Wormlike Animals
187
The polychaetes use various sources of food available in reef biotopes and
build up a significant biomass of a high trophical quality. Thus they play a
very important role in the trophodynamics of coral reef ecosystems. They
are a significant source of food for most reef fish feeding on zoo benthos and
for the predatory invertebrates, especially molluscs, as well as for many
planktonovorous fish (Kohn 1968; Bakus 1969; Vittor and Johnson 1977).
Having a small average body size and a high growth rate and being able
(syllids) to mUltiply vegetatively, the polychaetes compose a great part, or
sometimes even the main portion, of the total production of reef zoobenthos
(Hutchings 1974, 1981).
Besides the polychaetes as significant components of the reef zoobenthos,
there are also other groups of worms - the sipunculids and the nematods. In
some bottom biopopes the benthic fauna includes also the echiurids, the
oligochaetes and the turbellarians. But the density of their populations is
usually low.
The sipunculid and the echiurid worms are now recognized as a separate
phyla of invertebrates. The sipunculids have a short sack- or cylinder-like
nonsegmented body. Their size varies from 2mm to 1Ocm. At the end of the
body they have a trunk. The mouth is situated at the end of the trunk. It is
armed with horny teeth and is surrounded with a row of tentacles. They dig
out holes in sediments or bore into the rocky substrates, being so an important component of the reef-boring fauna (Warme 1977; Peyrot-Clausade
et al. 1989). The density of populations of these worms in reef-flat biotopes
can be significant - up to 1-2 X 10 3 sp. m- 2 with a biomass up to 2030gm- 2 . In soft bottom areas it is less: 20-50 sp. m- 2 (Rice and Macintyre
1982). Their communities on individual reefs include 5 to 30 species. In
total, the fauna of the coral reef sipunculids lists about 300 species (Rice
1976). In the flat rocks the most numerous are the boring sipunculids, like
Paraspidosiphon, Aspidosiphon, Lithacrosiphon, Siphonosoma. The worm
Aspidosiphon elegante bores into the living corals, and A. jukesi lives in
symbiosis with the solitary coral Heterocyathus (cf. Sect. 7.3). In soft
sediments in holes live Siphonosoma novaepommeraniae, S. vasum, Phascolosoma perlucens, Golfingia misakiana.
The echiurids externally resemble the sipunculids. They live in holes, in
trenches, under the stones. With the aid of their trunks similar to those of
the sipunculids, they collect the detritus. The most common genera of the
reef echiurids are: Anelassorhynchus, Pseudolonellia, and Achaetobonellia.
The reef annelid worms oligochaetes are represented in reef bottom
biotopes mainly by the tubificids and to a lesser degree by the enchitreids.
Their size is 5-20 mm. Some of the tubificid oligochaetes (Phillodrilus,
Corallodrilus) have no intestines but have symbiotic bacteria in their bodies.
Most of them feed on bacteria and on fine detritus. Besides the abovementioned genera of tubificids Limnodriloides, Heterodriloides, Marcusaedrilus are often present in the reef meyobenthos (Jamieson 1977; Mather
and Bennett 1984). They occur in relatively small quantities in the meyo-
187
The polychaetes use various sources of food available in reef biotopes and
build up a significant biomass of a high trophical quality. Thus they play a
very important role in the trophodynamics of coral reef ecosystems. They
are a significant source of food for most reef fish feeding on zoo benthos and
for the predatory invertebrates, especially molluscs, as well as for many
planktonovorous fish (Kohn 1968; Bakus 1969; Vittor and Johnson 1977).
Having a small average body size and a high growth rate and being able
(syllids) to mUltiply vegetatively, the polychaetes compose a great part, or
sometimes even the main portion, of the total production of reef zoobenthos
(Hutchings 1974, 1981).
Besides the polychaetes as significant components of the reef zoobenthos,
there are also other groups of worms - the sipunculids and the nematods. In
some bottom biopopes the benthic fauna includes also the echiurids, the
oligochaetes and the turbellarians. But the density of their populations is
usually low.
The sipunculid and the echiurid worms are now recognized as a separate
phyla of invertebrates. The sipunculids have a short sack- or cylinder-like
nonsegmented body. Their size varies from 2mm to 1Ocm. At the end of the
body they have a trunk. The mouth is situated at the end of the trunk. It is
armed with horny teeth and is surrounded with a row of tentacles. They dig
out holes in sediments or bore into the rocky substrates, being so an important component of the reef-boring fauna (Warme 1977; Peyrot-Clausade
et al. 1989). The density of populations of these worms in reef-flat biotopes
can be significant - up to 1-2 X 10 3 sp. m- 2 with a biomass up to 2030gm- 2 . In soft bottom areas it is less: 20-50 sp. m- 2 (Rice and Macintyre
1982). Their communities on individual reefs include 5 to 30 species. In
total, the fauna of the coral reef sipunculids lists about 300 species (Rice
1976). In the flat rocks the most numerous are the boring sipunculids, like
Paraspidosiphon, Aspidosiphon, Lithacrosiphon, Siphonosoma. The worm
Aspidosiphon elegante bores into the living corals, and A. jukesi lives in
symbiosis with the solitary coral Heterocyathus (cf. Sect. 7.3). In soft
sediments in holes live Siphonosoma novaepommeraniae, S. vasum, Phascolosoma perlucens, Golfingia misakiana.
The echiurids externally resemble the sipunculids. They live in holes, in
trenches, under the stones. With the aid of their trunks similar to those of
the sipunculids, they collect the detritus. The most common genera of the
reef echiurids are: Anelassorhynchus, Pseudolonellia, and Achaetobonellia.
The reef annelid worms oligochaetes are represented in reef bottom
biotopes mainly by the tubificids and to a lesser degree by the enchitreids.
Their size is 5-20 mm. Some of the tubificid oligochaetes (Phillodrilus,
Corallodrilus) have no intestines but have symbiotic bacteria in their bodies.
Most of them feed on bacteria and on fine detritus. Besides the abovementioned genera of tubificids Limnodriloides, Heterodriloides, Marcusaedrilus are often present in the reef meyobenthos (Jamieson 1977; Mather
and Bennett 1984). They occur in relatively small quantities in the meyo-