23 – Arthropoda: Crustaceans and Pycnogonids
269
penaeids ‘grow-out’ in estuaries or nearshore habitats,
and migrate offshore as adults, but red-spot king
prawns spend their entire lives in the vicinity of the
reef. Juveniles use shallow reef flats and lagoon areas
as a nursery, and adults move to deeper parts of the
lagoon to spawn.
Caridea: shrimps
The shrimps of the Infraorder Caridea, like the prawns,
are accomplished swimmers. Unlike prawns, however,
carideans incubate their eggs beneath the abdomen,
have only two pairs of chelipeds and have the pleuron
(lateral plate) of the second abdominal segment overlapping both those of the first and third segments. More
than 200 species of caridean shrimp are presently
known from the GBR, the most common of which are
members of the Palaemonidae (subfamily Pontoninae)
and Alpheidae. Most GBR pontonines are associates of
other reef invertebrates: corals, anemones, nudibranchs,
sponges, echinoderms and molluscs. Pontonines (Fig.
23.2I–L) tend to be delicate and retiring, and though
common, must be searched for. One of the more easily
found pontonines is Periclimenes brevicarpalis (Fig.
23.2L), which lives under the protection of the tentacles
of sea anemones. Here, P. brevicarpalis rolls and sways
its body, which is transparent except for its several
large white patches, and orange and purple highlights.
Interestingly, few pontonines have drab colouration;
most are either brightly coloured or almost completely
transparent. Alpheids, the snapping shrimps, are abundant throughout the GBR, but are more often heard
than seen. Snapping shrimps live in burrows in sand,
sponge, mud and coralline rock. The characteristic feature of the snapping shrimps is the greatly enlarged
snapping claw, which, when snapped shut produces a
loud, cracking sound with a localised shock wave sufficient to injure or kill small invertebrates and fish.
Snapping shrimps usually live in pairs, but some form
large social networks (e.g. Synalpheus; Fig. 23.2J), and
many species of Alpheus cooperatively share a burrow
with gobiid fish. Other conspicuous carideans on the
reef include the cleaner shrimp, Lysmata amboinensis,
the hinged-beak shrimps (Rhynchocinetes durbanensis;
Fig. 23.2K) and the marbled shrimp (Saron marmoratus).
One of the most unusual shrimps on the GBR is the
harlequin shrimp (Hymenocera picta), which feeds exclusively on seastars. As a rule, caridean shrimps hide
during the day and are best observed at night, when
they emerge to feed.
Stenopodidea: coral shrimps
The stenopodidean shrimps are generally small, spiny
shrimps characterised by having three pairs of chelipeds of which the third pair is the largest. Four species
of stenopodidean are known from the GBR of which
the red and white banded coral shrimp, Stenopus
hispidus (Fig. 23.3A), is the largest and most familiar,
reaching about 75 mm in length. Banded coral shrimps
live in mated pairs in deep, rock or coral crevices and
on the underside of overhangs. They are also known as
‘fish cleaners’. Pairs of S. hispidus attract fish to their
‘cleaning station’ by waving their long, white antennae. Large fish approach the cleaning station, where
the shrimps ‘pick-off’ dead skin and parasites. Other
stenopodideans on the GBR include other species of
Stenopus and the 15 mm Microprosthema validum.
Achelata: spiny and slipper lobsters
The spiny lobsters (Palinuridae) and slipper lobsters
(Scyllaridae) are unusual decapods in lacking chelipeds. They are common on the reef flat and slope where
they hide in crevices by day and emerge at night to
feed. Palinurids include the large, edible species like
the painted cray (Panulirus versicolor), ornate cray (P.
ornatus) and spotted cray (P. bispinosus (Fig. 23.3B), often misidentified as P. femoristraga), for which a commercial fishery operates in northern reef waters between
Cape York and Princess Charlotte Bay. Unlike their
temperate water counterparts, species of Panulirus seldom enter traps, and are instead harvested by hand.
Scyllarids are smaller than palinurids, and the antennae, rather than being long and whip-like, are formed
into short flat plates. Whereas tropical palinurids are
usually brightly coloured, scyllarids are often camouflaged to match their coralline surroundings. Scyllarids, such as Scyllarides and Parribacus, are common on
the reef slope, among coral and rubble, whereas Thenus
(Fig. 23.3C) and Ibacus, often called ‘bugs’, live on the
muddy inter-reef sediments where they are commercially trawled. An unusual feature of Thenus and Ibacus,
269
penaeids ‘grow-out’ in estuaries or nearshore habitats,
and migrate offshore as adults, but red-spot king
prawns spend their entire lives in the vicinity of the
reef. Juveniles use shallow reef flats and lagoon areas
as a nursery, and adults move to deeper parts of the
lagoon to spawn.
