246
Coral Reef Fish
causing a decrease in the number of fish specimens per one species and
so the decrease in the specific density of their populations. These
developments during the evolution of reef fish created definite complications
in the process of their breeding. Their different species solved these by
acquiring specific adaptations ensuring success in their multiplication
(Breder and Rosen 1966). Among these adaptations the following can be
mentioned: (1) formation of permanent monogamic couples in some gobies
and chaetodontids; (2) hermaphroditism and the ability in adult fish to
change sex; (3) selection of spawning sites hidden from predations; (4)
taking care of the eggs and larvae by some gobies, cardinals (Apogon) ,
damsels and syngnathids (Hudson 1977; Johannes 1978a; Shapiro 1977,
1979; Sale 1980; Tresher 1984).
The most remarkable features of multiplication of reef fish among those
listed above is the widespread hermaphroditism among them and the ability
of adult fish to change sex. This ability is peculiar for just to the typical reef
fish which form very rare populations. It could be found most often in
gobies, groupers, wrasses, parrot fish and chaetodontids. The change of sex
is a part of their complex social behavior purporting to even out the
disproportion during the formation of spawning couples. (Sale 1982). The
mechanisms of the sex changes are various. For example, in normal
hermaphrodites like the grouper Hypoplectrus most adult fish in the
population, or all of them, have well-developed milts and ovaries
simultaneously. Depending on the ratio between males and females in a
given spawning school they might function as males or as females (Barlow
1975). In the synchronous hermaphrodides (grouper Serranus subligarus)
both glands may function simultaneously accomplishing self-fertilization.
But most often the case in hermaphroditic fish is protogyny, i.e., the change
of sex by the adult females which, if necessary, can function as males
(Reinboth 1973). In local populations of these fish the females dominate.
Rarer is the case of protoandry, i.e., the change of sex by males to females.
It happens in hermaphroditic fish, which have a predominance of males in
local populations (Robertson 1972).
The change of sex by protogynie females to males is accompanied by
drastic changes in their coloration and even in the form and size of their
body. These secondary males, transformed from females, are so distinct
from the real ("primary") males that they happened to be described as a
separate species. The primary males in a population relate by numbers to
females ~ 1 to 20. Other males necessary for normal spawning of couples
come into being through the change in sex by females. In some species of
protogynic fish the "primary" males are completely absent, and all of the
males which participate in spawning, are of secondary origin (Shapiro 1979).
As an example of protogynic hermaphrodite fish the grouper Anthias
squamnupinnus could be mentioned. The primary males of this species have
a specific painting which drastically differs from the coloration of females:
females are an even golden-orange color with a reddish stripe. The
Coral Reef Fish
causing a decrease in the number of fish specimens per one species and
so the decrease in the specific density of their populations. These
developments during the evolution of reef fish created definite complications
in the process of their breeding. Their different species solved these by
acquiring specific adaptations ensuring success in their multiplication
(Breder and Rosen 1966). Among these adaptations the following can be
mentioned: (1) formation of permanent monogamic couples in some gobies
and chaetodontids; (2) hermaphroditism and the ability in adult fish to
change sex; (3) selection of spawning sites hidden from predations; (4)
taking care of the eggs and larvae by some gobies, cardinals (Apogon) ,
damsels and syngnathids (Hudson 1977; Johannes 1978a; Shapiro 1977,
1979; Sale 1980; Tresher 1984).
The most remarkable features of multiplication of reef fish among those
listed above is the widespread hermaphroditism among them and the ability
of adult fish to change sex. This ability is peculiar for just to the typical reef
fish which form very rare populations. It could be found most often in
gobies, groupers, wrasses, parrot fish and chaetodontids. The change of sex
is a part of their complex social behavior purporting to even out the
disproportion during the formation of spawning couples. (Sale 1982). The
mechanisms of the sex changes are various. For example, in normal
hermaphrodites like the grouper Hypoplectrus most adult fish in the
population, or all of them, have well-developed milts and ovaries
simultaneously. Depending on the ratio between males and females in a
given spawning school they might function as males or as females (Barlow
1975). In the synchronous hermaphrodides (grouper Serranus subligarus)
both glands may function simultaneously accomplishing self-fertilization.
But most often the case in hermaphroditic fish is protogyny, i.e., the change
of sex by the adult females which, if necessary, can function as males
(Reinboth 1973). In local populations of these fish the females dominate.
Rarer is the case of protoandry, i.e., the change of sex by males to females.
It happens in hermaphroditic fish, which have a predominance of males in
local populations (Robertson 1972).
The change of sex by protogynie females to males is accompanied by
drastic changes in their coloration and even in the form and size of their
body. These secondary males, transformed from females, are so distinct
from the real ("primary") males that they happened to be described as a
separate species. The primary males in a population relate by numbers to
females ~ 1 to 20. Other males necessary for normal spawning of couples
come into being through the change in sex by females. In some species of
protogynic fish the "primary" males are completely absent, and all of the
males which participate in spawning, are of secondary origin (Shapiro 1979).
As an example of protogynic hermaphrodite fish the grouper Anthias
squamnupinnus could be mentioned. The primary males of this species have
a specific painting which drastically differs from the coloration of females:
females are an even golden-orange color with a reddish stripe. The