Feeding of Reef Fish
235
mulon, Eguetus acuminatus), Pomacentridae (Genus Chromis, Pomacentrus
coeletus, Amblygliphiodon curacao, Dascyllus reticulatus), Gobiidae (genera
Joglossus, Ptereleotris, Cottogobius), Chaetodontidae (Chaetodon sedentaris), Apogonidae (Apogon gracilis, A. novaeaquinea, A. savayensis, A.
binotatus), Holocentridae (Myripristis pralinus, M. jackobius, M. violaceus),
Cyrrithidae (Amblycirrithes pinos), and Congridae (Nystactichthys haila,
Gorgasia sillineri, Taeniconger halis). The families of reef planktonovorous
fish Atherinidae and Caesionidae descended from the perchiform fish. The
genera Aterina, Allanetta, Pranesus, Caesio and Pterocassio are among the
most common reef fish feeding on zooplankton (see Tables 6.8, 6.10,
6.13).
The morphological adaptations in the secondary planktonovores are
manifest largely in the changes of morphology of mouth parts. Their jaws
expanded and became tube-like. On opening, the mouth sucks water inside
as a pipette together with the zooplankters which the fish is hunting for.
Their teeth became tiny, the gills denser, the cranium bones thin, and the
eyes enlarged. The size of their body reduced and assumed a spindle-like
form. In some of these fish the morphological changes connected with
transition to plankton feeding were so deep, that they could easily be
accepted as representatives of another family, such as the serranid Schulzea
beta. There morphological changes were connected also with the transition
from single to schooling life, because within the schools the pressure of
grazing in the water column decreases (Davis and Birdsong 1973). With this,
too, is connected the coloration of the daytime planktonovores, which are
subjected to predators' attacks, like some aterinids. These fish have a bright
coloration with a horizontal stripe which should disorient the predator
attacking these fish in the shoal. The same fish which do not form
permanent shoals have bright blue-white or greenish masking coloration
(genus Chromis).
The behavioral features of planktonovore fishes depend on their
individual hunting strategy. Daytime shoaling fish like Chromis and
Dascyllus form small shoals near the reef edge close to a possible refuge and
feed on zooplankton brought by the current (Hobson and Chess 1978;
Hammer et al. 1988). On being attacked, the shoal instantly goes into
hiding. At night, the shoals disperse and the fish spend the night in their
individual lodgings. Aterinids (Haemulon striatum) form permanent large
shoals. They feed in the water column, escaping attacks by instant reaction
of the whole shoal. Some daytime planktonovores remain immobHe behind
their refuges and catch zooplankton preys which are driven by the currents
behind them. These are for example the congrid garden eels. These
snakelike fish live in holes. Exposing from their holes half of their body
length, they catch zooplankton from the waters passing by (Randall 1967).
Some planktonovores use ambushing tactics, stay masked near their holes or
on a branch of coral and by blitz-attack hurls catch their prey. Among them
there are some species of holocentrids, gobiids and cirrithids.
235
mulon, Eguetus acuminatus), Pomacentridae (Genus Chromis, Pomacentrus
coeletus, Amblygliphiodon curacao, Dascyllus reticulatus), Gobiidae (genera
Joglossus, Ptereleotris, Cottogobius), Chaetodontidae (Chaetodon sedentaris), Apogonidae (Apogon gracilis, A. novaeaquinea, A. savayensis, A.
binotatus), Holocentridae (Myripristis pralinus, M. jackobius, M. violaceus),
Cyrrithidae (Amblycirrithes pinos), and Congridae (Nystactichthys haila,
Gorgasia sillineri, Taeniconger halis). The families of reef planktonovorous
fish Atherinidae and Caesionidae descended from the perchiform fish. The
genera Aterina, Allanetta, Pranesus, Caesio and Pterocassio are among the
most common reef fish feeding on zooplankton (see Tables 6.8, 6.10,
6.13).
The morphological adaptations in the secondary planktonovores are
manifest largely in the changes of morphology of mouth parts. Their jaws
expanded and became tube-like. On opening, the mouth sucks water inside
as a pipette together with the zooplankters which the fish is hunting for.
Their teeth became tiny, the gills denser, the cranium bones thin, and the
eyes enlarged. The size of their body reduced and assumed a spindle-like
form. In some of these fish the morphological changes connected with
transition to plankton feeding were so deep, that they could easily be
accepted as representatives of another family, such as the serranid Schulzea
beta. There morphological changes were connected also with the transition
from single to schooling life, because within the schools the pressure of
grazing in the water column decreases (Davis and Birdsong 1973). With this,
too, is connected the coloration of the daytime planktonovores, which are
subjected to predators' attacks, like some aterinids. These fish have a bright
coloration with a horizontal stripe which should disorient the predator
attacking these fish in the shoal. The same fish which do not form
permanent shoals have bright blue-white or greenish masking coloration
(genus Chromis).
The behavioral features of planktonovore fishes depend on their
individual hunting strategy. Daytime shoaling fish like Chromis and
Dascyllus form small shoals near the reef edge close to a possible refuge and
feed on zooplankton brought by the current (Hobson and Chess 1978;
Hammer et al. 1988). On being attacked, the shoal instantly goes into
hiding. At night, the shoals disperse and the fish spend the night in their
individual lodgings. Aterinids (Haemulon striatum) form permanent large
shoals. They feed in the water column, escaping attacks by instant reaction
of the whole shoal. Some daytime planktonovores remain immobHe behind
their refuges and catch zooplankton preys which are driven by the currents
behind them. These are for example the congrid garden eels. These
snakelike fish live in holes. Exposing from their holes half of their body
length, they catch zooplankton from the waters passing by (Randall 1967).
Some planktonovores use ambushing tactics, stay masked near their holes or
on a branch of coral and by blitz-attack hurls catch their prey. Among them
there are some species of holocentrids, gobiids and cirrithids.