Caridea: shrimps
The shrimps of the Infraorder Caridea, like the prawns,
are accomplished swimmers. Unlike prawns, however,
carideans incubate their eggs beneath the abdomen,
have only two pairs of chelipeds and have the pleuron
(lateral plate) of the second abdominal segment overlapping both those of the first and third segments. More
than 200 species of caridean shrimp are presently
known from the GBR, the most common of which are
members of the Palaemonidae (subfamily Pontoninae)
and Alpheidae. Most GBR pontonines are associates of
other reef invertebrates: corals, anemones, nudibranchs,
sponges, echinoderms and molluscs. Pontonines (Fig.
23.2I–L) tend to be delicate and retiring, and though
common, must be searched for. One of the more easily
found pontonines is Periclimenes brevicarpalis (Fig.
23.2L), which lives under the protection of the tentacles
of sea anemones. Here, P. brevicarpalis rolls and sways
its body, which is transparent except for its several
large white patches, and orange and purple highlights.
Interestingly, few pontonines have drab colouration;
most are either brightly coloured or almost completely
transparent. Alpheids, the snapping shrimps, are abundant throughout the GBR, but are more often heard
than seen. Snapping shrimps live in burrows in sand,
sponge, mud and coralline rock. The characteristic feature of the snapping shrimps is the greatly enlarged
snapping claw, which, when snapped shut produces a
loud, cracking sound with a localised shock wave sufficient to injure or kill small invertebrates and fish.
Snapping shrimps usually live in pairs, but some form
large social networks (e.g. Synalpheus; Fig. 23.2J), and
many species of Alpheus cooperatively share a burrow
with gobiid fish. Other conspicuous carideans on the
reef include the cleaner shrimp, Lysmata amboinensis,
the hinged-beak shrimps (Rhynchocinetes durbanensis;
Fig. 23.2K) and the marbled shrimp (Saron marmoratus).
One of the most unusual shrimps on the GBR is the
harlequin shrimp (Hymenocera picta), which feeds exclusively on seastars. As a rule, caridean shrimps hide
during the day and are best observed at night, when
they emerge to feed.
Stenopodidea: coral shrimps
The stenopodidean shrimps are generally small, spiny
shrimps characterised by having three pairs of chelipeds of which the third pair is the largest. Four species
of stenopodidean are known from the GBR of which
the red and white banded coral shrimp, Stenopus
hispidus (Fig. 23.3A), is the largest and most familiar,
reaching about 75 mm in length. Banded coral shrimps
live in mated pairs in deep, rock or coral crevices and
on the underside of overhangs. They are also known as
‘fish cleaners’. Pairs of S. hispidus attract fish to their
‘cleaning station’ by waving their long, white antennae. Large fish approach the cleaning station, where
the shrimps ‘pick-off’ dead skin and parasites. Other
stenopodideans on the GBR include other species of
Stenopus and the 15 mm Microprosthema validum.
Achelata: spiny and slipper lobsters
The spiny lobsters (Palinuridae) and slipper lobsters
(Scyllaridae) are unusual decapods in lacking chelipeds. They are common on the reef flat and slope where
they hide in crevices by day and emerge at night to
feed. Palinurids include the large, edible species like
the painted cray (Panulirus versicolor), ornate cray (P.
ornatus) and spotted cray (P. bispinosus (Fig. 23.3B), often misidentified as P. femoristraga), for which a commercial fishery operates in northern reef waters between
Cape York and Princess Charlotte Bay. Unlike their
temperate water counterparts, species of Panulirus seldom enter traps, and are instead harvested by hand.
Scyllarids are smaller than palinurids, and the antennae, rather than being long and whip-like, are formed
into short flat plates. Whereas tropical palinurids are
usually brightly coloured, scyllarids are often camouflaged to match their coralline surroundings. Scyllarids, such as Scyllarides and Parribacus, are common on
the reef slope, among coral and rubble, whereas Thenus
(Fig. 23.3C) and Ibacus, often called ‘bugs’, live on the
muddy inter-reef sediments where they are commercially trawled. An unusual feature of Thenus and Ibacus,