332
THE BIOLOGY OF EUPHAUSIIDS
Thysanopoda aequalis (? ), T . subaequalis; Meganyctiphanes norvegica; Nyctiphanes couchii; Euphausia eximia, E. krohnii, E. brevis, E .
hemigibba; ThysanoGsa gregaria; Nematoscelis megalops, N . atlantica,
N . microps(?); Stylocheiron suhmii, S. longicorne, 8. maximum, S.
abbreviatum.
Euphausia eximia is only found here, off northwest Africa and off
the Pacific coast of Central America; Bacescu and Mayer (1961)
obtained between one and thirty specimens at eleven stations and 237
at one station (36'14" 5'11'E) out of a total of thirty-six stations
located throughout the Mediterranean. Confusion exists in the literature between individuals of the pairs of species Thysanopoda aequalisl
T . subaequalis and Nematoscelis microps/iV. atlantica, and it is now
thought that neither Thysanopoda aequalis nor Nematoscelis microps
occurs in the Mediterranean but this requires confirmation. The two
northerly species, Meganyctiphanes norvegica and Nyctiphanes couchii,
more common in the Atlantic, are fairly common in northern and
western regions of the Mediterranean, there being resident populations
in the Balearic and Tyrrhenian Seas, the Gulf of Taranto, Adriatic and
northern Ionian Seas, and also in the Sea of Marmara. On the other
hand, Euphausia krohnii, Nematoscelis megalops and Stylocheiron
longicorne are common in the Atlantic but more common in the
Mediterranean, especially in northern and western areas (Fig. 123) but
also fairly common in southern and eastern areas. Euphausia brevis
and E. hemigibba, along with Thysanopoda aequalisl T . subaequalis,
Nematoscelis atlantica, and Stylocheiron suhmii are representatives of
the subtropical epipelagic species in the Atlantic and they occur most
commonly in the Mediterranean in the Tyrrhenian and Ionian Seas and
in areas further eastwards of these. The three deep sea species, Stylocheiron abbreviatum, S. maximum, and ThysanoGsa gregaria also occur,
the first two being rare although found throughout the Mediterranean
except in the Sea of Marmara while T . gregaria is probably not resident
in the Mediterranean but has a variable degree of occurrence throughout
the western regions where it intrudes with the inflowing water from the
Atlantic.
Atlantic ( 4OoN-4O0S)
Forty-four species are resident in this region but several of the
subantarctic and North Atlantic species have also been recorded north
of 40'5 and south of 40'N respectively. These latitudinal limits are
therefore only approximate guides in dividing the Atlantic to correspond
with changing hydrographical regimes and euphausiid communities.
THE BIOLOGY OF EUPHAUSIIDS
Thysanopoda aequalis (? ), T . subaequalis; Meganyctiphanes norvegica; Nyctiphanes couchii; Euphausia eximia, E. krohnii, E. brevis, E .
hemigibba; ThysanoGsa gregaria; Nematoscelis megalops, N . atlantica,
N . microps(?); Stylocheiron suhmii, S. longicorne, 8. maximum, S.
abbreviatum.
Euphausia eximia is only found here, off northwest Africa and off
the Pacific coast of Central America; Bacescu and Mayer (1961)
obtained between one and thirty specimens at eleven stations and 237
at one station (36'14" 5'11'E) out of a total of thirty-six stations
located throughout the Mediterranean. Confusion exists in the literature between individuals of the pairs of species Thysanopoda aequalisl
T . subaequalis and Nematoscelis microps/iV. atlantica, and it is now
thought that neither Thysanopoda aequalis nor Nematoscelis microps
occurs in the Mediterranean but this requires confirmation. The two
northerly species, Meganyctiphanes norvegica and Nyctiphanes couchii,
more common in the Atlantic, are fairly common in northern and
western regions of the Mediterranean, there being resident populations
in the Balearic and Tyrrhenian Seas, the Gulf of Taranto, Adriatic and
northern Ionian Seas, and also in the Sea of Marmara. On the other
hand, Euphausia krohnii, Nematoscelis megalops and Stylocheiron
longicorne are common in the Atlantic but more common in the
Mediterranean, especially in northern and western areas (Fig. 123) but
also fairly common in southern and eastern areas. Euphausia brevis
and E. hemigibba, along with Thysanopoda aequalisl T . subaequalis,
Nematoscelis atlantica, and Stylocheiron suhmii are representatives of
the subtropical epipelagic species in the Atlantic and they occur most
commonly in the Mediterranean in the Tyrrhenian and Ionian Seas and
in areas further eastwards of these. The three deep sea species, Stylocheiron abbreviatum, S. maximum, and ThysanoGsa gregaria also occur,
the first two being rare although found throughout the Mediterranean
except in the Sea of Marmara while T . gregaria is probably not resident
in the Mediterranean but has a variable degree of occurrence throughout
the western regions where it intrudes with the inflowing water from the
Atlantic.
Atlantic ( 4OoN-4O0S)
Forty-four species are resident in this region but several of the
subantarctic and North Atlantic species have also been recorded north
of 40'5 and south of 40'N respectively. These latitudinal limits are
therefore only approximate guides in dividing the Atlantic to correspond
with changing hydrographical regimes and euphausiid communities.