REVIEW OF THE SYSTEMATICS AND ECOLOGY OF OCEANIC SQUIDS
255
bottles shows conclusively that Ommastrephes caroli extends from the
surface to 1 490 m (Table 11).
The stomach contents of predators often give some information
on depth of squids. For example if species occur in bird stomachs
(e.g. Hyaloteuthis pelagicus) they must come very near the surface;
seals probably dive to less than about 200 m so that their food must
occur shallower than this. There are six records of Sperm whales
becoming entangled in telephone cables at about 1 000 m (Heezen, 1957)
which strongly substantiates the theory that they feed at great depths
on such species as Lepidoteuthis grimaldii, Histioteuthis bonellii,
Taningia danae, etc. Perhaps such species live near the bottom on the
continental slope at depths of around 1000 m because sand grains
have been taken from the stomach of Taningia danae.
Very few structural variations have been related to depth; such
features as luminescence, transparency, the possession of a silver
reflecting layer and large eyes all seem to be as prevalent in shallow aa
in deep living species. However, the one species known to come near
the sea surface in daylight, (Onychia carribaea) has a general blue
colouration which is seen in no other squid. Otherwise, colour seems
to vary quite independently with depth. There is some evidence that
pigment in the lens may vary with depth; Denton (I96Ob) found that
Onychoteuthis banksi, which probably spends some time near to the
sea surface, has a lens pigment which is yellower than other species
examined and squids living deeper have lenses transparent down to
about 310 mp. The yellow pigment would filter out much of the daylight penetrating the upper layers, a filtration unnecessary in deeper
living squids only illuminated by blue or green light.
XXIII. EW MASSES
Our almost complete ignorance of the eggs and early larval stages
of oegopsids is the most extraordinary omission in our knowledge of
cephalopod biology. From observation of egg laying females in shallow
water, it would appear that Todarodes pacificus lays its egg mass on
the bottom (page 136). On the other hand, except for a few references
to oegopsid eggs (Stephen, 1944; Allan, 1945) there is only the description of a Thysanoteuthis rhombus egg mass (Fig. 26, p. 161), Watasenia
scintillans eggs (Shimomura and Fukataki, 1957) and a few descriptions
of egg masses collected or seen at the surface. Collingwood (1873)
gave an admirable description of an egg mass collected in a bucket
from the surface at 37"N 28"W. The egg mass resembled " one of those
cylindrical knitted comforters worn by ladies " measured 2 ft long by
4 or 5 in. in diameter; was closed at both ends and floated " expanded
255
bottles shows conclusively that Ommastrephes caroli extends from the
surface to 1 490 m (Table 11).
The stomach contents of predators often give some information
on depth of squids. For example if species occur in bird stomachs
(e.g. Hyaloteuthis pelagicus) they must come very near the surface;
seals probably dive to less than about 200 m so that their food must
occur shallower than this. There are six records of Sperm whales
becoming entangled in telephone cables at about 1 000 m (Heezen, 1957)
which strongly substantiates the theory that they feed at great depths
on such species as Lepidoteuthis grimaldii, Histioteuthis bonellii,
Taningia danae, etc. Perhaps such species live near the bottom on the
continental slope at depths of around 1000 m because sand grains
have been taken from the stomach of Taningia danae.
Very few structural variations have been related to depth; such
features as luminescence, transparency, the possession of a silver
reflecting layer and large eyes all seem to be as prevalent in shallow aa
in deep living species. However, the one species known to come near
the sea surface in daylight, (Onychia carribaea) has a general blue
colouration which is seen in no other squid. Otherwise, colour seems
to vary quite independently with depth. There is some evidence that
pigment in the lens may vary with depth; Denton (I96Ob) found that
Onychoteuthis banksi, which probably spends some time near to the
sea surface, has a lens pigment which is yellower than other species
examined and squids living deeper have lenses transparent down to
about 310 mp. The yellow pigment would filter out much of the daylight penetrating the upper layers, a filtration unnecessary in deeper
living squids only illuminated by blue or green light.
XXIII. EW MASSES
Our almost complete ignorance of the eggs and early larval stages
of oegopsids is the most extraordinary omission in our knowledge of
cephalopod biology. From observation of egg laying females in shallow
water, it would appear that Todarodes pacificus lays its egg mass on
the bottom (page 136). On the other hand, except for a few references
to oegopsid eggs (Stephen, 1944; Allan, 1945) there is only the description of a Thysanoteuthis rhombus egg mass (Fig. 26, p. 161), Watasenia
scintillans eggs (Shimomura and Fukataki, 1957) and a few descriptions
of egg masses collected or seen at the surface. Collingwood (1873)
gave an admirable description of an egg mass collected in a bucket
from the surface at 37"N 28"W. The egg mass resembled " one of those
cylindrical knitted comforters worn by ladies " measured 2 ft long by
4 or 5 in. in diameter; was closed at both ends and floated " expanded