THE GENERAL BIOLOGY OF PENGUINS
167
( a ) Crustacea
Euphausia superba, a densely swarming crustacean restricted to offshore waters south of the Antarctic convergence, forms the staple diet of
pygoscelid penguins in the Scotia Arc and along much of the continental
coast. Inshore and in the shallow waters of the Ross Sea its place is taken
by E . crystallorophias. Other euphausids, mostly unidentified, have been
reported from Macaroni penguins (Murphy, 1936, p. 437), Emperors in
pack ice (Falla, 1.937, p. 40) and Rockhoppers on Kerguelen (Falla, 1937,
p. 91). A succession of species occupies overlapping latitudinal zones in
the Indian Ocean. North of the Antarctic convergence the richest
euphausid concentrations lie in the southern part of the sub-tropical
zone, between 30 and 40”S, where E . recurva and E . hemigibba become
especially prominent (Baker, 1965, p. 327). It would be interesting to
know if these species form an important part of the diet of Rockhoppers
on St. Paul and New Amsterdam. “Krill” (generally but not always
referring to dense euphausid shoals) is also prominent off Chile (Gunther,
1936, p. 177) but does not seem t o be an important food of the local
spheniscid penguins. “Lobster-krill” - swarming pelagic larvae of anomuran crustacea Munida subruyosa and M . gregarian are seasonally
prominent off New Zealand and its southern islands, the Bass Strait,
Falklands, Magellanic region and Patagonia, usually in water a t 5.59°C (Matthews, 1932, p. 470). They often appear in association with
mysids and copepods, on which they feed, and in turn they become the
food of many fish, and almost certainly of eudyptid penguins (possibly also
Gentoos) within their range. The swarming mysid Arctomysis marina
has been recorded by Murphy (1936, p. 377) from Gentoo penguins in
South Georgia, and the amphipod Themisto gaudichaudi was recorded
in Rockhoppers and other birds on Tristan da Cunha by Hagen (1952,
p. 29).
(b) Cephalopods
Although elusive to marine biologists, squid are an important item in
the diet of many marine carnivores. Unidentified species (possibly
Onychoteuthis or Moroteuthis spp.) form the bulk of King penguin food
throughout the year at South Georgia (Stonehouse, 1960, p. 54), probably
also of Emperors (including Psychoteuthis glacialis.; Murphy, 1936, p.
364). Squid have also been recorded, usually as beaks only, from Gentoo,
Addlie, Macaroni, Rockhopper, Magellanic, Blackfooted, Fjordland and
Yellow-eyed penguins. Little is known of their ecology or distribution
in southern waters. They are taken by many non-diving birds (e.g.
albatrosses, mollymawks and smaller pettrek) and must be available in
large quantities at the surface, perhaps especially a t night.
167
( a ) Crustacea
Euphausia superba, a densely swarming crustacean restricted to offshore waters south of the Antarctic convergence, forms the staple diet of
pygoscelid penguins in the Scotia Arc and along much of the continental
coast. Inshore and in the shallow waters of the Ross Sea its place is taken
by E . crystallorophias. Other euphausids, mostly unidentified, have been
reported from Macaroni penguins (Murphy, 1936, p. 437), Emperors in
pack ice (Falla, 1.937, p. 40) and Rockhoppers on Kerguelen (Falla, 1937,
p. 91). A succession of species occupies overlapping latitudinal zones in
the Indian Ocean. North of the Antarctic convergence the richest
euphausid concentrations lie in the southern part of the sub-tropical
zone, between 30 and 40”S, where E . recurva and E . hemigibba become
especially prominent (Baker, 1965, p. 327). It would be interesting to
know if these species form an important part of the diet of Rockhoppers
on St. Paul and New Amsterdam. “Krill” (generally but not always
referring to dense euphausid shoals) is also prominent off Chile (Gunther,
1936, p. 177) but does not seem t o be an important food of the local
spheniscid penguins. “Lobster-krill” - swarming pelagic larvae of anomuran crustacea Munida subruyosa and M . gregarian are seasonally
prominent off New Zealand and its southern islands, the Bass Strait,
Falklands, Magellanic region and Patagonia, usually in water a t 5.59°C (Matthews, 1932, p. 470). They often appear in association with
mysids and copepods, on which they feed, and in turn they become the
food of many fish, and almost certainly of eudyptid penguins (possibly also
Gentoos) within their range. The swarming mysid Arctomysis marina
has been recorded by Murphy (1936, p. 377) from Gentoo penguins in
South Georgia, and the amphipod Themisto gaudichaudi was recorded
in Rockhoppers and other birds on Tristan da Cunha by Hagen (1952,
p. 29).
(b) Cephalopods
Although elusive to marine biologists, squid are an important item in
the diet of many marine carnivores. Unidentified species (possibly
Onychoteuthis or Moroteuthis spp.) form the bulk of King penguin food
throughout the year at South Georgia (Stonehouse, 1960, p. 54), probably
also of Emperors (including Psychoteuthis glacialis.; Murphy, 1936, p.
364). Squid have also been recorded, usually as beaks only, from Gentoo,
Addlie, Macaroni, Rockhopper, Magellanic, Blackfooted, Fjordland and
Yellow-eyed penguins. Little is known of their ecology or distribution
in southern waters. They are taken by many non-diving birds (e.g.
albatrosses, mollymawks and smaller pettrek) and must be available in
large quantities at the surface, perhaps especially a t night.