Bentheuphausia amblyops G.O. Sars, 1885
Etymology: Bentheuphausia - depth of the sea, shining brightly; amblyops - blunt-eyed
Eye: The eye is very small, oval, and reddish-brown, with ommatidia imperfectly developed; there are no photophores present (Bentheuphausia-photophores). The eye diameter : carapace length is about 0.08. There is a small, knob-like projection (tubercle) located on the upper anterior edge of the eyestalk adjacent to the eye (B. amblyops eye detail photo).
Peduncle of 1st Antenna: The peduncle appears stout or massive. The 1st and 2nd segments are particularly high, with the dorsal portions of each extending forward as plates 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 1st antenna is heavily setose in the male and less so in the female (B. amblyops,).
Rostrum: It is short, scarcely an acute triangle extending forward to the mid-point of the eye (B. amblyops eye & rostrum).
Carapace: There are no lateral denticles in the adult. In young specimens of about 8-17 mm, the postero-lateral margin is serrated (B. amblyops B ).
Abdomen: The abdomen is uniform and symmetrical, without keels or spines. The 6th segment is short, 1.3 times longer than its maximum vertical dimension.
Length: Adults are 25-50 mm.
Petasma: The endopod of the 1st 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).
Thelycum: Described by Guglielmo and Costanzo, 1983.
Comments: B. amblyops is the only species in the family. Fresh specimens are a deep red color, except for the white gills. There are no luminescent organs (Bentheuphausia-photophores).
ECOLOGY
B. amblyops is a food source for demersal fishes.
HORIZONTAL DISTRIBUTION
B. amblyops is one of the most widely distributed euphausiids. It has been found 54°N-54°S in the Pacific, 64°N-44°S in the Atlantic and in the tropical Indian ocean basins (B. amblyops distribution).
VERTICAL DISTRIBUTION
B. amblyops is a cosmopolitan species living in deep water probably 500-2000+m. It has been captured in all regions of the Pacific where the depth of the ocean is greater than 1,000 meters. No day-night difference is evident in the vertical distribution.
LARVAE
Because little is known of this species, information is presented in a format different from that for other species.
B. amblyops larvae occur at depths below ~1000 m. They are sparse and rarely intact in net-samples. Like adults, they are bright red.
The "degenerate" eye of the adult is similar to the undeveloped eye of the larvae. The forms shown in (B. amblyops Table) show the early appearance of rudiments of all 8 thoracic legs and the clarity of their similar progressive development.
An anteriorly-projecting carapace extends over the eye providing a calyptopis-like appearance in the larvae together with pleopod development typical of the furcilia phase in many other euphausiids. (B. amblyops A)
Earliest juveniles (8+ mm in length) develop a postero-lateral marginal row of serrations, first visable as ~5 serrations, increasing to about 15 or 18, disappearing at ~17 mm body length. These characters are not found in other euphausiids. (B. amblyops B)
Similarity in the body-length ranges of these different forms suggests slow and/or variable growth rates.
Based on the early appearance of all 8 thoracic legs and the lack of pigment in the eye these specimens are referred to Bentheuphausia amblyops .
Pictures
B. amblyops, selected stages
B. amblyops A
B. amblyops B
B. amblyops Table [early developmental forms]
key to larval illustrations