G.O. Sars, 1885
Description
Fresh specimens have a deep red colour; the gills are white and prominent, especially those on the thoracic legs 6-8. There are no luminescent organs.
The eye is very small, oval, and reddish-brown, with ommatidia imperfectly developed; there are no photophores present. The ratio of the eye diameter and the carapace length is about 0.08. [B.amblyops-eye-ph]. There is a small, knob-like projection (tubercle) located on the upper anterior edge of the eyestalk adjacent to the eye.
The peduncle of the first antenna appears stout or massive. The first and second segments are particularly high, with the dorsal portions of each extending forward as plates [B.amblyops lappet ] that appear to reinforce successive joints of the peduncle; the two distal segments are somewhat thicker in male than female. The basal part of the upper flagellum of the first antenna is heavily setose in the male and less so in the female.
Rostrum short, scarcely an acute triangle extending forward to the mid-point of the eye [B.amblyops-ph].
Carapace without lateral denticles in the adult. In young specimens of about 8-17 mm, the postero-lateral margin is serrated.
Thoracic legs all well developed; however, legs 8, 7, and 6 are notably smaller than the more anterior legs.
Abdomen is uniform and symmetrical, without keels or spines. The sixth segment is short, 1.3 times longer than its maximum vertical dimension. [B.amblyops-drawing]. Photophores absent.
Petasma: the endopod of the first pleopod is not modified as a complex petasma in the male, but the basipod carries 1-6 stout spines and the endopod bears a small lobe [B.amblyops petasma ].
Length
Adults are 25-50 mm.
Larval stages
Larva: B.amblyops-A
Juvenile B.amblyops-B
Ecology
B. amblyops is a food source for demersal fishes.
Depth range
B. amblyops is a bathypelagic species living in deep water, probably from 500 to >2000 m. No day-night difference is evident in the vertical distribution.
Distribution in the North Sea
This deep sea species is absent from the shallow North Sea. However, regarding the presence of B. amblyops in the adjacent waters of the NE Atlantic, the species is likely to occur in the northern North Sea, in the vicinity of the Orkney and Shetland Islands, as well as in the Norwegian Deep. Indeed, B. amblyops is reported from the entrance of the northern North Sea (S. Hay, pers. com.)
World distribution
B. amblyops is one of the most widely distributed euphausiids; found between 54°N and 54°S in the Pacific, between 64°N and 44°S in the Atlantic and in the tropical Indian Ocean basins.
Remark
B. amblyops is the only species in the family Bentheuphausiidae.
[After Brinton et al., 1999]