58
THE BIOLOGY O F EUPHAUSIIDS
Recorded as far west as 145"W in the Northern Equatorial Current and
164"W in the Southern Equatorial Current. Not present in the
Equatorial Countercurrent (2"N-10"N) nor in the coastal waters of
Colombia and Ecuador (5ON-5"S). Found between 140 and 700m
depth during the day but almost entirely above 140m a t night.
25-30 mm in length. (Hansen, 1915; Bacescu and Mayer, 1961 ;
Boden, 1961a; Brinton, 1962a; Roger, 1967a,b.)
Euphausia krohnii (Brandt, 1851)
Thysanopoda krohnii Brandt, 1851 : 127. Euphausia miilleri Claus, 1863:
444, pls. xxviii-xxix, figs. 29-45. Thysanopoda bidentutu G. 0. Sars, 1883a:
50-51, taf. 1, figs. 11-14. E. pellucida G. 0. Sam, 1885: 75-78, pls. xi, xii (partim) ;
Holt and Tattersall, 1905a: 101-102. E. krohnii Hansen, 1910: 90; 1911: 22,
fig. 4 ; Denis, 1929: 71-72.
Confined to the Atlantic and Mediterranean between about 5"-1OcN
and 66"N but does not breed in the northern part of this area (Fig. 17).
Its distribution is similar to that of Meganyctiphanes norvegica except
that it does not penetrate so far north as does M . norvegica nor does
it occur in coastal waters to the same degree. Einarsson considers that
its breeding area is limited in the north by the 10°C isotherm a t 100 m
depth so that no breeding takes place north of about 50"N. The early
records of Tattersall and Illig extend the southern area of occurrence
but it probably rarely penetrates farther south than about 10"N. This
species is replaced in oceanic areas by E. americana. Occurs nearer the
surface, 0 to 400 m, during the day than E . americana; performs a
diurnal vertical migration. Length 16 mm. (Tattersall, 1908b, 1911,
1913, 1927; Hansen, 1915; Colosi, 1922b; Lebour, 1926d, 1950; Denis,
1929; Illig, 1930; Frost, 1934; Leavitt, 1935, 1938; Ruud, 1936;
Einarsson, 1945 ; Whiteley, 1948 ; Fraser and Saville, 1949 ; Fraser,
1950, 1961 ; Moore, 1950, 1952 ; Kielhorn, 1952 ; Ostvedt, 1955; Dion
and Nouvel, 1960; Furnestin, 1960; Grice and Hart, 1962; Kinzer,
1963 ; Soulier, 1963a,b; Casanova-Soulier, 1968b.)
Euphausia mutica Hansen, 1905
E. mutica Hansen, 1905b: 14-15 (purtim); 1910: 93-94, pl. xiv, fig. 1, a-d;
Boden et al., 1955 : 326-328, fig. 20.
It occurs in the Atlantic, Pacific and Indian Oceans (Fig. 18).
Atlantic : present between 40"N and 40"s but not occurring throughout
the whole area, tending to live inside the 4 000m depth contour.
Pacific: has a similar distribution in the North Pacific to that of
E. recurva. Found in the offshore part of the California Current and
right across the North Pacific south of 40"N to 43"N but not, in the
THE BIOLOGY O F EUPHAUSIIDS
Recorded as far west as 145"W in the Northern Equatorial Current and
164"W in the Southern Equatorial Current. Not present in the
Equatorial Countercurrent (2"N-10"N) nor in the coastal waters of
Colombia and Ecuador (5ON-5"S). Found between 140 and 700m
depth during the day but almost entirely above 140m a t night.
25-30 mm in length. (Hansen, 1915; Bacescu and Mayer, 1961 ;
Boden, 1961a; Brinton, 1962a; Roger, 1967a,b.)
Euphausia krohnii (Brandt, 1851)
Thysanopoda krohnii Brandt, 1851 : 127. Euphausia miilleri Claus, 1863:
444, pls. xxviii-xxix, figs. 29-45. Thysanopoda bidentutu G. 0. Sars, 1883a:
50-51, taf. 1, figs. 11-14. E. pellucida G. 0. Sam, 1885: 75-78, pls. xi, xii (partim) ;
Holt and Tattersall, 1905a: 101-102. E. krohnii Hansen, 1910: 90; 1911: 22,
fig. 4 ; Denis, 1929: 71-72.
Confined to the Atlantic and Mediterranean between about 5"-1OcN
and 66"N but does not breed in the northern part of this area (Fig. 17).
Its distribution is similar to that of Meganyctiphanes norvegica except
that it does not penetrate so far north as does M . norvegica nor does
it occur in coastal waters to the same degree. Einarsson considers that
its breeding area is limited in the north by the 10°C isotherm a t 100 m
depth so that no breeding takes place north of about 50"N. The early
records of Tattersall and Illig extend the southern area of occurrence
but it probably rarely penetrates farther south than about 10"N. This
species is replaced in oceanic areas by E. americana. Occurs nearer the
surface, 0 to 400 m, during the day than E . americana; performs a
diurnal vertical migration. Length 16 mm. (Tattersall, 1908b, 1911,
1913, 1927; Hansen, 1915; Colosi, 1922b; Lebour, 1926d, 1950; Denis,
1929; Illig, 1930; Frost, 1934; Leavitt, 1935, 1938; Ruud, 1936;
Einarsson, 1945 ; Whiteley, 1948 ; Fraser and Saville, 1949 ; Fraser,
1950, 1961 ; Moore, 1950, 1952 ; Kielhorn, 1952 ; Ostvedt, 1955; Dion
and Nouvel, 1960; Furnestin, 1960; Grice and Hart, 1962; Kinzer,
1963 ; Soulier, 1963a,b; Casanova-Soulier, 1968b.)
Euphausia mutica Hansen, 1905
E. mutica Hansen, 1905b: 14-15 (purtim); 1910: 93-94, pl. xiv, fig. 1, a-d;
Boden et al., 1955 : 326-328, fig. 20.
It occurs in the Atlantic, Pacific and Indian Oceans (Fig. 18).
Atlantic : present between 40"N and 40"s but not occurring throughout
the whole area, tending to live inside the 4 000m depth contour.
Pacific: has a similar distribution in the North Pacific to that of
E. recurva. Found in the offshore part of the California Current and
right across the North Pacific south of 40"N to 43"N but not, in the