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Reef Zoobenthos
1974). The number of species of these stars varies within a particular reef
system between 5 and 60. Their total number on reefs of the Indo-Pacific is
close to 300, and in the Western Atlantic to 50 (Devaney 1974; Clark 1976;
Hotchkiss 1982; Marsh and Marshall 1983). The brittle stars have five
snake-like long slender flexible arms - tentacles lined with long ambulacral
tube feet. These ambulacral feet secretes mucus and, being extremely
motile, can catch particles suspended in the water column. Most brittle stars
are sedimentary and filter-feeders, and can also collect detritus and dead
plankton from the bottom surface. Thus they feed on plankton and
hyponeuston, on detritus, and also catch small benthic animals. Their
different genera have various trophic orientations. Some are pure filterers,
like Ophiothrix and Ophiopholis (Roushdy and Hansen 1960). Some are
feeding on hyponeustonic plankton living in the surface film, like
Ophiocoma scolopendrina. These brittle stars live in trenches on the reef
flat. When the tide is rising they anchor themselves with the aid of 1 or 2
tentacles onto the surface of flats. Another tentacle they stretch out to meet
the tide current and collect detritus and plankton from the water surface.
The filtering stars come out from their shelters at night and after anchoring
themselves to the bottom form with their tentacles a kind of fan across the
passing current, catching phytoplankton, detritus and small zooplankters
(Woodley 1975). The food particles thus collected are transported along
the ambulacral channel of the tentacles to the mouth (Magnus 1967;
Meyer 1973a; Kissling and Taylor 1977). Some species of stars cannot
filter at all, for being specialized to collect food from solid surfaces
(Ophiocomina) .
Common reef brittle stars are: Ophiocoma, Ophiocomelia, Ophiomastix
(family Ophiocomidae), Ophiothrix, Macrophiothrix, Ophiactis (fam.
Ophiothrichidae), Ophiarachna, Ophiopholis, Ophiopeza (fam. Ophiodermatidae), Ophionereis (fam. Ophionereidae), Amphiura, Amphipholis
(fam. Amphipholidae), Ophiura, Ophiolepis (fam. Ophiuridae). The
trophic specialization of different species of ophiuroids makes for a zonal
distribution of their taxa in reef biotopes (Meyer 1973b; Devaney 1974).
Thus, on the reefs of Florida on the soft bottom overgrown with seagrass
and weeds the detritovorous species Ophiothrix erstedi and O. sabrisculata
were the most numerous. On the reef-flat Ophiocoma appresum, O.
echinata, and O. phiollpis impressa were the most usual. Near the reef
edge filtering stars were common: Ophiocoma pumila, O. echinata, and
O. wendtii. In biotopes of the outer slope Ophionereis reti.culata and in
the fore-reef zone Ophiozona impressa and Ophiothrix lineata dominated
(Kissling and Taylor 1977; Hotchkiss 1982). Some small ophiuroids live as
commensals within the colonies of corals (Ophiothela tigris) or within the
sponges (Ophiocomella sp.; Clark 1976). The largest number of brittle stars30 sp. m- 2 - was recorded in the rubble biotope of an Atlantic reef (Bray
1981). Brittle stars playa quite noticeable role in reef trophodynamics,
forming an important component of its biofilter.
Reef Zoobenthos
1974). The number of species of these stars varies within a particular reef
system between 5 and 60. Their total number on reefs of the Indo-Pacific is
close to 300, and in the Western Atlantic to 50 (Devaney 1974; Clark 1976;
Hotchkiss 1982; Marsh and Marshall 1983). The brittle stars have five
snake-like long slender flexible arms - tentacles lined with long ambulacral
tube feet. These ambulacral feet secretes mucus and, being extremely
motile, can catch particles suspended in the water column. Most brittle stars
are sedimentary and filter-feeders, and can also collect detritus and dead
plankton from the bottom surface. Thus they feed on plankton and
hyponeuston, on detritus, and also catch small benthic animals. Their
different genera have various trophic orientations. Some are pure filterers,
like Ophiothrix and Ophiopholis (Roushdy and Hansen 1960). Some are
feeding on hyponeustonic plankton living in the surface film, like
Ophiocoma scolopendrina. These brittle stars live in trenches on the reef
flat. When the tide is rising they anchor themselves with the aid of 1 or 2
tentacles onto the surface of flats. Another tentacle they stretch out to meet
the tide current and collect detritus and plankton from the water surface.
The filtering stars come out from their shelters at night and after anchoring
themselves to the bottom form with their tentacles a kind of fan across the
passing current, catching phytoplankton, detritus and small zooplankters
(Woodley 1975). The food particles thus collected are transported along
the ambulacral channel of the tentacles to the mouth (Magnus 1967;
Meyer 1973a; Kissling and Taylor 1977). Some species of stars cannot
filter at all, for being specialized to collect food from solid surfaces
(Ophiocomina) .
Common reef brittle stars are: Ophiocoma, Ophiocomelia, Ophiomastix
(family Ophiocomidae), Ophiothrix, Macrophiothrix, Ophiactis (fam.
Ophiothrichidae), Ophiarachna, Ophiopholis, Ophiopeza (fam. Ophiodermatidae), Ophionereis (fam. Ophionereidae), Amphiura, Amphipholis
(fam. Amphipholidae), Ophiura, Ophiolepis (fam. Ophiuridae). The
trophic specialization of different species of ophiuroids makes for a zonal
distribution of their taxa in reef biotopes (Meyer 1973b; Devaney 1974).
Thus, on the reefs of Florida on the soft bottom overgrown with seagrass
and weeds the detritovorous species Ophiothrix erstedi and O. sabrisculata
were the most numerous. On the reef-flat Ophiocoma appresum, O.
echinata, and O. phiollpis impressa were the most usual. Near the reef
edge filtering stars were common: Ophiocoma pumila, O. echinata, and
O. wendtii. In biotopes of the outer slope Ophionereis reti.culata and in
the fore-reef zone Ophiozona impressa and Ophiothrix lineata dominated
(Kissling and Taylor 1977; Hotchkiss 1982). Some small ophiuroids live as
commensals within the colonies of corals (Ophiothela tigris) or within the
sponges (Ophiocomella sp.; Clark 1976). The largest number of brittle stars30 sp. m- 2 - was recorded in the rubble biotope of an Atlantic reef (Bray
1981). Brittle stars playa quite noticeable role in reef trophodynamics,
forming an important component of its biofilter.