fish, "primary" males are completely absent and only
females hatch from the eggs. The "boss" of the harem - that "secondary"
male guards the territory of the station, suppressing even its own females.
The feeling of being suppressed prevents their transformation into males.
But when the "boss" was withdrawn from this group, 1-2 h later the largest
female in the group took over his duty and assumed his behavior. After 2-3
weeks she changed her coloration and sex and became the "secondary"
male (Robertson 1972). These examples prove the interconnection of
adaptive social behavior and the physiological mechanisms of sex regulation
in hermaphroditic fish. Besides the above-mentioned, the following taxa of
her maphroditic reef fish could be mentioned: the groupers Hypoplectrus
chloronotus, H. pulella, Serranus subligarus, the chaetodontids from the
genus Contropyge, Holaranthus tricolor, the parrot fish from the genera
Scarus and Leptoscarus, the wrasses of the genera Halichoeres, Labrus,
Bodjanus rutus, Thalassoma duppery, and some others-totally over 30
species (Ross 1981; Robertson et at. 1982).
The reef fish resolve the method of propagation employing complex social
and territorial ecophysiological adaptations. These adaptations are seen
in the variability of the composition of spawning groups. The fish use
all possible combinations: temporary or permanent monogamic couples,
hurems, and collective spawning. As to the temporary couples, they are
formed by many medium-sized and big single predatory fish, like some
groupers, balistids, puffers, and reef sharks (Barlow 1975). To attract the
sexual partner for spawning these fishes often utter a kind of "mating call"