Tunicates
201
Stychopidae and Synaptidae. The common species of holothuriids are
Holothuria atra, H. leucospilota, H. edulis, H. arenicola, H. argus, H.
dificilis, H. scabra, H. hilla, H. albiventer, H. coluber, Halodeima atra, H.
edulis, Actinopyga echinites, A. mauritania, A. miliaris, Bohadschia argus,
and B. marmorata. The common stychopids are: Stychopus chloronotus, S.
variegatus, and Thelenota ananas. The common synaptids are: Euapta lappa,
Synapta maculata, and Synaptula recta. In soft silty sands live, buried in the
sediment, the sedentary holothurians Cucumaria and Pentacta from the
family Dendrotrichidae. The animals thrust their contractible mobile mouth
tentacles out and so collect food material from the bottom surface.
Holothurians are scantily grazed on reefs because they are protected by
their firm tunics, and many of them are poisonous for fish. Some
holothurians, like Actynopiga parvula and Holothuria difficilis, on being
endangered throw out culverian threads - poisonous sticky filaments, which
immobilize the attacker (Bakus 1968, 1973). Therefore, their main predators
on reefs are people. Their dry tunics (trepang) are sold as a delicacy on the
markets of S.E. Asia and Oceania (Bakus 1973; Con and 1981). The mainly
fished holothurians belong to the genera: Holothuria, Thelenota, Microthele,
and Actinopiga. The production of two edible species of holothurians,
Holothuria atra and Actynopiga echinites, at reef shallows off New
Caledonia was estimated to be about 1 t/ha, or about 40 kg of dry meat
(trepang). They grow rather fast: the linear increase is 5-10 mm, and the
weight increase 15-25 g by month.
5.6 Tunicates
The sedentary tunicates, solitary or colonial ascidians, are an important
component of the reef criptofauna. They live mostly in trenches, under
stones or in dead corals. Their bodies - zooids - are hidden inside the firm
test or tunic. It consists of tunicin - a firm material composed by the
polysaccharide fibers compacted by structuring proteins and a mass of tiny
carbonate spicules. In some of their colonial species many zooids are hidden
inside one big common test. They are represented by the families Polyclinidae, Polyclitoridae, Corallidae, Botrillinidae, Didemnidae. In colonial
ascidians united within the families Scavelinidae and Perphoridae. zooids are
joined within the common test by stolones only at its base. The colonial
ascidians often form incrusting flat colonies which like skin spread over
dead coral heads, up the walls of trenches, or fill spaces under stones. The
solitary reef ascidians, which belong mostly to the families Ascidiidae,
Diazonidae, Styelidae, and Pynridae, also prefer cryptic habitats, while
some of their spectacularly large species could be seen also in daylight on
the surface of reef rocks.
201
Stychopidae and Synaptidae. The common species of holothuriids are
Holothuria atra, H. leucospilota, H. edulis, H. arenicola, H. argus, H.
dificilis, H. scabra, H. hilla, H. albiventer, H. coluber, Halodeima atra, H.
edulis, Actinopyga echinites, A. mauritania, A. miliaris, Bohadschia argus,
and B. marmorata. The common stychopids are: Stychopus chloronotus, S.
variegatus, and Thelenota ananas. The common synaptids are: Euapta lappa,
Synapta maculata, and Synaptula recta. In soft silty sands live, buried in the
sediment, the sedentary holothurians Cucumaria and Pentacta from the
family Dendrotrichidae. The animals thrust their contractible mobile mouth
tentacles out and so collect food material from the bottom surface.
Holothurians are scantily grazed on reefs because they are protected by
their firm tunics, and many of them are poisonous for fish. Some
holothurians, like Actynopiga parvula and Holothuria difficilis, on being
endangered throw out culverian threads - poisonous sticky filaments, which
immobilize the attacker (Bakus 1968, 1973). Therefore, their main predators
on reefs are people. Their dry tunics (trepang) are sold as a delicacy on the
markets of S.E. Asia and Oceania (Bakus 1973; Con and 1981). The mainly
fished holothurians belong to the genera: Holothuria, Thelenota, Microthele,
and Actinopiga. The production of two edible species of holothurians,
Holothuria atra and Actynopiga echinites, at reef shallows off New
Caledonia was estimated to be about 1 t/ha, or about 40 kg of dry meat
(trepang). They grow rather fast: the linear increase is 5-10 mm, and the
weight increase 15-25 g by month.
5.6 Tunicates
The sedentary tunicates, solitary or colonial ascidians, are an important
component of the reef criptofauna. They live mostly in trenches, under
stones or in dead corals. Their bodies - zooids - are hidden inside the firm
test or tunic. It consists of tunicin - a firm material composed by the
polysaccharide fibers compacted by structuring proteins and a mass of tiny
carbonate spicules. In some of their colonial species many zooids are hidden
inside one big common test. They are represented by the families Polyclinidae, Polyclitoridae, Corallidae, Botrillinidae, Didemnidae. In colonial
ascidians united within the families Scavelinidae and Perphoridae. zooids are
joined within the common test by stolones only at its base. The colonial
ascidians often form incrusting flat colonies which like skin spread over
dead coral heads, up the walls of trenches, or fill spaces under stones. The
solitary reef ascidians, which belong mostly to the families Ascidiidae,
Diazonidae, Styelidae, and Pynridae, also prefer cryptic habitats, while
some of their spectacularly large species could be seen also in daylight on
the surface of reef rocks.