Wormlike Animals
181
in bioerosion they may also act as reef builders. When they develop
vigorously within the masses of coral rubble in zones of moat and reef-flat
depressions, they cement separate pieces of rubble into one larger
aggregation attached to the rocky bottom by the same sponges. These
aggregations will be then consolidated by the coralline algae and become
solid lime rock, thus enhancing reef growth (Wulff 1984).
5.3 Wormlike Animals
The communities of polychaete worms on coral reefs are formed by two of
their suborders: the free-living errant polychaetes Errantia and the
sedentary polychaetes Sedentaria. The errant polychaetes have flat or round
bodies with rows of parapodia and cirrae on their sides. Their size varies
from 2 mm to 10 cm. The different taxa of Errantia, being trophically
specialized, their mouth apparatus is of a specific structure (Fauchald and
Jumars 1979). The sedentary polychaetes live in permanent or in temporal
tube homes. Their mouth parts are transformed into a filtering organ. They
feed on plankton and on suspended organic detritus.
The errant polychaetes, which inhabit reefs, belong to the following main
families: Nereidae, Eunicidae, Syllidae, Polynoidae, and Amphinomidae.
Less common families are: Cirratulidae, Aphroditidae, Glyceridae,
Phillodocidae. The nereids are relatively large omnivorous worms. They
have a flattened body with well-developed parapodia. They collect or
capture their food with the aid of an outstreched pharynx and with their
massive strong jaws. They prefer soft-bottom biotopes, where they build
their holes, compacted inside with the aid of mucus which they are
excreting. When feeding, the worm crawls out of its hole and collects all
food material around it: algae, detritus, small benthic animals. After that it
leaves the "home" and quickly builds a new one. Some species of nereids
are even filterers (Nereis diversicolor). They construst the mucus nets inside
their homes and pump water through it the same as chironomids do. Among
them there are also pure predators (N. grubel) and phytophages (N.
procera). But a main portion of the nereid species is omnivorous. Some
nereids change the form of their body during the mating period. Their
parapodia expand and on their heads big eyes appear. These worms in their
"wedding dress" are called heteronereids. After this metamorphosis they
ascend from bottom to water column. There the males and the females
perform the wedding dance, and afterward shed their eggs and sperm into
the water, where the fertilization takes place. This period is a feast for fish
(and for people too), they graze or catch a larger portion of the "dancing"
polychaetes. The mass species of the nereids are: Nereis caudata, N.
jalcaria, N. jacksoni, N. trijasciata, Platynereis isocita, Perinereis calodonta,
P. anomala, Ceratonereis mirabilis.
181
in bioerosion they may also act as reef builders. When they develop
vigorously within the masses of coral rubble in zones of moat and reef-flat
depressions, they cement separate pieces of rubble into one larger
aggregation attached to the rocky bottom by the same sponges. These
aggregations will be then consolidated by the coralline algae and become
solid lime rock, thus enhancing reef growth (Wulff 1984).
5.3 Wormlike Animals
The communities of polychaete worms on coral reefs are formed by two of
their suborders: the free-living errant polychaetes Errantia and the
sedentary polychaetes Sedentaria. The errant polychaetes have flat or round
bodies with rows of parapodia and cirrae on their sides. Their size varies
from 2 mm to 10 cm. The different taxa of Errantia, being trophically
specialized, their mouth apparatus is of a specific structure (Fauchald and
Jumars 1979). The sedentary polychaetes live in permanent or in temporal
tube homes. Their mouth parts are transformed into a filtering organ. They
feed on plankton and on suspended organic detritus.
The errant polychaetes, which inhabit reefs, belong to the following main
families: Nereidae, Eunicidae, Syllidae, Polynoidae, and Amphinomidae.
Less common families are: Cirratulidae, Aphroditidae, Glyceridae,
Phillodocidae. The nereids are relatively large omnivorous worms. They
have a flattened body with well-developed parapodia. They collect or
capture their food with the aid of an outstreched pharynx and with their
massive strong jaws. They prefer soft-bottom biotopes, where they build
their holes, compacted inside with the aid of mucus which they are
excreting. When feeding, the worm crawls out of its hole and collects all
food material around it: algae, detritus, small benthic animals. After that it
leaves the "home" and quickly builds a new one. Some species of nereids
are even filterers (Nereis diversicolor). They construst the mucus nets inside
their homes and pump water through it the same as chironomids do. Among
them there are also pure predators (N. grubel) and phytophages (N.
procera). But a main portion of the nereid species is omnivorous. Some
nereids change the form of their body during the mating period. Their
parapodia expand and on their heads big eyes appear. These worms in their
"wedding dress" are called heteronereids. After this metamorphosis they
ascend from bottom to water column. There the males and the females
perform the wedding dance, and afterward shed their eggs and sperm into
the water, where the fertilization takes place. This period is a feast for fish
(and for people too), they graze or catch a larger portion of the "dancing"
polychaetes. The mass species of the nereids are: Nereis caudata, N.
jalcaria, N. jacksoni, N. trijasciata, Platynereis isocita, Perinereis calodonta,
P. anomala, Ceratonereis mirabilis.