164
Reef Zoobenthos
1984). These predatory gastropods, as well as the species of the related
families of Tonniqae, Magilidae, Buccinidae and Vasidae, feed mainly on
other moluscs and on polychaetes. Muricids bore small holes in the shells of
their molluscan prey with the aid of acid secreted by a special gland.
Among the families of predatory gastropods listed above several trophic
guilds could be differentiated (Reichelt and Kohn 1985). The largest of them
are gastropods feeding exclusively on the errant polychaetes eunicids and
spionids. On the reef-flat biotope of the Guam reefs this guilds included 16
species of gastropods from the genera Conus, Drupa, Cantharus, Engina,
Vasum, Iredalea, Bursa. The second guild is formed by predatory gastropods
feeding mainly on meyo- and micro benthic omnivorous gastropods, such as
Bittum, Dendropoma, and Diala. This guild includes species from the
families Muricidae, Thaisidae and Costellariidae (Pusia sp.). Pusia paralyses
its preys by covering them with the poisonous mucus. The third guild
comprises the gastropods Mitra litterata, M. cucumerina, Imbricularia
conovula (fam. Mitridae), Drupa grossularia (fam. Thaisidae) and Vasum
turbinellus. They feed mainly on sipunculid worms. Some of the predatory
gastropods feed on sea urchins (Bursa bufonia), asteroids (Charonia tritonis
and some of the Cymatiidae fam.), on small benthic crustaceans (Drupa
ricinus, Cantharus fumosum). Among them there are also species with a
wide food spectrum, like some species of the genera Cantharus, Vasum,
Nassarins, Bursa, and Conus. Conids feed also on the eggs of benthic
invertebrates and on corpses. Several species of predatory gastropods are
living in associations with the scleractinians, octocorals and zoantharians,
and feed on them. The corallovorous gastropods have toothed firm radula to
scrape out the tissues from the surface of coral colonies. The Heliacus sp.
have a proboscis, which ends in a mouth armed with the same kind of
radula.
The corallovorous gastropods graze the mucus and the zooxanthellae, as
well as the polyps. The prosobranches prefer the scleractinian hard corals,
while the opistobranchs feed mostly on soft corals - alcyonaceans and
gorgonaceans. The corallovorous prosobranchs belong mainly to the families
Architectonidae (Philippia radiata), Epitonidae (Epitonium ulu), Magilidae
(genera Corallophyla, Quoyula, Leptoconchus, Magi/opsis, Magilus), Thaisidae (Drupa comus, Drupella fragum) , Ovulidae (Jenneria pustulata,
Pedicularia decussata). Some Magilids (Corallophyla) are feeding on anipatharian corals. Corallophyla sp. and some architectonids (Heliactis) live in
association with zoantharians, escaping their nematocysts, and feed on their
mucus and on zooxanthellae. The Heliactis sp. graze also their polyps
(Robertson 1980). In some corallovorous genera a fine trophic specialization
was recorded. For example, Corallophyla violacea feeds only on the coral
Porites, C. erosa and C. deformis on acroporid corals, C. abbreviata on
Montipora, C. monodonta on gorgonaceans and on zoantharians, Quoyula
madreporatium prefers the coral Pocillopora, Q. monodonta the corals
Stylophora and Seriatopora, Leptoconchus cumingi the coral Goniopora
Reef Zoobenthos
1984). These predatory gastropods, as well as the species of the related
families of Tonniqae, Magilidae, Buccinidae and Vasidae, feed mainly on
other moluscs and on polychaetes. Muricids bore small holes in the shells of
their molluscan prey with the aid of acid secreted by a special gland.
Among the families of predatory gastropods listed above several trophic
guilds could be differentiated (Reichelt and Kohn 1985). The largest of them
are gastropods feeding exclusively on the errant polychaetes eunicids and
spionids. On the reef-flat biotope of the Guam reefs this guilds included 16
species of gastropods from the genera Conus, Drupa, Cantharus, Engina,
Vasum, Iredalea, Bursa. The second guild is formed by predatory gastropods
feeding mainly on meyo- and micro benthic omnivorous gastropods, such as
Bittum, Dendropoma, and Diala. This guild includes species from the
families Muricidae, Thaisidae and Costellariidae (Pusia sp.). Pusia paralyses
its preys by covering them with the poisonous mucus. The third guild
comprises the gastropods Mitra litterata, M. cucumerina, Imbricularia
conovula (fam. Mitridae), Drupa grossularia (fam. Thaisidae) and Vasum
turbinellus. They feed mainly on sipunculid worms. Some of the predatory
gastropods feed on sea urchins (Bursa bufonia), asteroids (Charonia tritonis
and some of the Cymatiidae fam.), on small benthic crustaceans (Drupa
ricinus, Cantharus fumosum). Among them there are also species with a
wide food spectrum, like some species of the genera Cantharus, Vasum,
Nassarins, Bursa, and Conus. Conids feed also on the eggs of benthic
invertebrates and on corpses. Several species of predatory gastropods are
living in associations with the scleractinians, octocorals and zoantharians,
and feed on them. The corallovorous gastropods have toothed firm radula to
scrape out the tissues from the surface of coral colonies. The Heliacus sp.
have a proboscis, which ends in a mouth armed with the same kind of
radula.
The corallovorous gastropods graze the mucus and the zooxanthellae, as
well as the polyps. The prosobranches prefer the scleractinian hard corals,
while the opistobranchs feed mostly on soft corals - alcyonaceans and
gorgonaceans. The corallovorous prosobranchs belong mainly to the families
Architectonidae (Philippia radiata), Epitonidae (Epitonium ulu), Magilidae
(genera Corallophyla, Quoyula, Leptoconchus, Magi/opsis, Magilus), Thaisidae (Drupa comus, Drupella fragum) , Ovulidae (Jenneria pustulata,
Pedicularia decussata). Some Magilids (Corallophyla) are feeding on anipatharian corals. Corallophyla sp. and some architectonids (Heliactis) live in
association with zoantharians, escaping their nematocysts, and feed on their
mucus and on zooxanthellae. The Heliactis sp. graze also their polyps
(Robertson 1980). In some corallovorous genera a fine trophic specialization
was recorded. For example, Corallophyla violacea feeds only on the coral
Porites, C. erosa and C. deformis on acroporid corals, C. abbreviata on
Montipora, C. monodonta on gorgonaceans and on zoantharians, Quoyula
madreporatium prefers the coral Pocillopora, Q. monodonta the corals
Stylophora and Seriatopora, Leptoconchus cumingi the coral Goniopora