REVIEW OF THE SYSTEMATICS AND ECOLOGY OF OCEANIC
SQUIDS
167
and later from other stations in the Indian Ocean (Chun, 1910a;
Massy, 1916b), South Africa (Chun, 1910a; Thiele, 1921), the South
Atlantic (Pfeffer, 1912; Thiele, 1921; Odhner, 1923), north Sumatra
(Massy, 1916b), the Southern Ocean (Hoyle, 1886a, 1912; Thiele, 1921;
Clarke unpublished), the North Atlantic (Verrill, 1885a; Hoyle, 1904b;
Massy, 1916a, 1928a; Joubin, 1920, 1924; Thiele, 1921; Voss, 195613,
1960a) the Mediterranean (Pfeffer, 1912) and the eastern Pacific (Hoyle,
1904b; Robson, 1948). Specimens in the Discovery collections not
previously reported are added to Fig. 28. All published records were
taken with open nets and it is not always clear whether the depth given
is that of the net or that of the water. However, the maximum depth of
the deepest net which caught the species was 4200 m (Hoyle, 1912)
and the maximum depth of the shallowest net was 400 m (Pfeffer, 1912).
Discovery specimens, however, were caught with open nets (bearing
a depth of net indicator) as shallow as 100 m at night and seven times
with closing nets between 700 and 2 000 m (at 1 800-1 500 m, 1 050550 m, 850-950 m, 700-1 400 m, 1 800-2 000 m, 1 500-1 600 m and
1 200-1 300 m). I n view of the very large numbers of nets fished from
Discovery I I in the Antarctic regions a t all depths these seven
hauls are strongly indicative that the species normally lives between
700 m and 2 000 m in those regions. Specimens caught a t shallower
depths are all from the lower southern latitudes, the North Atlantic
Discovery collections) and the Mediterranean (Pfeffer, 1912). The
species is usually found over very deep water; in the ten Discovery I1
stations a t which the soundings were accurately measured and Bathyteuthis was taken, they varied between 3 569 and 5 460 m although
Massy (1916a) recorded them over soundings of 1280-1 370 m. The
Discovery material shows that the species has a tolerance of salinity
at least between 34.20°/,, and 34*98°/,0 and temperature between
1.50"C and 3.35"C. It does not appear to be confined to a particular
density of water and in the only three instances where there is information it was found below and within 700 m of the oxygen minimum
layer.
The species is very distinctive a t all stages, the smallest being
miniature adults except that they have prominent light organs at the
bases of the three dorsal pairs of arms. With regard to the latter
structures Voss (1956b) noted their absence in his own, Verrill's (1885a)
and Hoyle's (1885a) descriptions, but all these have a mantle length
of over 4.0 cm and a good series in the Discovery collections shows
that the organs are lost, or become invisible from the surface, between
mantle lengths of 2.28 and 3.7 cm. This series also shows that sexual
maturity in the female is reached between 3.75 and 6.15 cm in mantle
SQUIDS
167
and later from other stations in the Indian Ocean (Chun, 1910a;
Massy, 1916b), South Africa (Chun, 1910a; Thiele, 1921), the South
Atlantic (Pfeffer, 1912; Thiele, 1921; Odhner, 1923), north Sumatra
(Massy, 1916b), the Southern Ocean (Hoyle, 1886a, 1912; Thiele, 1921;
Clarke unpublished), the North Atlantic (Verrill, 1885a; Hoyle, 1904b;
Massy, 1916a, 1928a; Joubin, 1920, 1924; Thiele, 1921; Voss, 195613,
1960a) the Mediterranean (Pfeffer, 1912) and the eastern Pacific (Hoyle,
1904b; Robson, 1948). Specimens in the Discovery collections not
previously reported are added to Fig. 28. All published records were
taken with open nets and it is not always clear whether the depth given
is that of the net or that of the water. However, the maximum depth of
the deepest net which caught the species was 4200 m (Hoyle, 1912)
and the maximum depth of the shallowest net was 400 m (Pfeffer, 1912).
Discovery specimens, however, were caught with open nets (bearing
a depth of net indicator) as shallow as 100 m at night and seven times
with closing nets between 700 and 2 000 m (at 1 800-1 500 m, 1 050550 m, 850-950 m, 700-1 400 m, 1 800-2 000 m, 1 500-1 600 m and
1 200-1 300 m). I n view of the very large numbers of nets fished from
Discovery I I in the Antarctic regions a t all depths these seven
hauls are strongly indicative that the species normally lives between
700 m and 2 000 m in those regions. Specimens caught a t shallower
depths are all from the lower southern latitudes, the North Atlantic
Discovery collections) and the Mediterranean (Pfeffer, 1912). The
species is usually found over very deep water; in the ten Discovery I1
stations a t which the soundings were accurately measured and Bathyteuthis was taken, they varied between 3 569 and 5 460 m although
Massy (1916a) recorded them over soundings of 1280-1 370 m. The
Discovery material shows that the species has a tolerance of salinity
at least between 34.20°/,, and 34*98°/,0 and temperature between
1.50"C and 3.35"C. It does not appear to be confined to a particular
density of water and in the only three instances where there is information it was found below and within 700 m of the oxygen minimum
layer.
The species is very distinctive a t all stages, the smallest being
miniature adults except that they have prominent light organs at the
bases of the three dorsal pairs of arms. With regard to the latter
structures Voss (1956b) noted their absence in his own, Verrill's (1885a)
and Hoyle's (1885a) descriptions, but all these have a mantle length
of over 4.0 cm and a good series in the Discovery collections shows
that the organs are lost, or become invisible from the surface, between
mantle lengths of 2.28 and 3.7 cm. This series also shows that sexual
maturity in the female is reached between 3.75 and 6.15 cm in mantle