80
R. K. DELL
breeding biology at the South Orkneys. The species has also been
mentioned in describing associations of animals from relatively shallow
water, e.g. Price and Redfearn (1968) at the South Orkneys, McCain and
Stout (1969) on the Antarctic Peninsula and Gruzov and Pushkin (1970)
in the South Shetlmds. I n McMurdo Sound, Glyptonotus lives on wide
range of substrates in depths down to at least 585 m. Specimens collected by Dearborn ranged from 51 to 111 mm in total length, a giant
amongst isopods. The gut contents, examined in 118 adults, revealed a
wide range of food. The commonest occurring foods were ophiuroids
(52.3%), gastropods (19.3%), isopods (17.4%) and echinoids (14.7%).
Of the prey identified to species the following are noteworthy : Ophiacanthu antarctica Koehler and Ophiurolepis gelida (Koehler) (the two
commonest brittle stars in the area), Margarella refulgens (Smith) (a
very common small trochoid gastropod), Glyptonotus, Sterechinus
neumayeri (Meissner) (an echinoid) and Anthometra adriani (Bell) (one
of the two common crinoids). Other groups represented were bivalves
polychaetes, pycnogonids, sponges, brachiopods and algae.
Many of the specimens were collected in baited traps so that the
presence of seal meat and fish used as bait is to be expected but does
indicate that this species may be necrophagous. Many of the specimens
also contained the amphipod Orchomenella, but since this species is also
attracted to bait in enormous numbers its apparent importance as food
for Glyptonotus may have been artificially induced by the trapping
technique. From an analysis of the gut contents of specimens taken
from different substrates Dearborn concludes that availability of food
is more important than the type of prey. This seems another successful
Antarctic species which has a wide range of foods.
Interesting adaptations are the modifications of the three anterior
pairs of legs to form prehensile organs, the large powerful mouthparts,
and divided thoracic somites which allow for great expansion to accommodate large quantities of food. The species can swim actively with
the ventral surface uppermost.
Dearborn concludes that the ecological role of Clyptonotus is ‘‘ as
a large predator and scavenger on the bottom ” perhaps taking the place
of crabs and lobsters in the temperate benthos.
Dearborn found little evidence that Glyptonotus was preyed upon by
other animals, except that small examples were eaten by the common
bottom fish, Trematomus bernacchii Boulenger.
Once males reach maturity they grasp an immature female and the
pairs remain associated. White recorded periods of attachment up to
190 days. During this period males may change females from time to
time, but the pair bond seems much more binding for the 30 days or so
R. K. DELL
breeding biology at the South Orkneys. The species has also been
mentioned in describing associations of animals from relatively shallow
water, e.g. Price and Redfearn (1968) at the South Orkneys, McCain and
Stout (1969) on the Antarctic Peninsula and Gruzov and Pushkin (1970)
in the South Shetlmds. I n McMurdo Sound, Glyptonotus lives on wide
range of substrates in depths down to at least 585 m. Specimens collected by Dearborn ranged from 51 to 111 mm in total length, a giant
amongst isopods. The gut contents, examined in 118 adults, revealed a
wide range of food. The commonest occurring foods were ophiuroids
(52.3%), gastropods (19.3%), isopods (17.4%) and echinoids (14.7%).
Of the prey identified to species the following are noteworthy : Ophiacanthu antarctica Koehler and Ophiurolepis gelida (Koehler) (the two
commonest brittle stars in the area), Margarella refulgens (Smith) (a
very common small trochoid gastropod), Glyptonotus, Sterechinus
neumayeri (Meissner) (an echinoid) and Anthometra adriani (Bell) (one
of the two common crinoids). Other groups represented were bivalves
polychaetes, pycnogonids, sponges, brachiopods and algae.
Many of the specimens were collected in baited traps so that the
presence of seal meat and fish used as bait is to be expected but does
indicate that this species may be necrophagous. Many of the specimens
also contained the amphipod Orchomenella, but since this species is also
attracted to bait in enormous numbers its apparent importance as food
for Glyptonotus may have been artificially induced by the trapping
technique. From an analysis of the gut contents of specimens taken
from different substrates Dearborn concludes that availability of food
is more important than the type of prey. This seems another successful
Antarctic species which has a wide range of foods.
Interesting adaptations are the modifications of the three anterior
pairs of legs to form prehensile organs, the large powerful mouthparts,
and divided thoracic somites which allow for great expansion to accommodate large quantities of food. The species can swim actively with
the ventral surface uppermost.
Dearborn concludes that the ecological role of Clyptonotus is ‘‘ as
a large predator and scavenger on the bottom ” perhaps taking the place
of crabs and lobsters in the temperate benthos.
Dearborn found little evidence that Glyptonotus was preyed upon by
other animals, except that small examples were eaten by the common
bottom fish, Trematomus bernacchii Boulenger.
Once males reach maturity they grasp an immature female and the
pairs remain associated. White recorded periods of attachment up to
190 days. During this period males may change females from time to
time, but the pair bond seems much more binding for the 30 days or so