ANTARUTIC BENTHOS
63
direct evidence available now for the Antarctic benthos to be able to
state that it is exactly the groups listed above which are so highly
characteristic of many shelf areas.
The main Antarctic families not dealt with by Fry and Hedgpeth
(1969) are the families Nymphonidae and Pallenidae. The main
Antarctic genus of the family Nymphonidae is the genus Nymphon and
Gordon (1932) who attempted a revision has indicated some of the
difEoulties encountered in dealing with this group systematically. Dr
Gordon, herself, has indicated that her conclusions are tentative. She
keys some 31 Antarctic and Subantarctic species of the genus, which
would appear to be another good example of radiative evolution amongst
Antarctic animals.
Fry (1965) was able to study two live Antarctic species at McMurdo
Sound, Austrodecus glaciale and Rhynchothorax australis Hodgson. He
was particularly concerned with the food preferences of these two species,
which occurred in comparable numbers in approximately 280 m.
Specimens of Rhynchothorax were observed to ingest polyps of the
hydroid Eudendrium tottoni Stechow and in experimental work associated itself with this hydroid in preference to all other potential foods
offered. Austrodecus showed a marked preference for association with
the polyzoan Cellarinella foveolata Waters. Fry was able to show that
the h e pointed proboscis of Austrodecus glaciale would allow it to
probe through the frontal wall pores of the zooecium and so gain access
to the coelom of the polypides of Cellarinella. Austrodecus also requires
a leg span of about 10 mm or more to provide a 6rm platform for feeding. Only Cellarinella of the available polyzoans had frontal wall pores
large enough to allow the proboscis of A. glaciale to penetrate, in addition to supplying a broad, firm colony.
The Discovery collections included males of 16 species carrying eggs
or larvae. The dates of collection were from October to April (more
concentrated from December to March). In the Magellan area all such
males were collected in July (Gordon, 1932).
Many Antarctic pycnogonids have been collected encrusted with
other organisms. Gordon (1932) records mainly Polyzoa, Foraminifera
and hydroids, and occasionally brachiopods, sponges, tunicates and
serpulids. Occasional isopods have also been recorded clinging to
pycnogonids. Decolopoda antarctica is usually much more heavily
encrusted than D. australis, evidence presumably that D. antarctica is
a fairly sluggish animal.
Hedgpeth (1964, p. 45) has recorded the eggs of a prosobranch
attached to the legs of Antarctic pycnogonids from Eltanin Stations 410
(61"18'5, 56"08'3O''W, 120-131 fm) and 437 (62'49'36"S, 60"40'W,
63
direct evidence available now for the Antarctic benthos to be able to
state that it is exactly the groups listed above which are so highly
characteristic of many shelf areas.
The main Antarctic families not dealt with by Fry and Hedgpeth
(1969) are the families Nymphonidae and Pallenidae. The main
Antarctic genus of the family Nymphonidae is the genus Nymphon and
Gordon (1932) who attempted a revision has indicated some of the
difEoulties encountered in dealing with this group systematically. Dr
Gordon, herself, has indicated that her conclusions are tentative. She
keys some 31 Antarctic and Subantarctic species of the genus, which
would appear to be another good example of radiative evolution amongst
Antarctic animals.
Fry (1965) was able to study two live Antarctic species at McMurdo
Sound, Austrodecus glaciale and Rhynchothorax australis Hodgson. He
was particularly concerned with the food preferences of these two species,
which occurred in comparable numbers in approximately 280 m.
Specimens of Rhynchothorax were observed to ingest polyps of the
hydroid Eudendrium tottoni Stechow and in experimental work associated itself with this hydroid in preference to all other potential foods
offered. Austrodecus showed a marked preference for association with
the polyzoan Cellarinella foveolata Waters. Fry was able to show that
the h e pointed proboscis of Austrodecus glaciale would allow it to
probe through the frontal wall pores of the zooecium and so gain access
to the coelom of the polypides of Cellarinella. Austrodecus also requires
a leg span of about 10 mm or more to provide a 6rm platform for feeding. Only Cellarinella of the available polyzoans had frontal wall pores
large enough to allow the proboscis of A. glaciale to penetrate, in addition to supplying a broad, firm colony.
The Discovery collections included males of 16 species carrying eggs
or larvae. The dates of collection were from October to April (more
concentrated from December to March). In the Magellan area all such
males were collected in July (Gordon, 1932).
Many Antarctic pycnogonids have been collected encrusted with
other organisms. Gordon (1932) records mainly Polyzoa, Foraminifera
and hydroids, and occasionally brachiopods, sponges, tunicates and
serpulids. Occasional isopods have also been recorded clinging to
pycnogonids. Decolopoda antarctica is usually much more heavily
encrusted than D. australis, evidence presumably that D. antarctica is
a fairly sluggish animal.
Hedgpeth (1964, p. 45) has recorded the eggs of a prosobranch
attached to the legs of Antarctic pycnogonids from Eltanin Stations 410
(61"18'5, 56"08'3O''W, 120-131 fm) and 437 (62'49'36"S, 60"40'W,