Euphausia mucronata

Euphausia mucronata G.O.Sars, 1883

Etymology: Euphausia - brightly shining; mucronata - pointed

Eye: The eye is round and large (E. mucronata eye & rostrum). The eye diameter : carapace length is about 0.22.

Peduncle of 1st Antenna: The 1st segment has a short, deeply bifid lobe with the two acute teeth directed forward, overlapping the 2nd segment slightly. The inner tooth is usually longer and stouter than the outer tooth. The 2nd segment is longer than the 3rd. The 3rd segment has a high dorsal keel that is produced anteriorly as an acute denticle (E. mucronata,).

Rostrum: There is no rostrum. The frontal plate is very short and obliquely triangular with a rounded tip (E. mucronata eye & rostrum).

Carapace: The gastric area is angularly vaulted. A low median keel extends anteriorly from the vaulted area to near the base of the frontal plate. There is one pair of lateral denticles (E. mucronata carapace denticle).

Abdomen: The 3rd segment has a strong mid-dorsal spine, and the 4th and 5th segments each have a corresponding medial sharp angle or a very short denticle (E. mucronata abdominal spines).

Length: Adults are 17-22 mm.

Petasma: The terminal process has a strong protruding heel. The process is distally bent, ending as a flattened oblong expansion. The proximal process has two bends, one near the base and another near the middle; it ends as an expanded iregularly curved plate which has a sharp protruding angle on its proximal part. The lateral process has no tooth at the bend. The additional process is a straight spine (E. mucronata petasma).

Thelycum: Described by Guglielmo and Costanzo, 1978.

Comments: It can be distinguished by its very large eyes, small denticles on margin of the 4th and 5th abdominal segments, the bifid lobe of the 1st segment of the peduncle of the 1st antenna and the lack of a process or lamella on the 2nd segment.

ECOLOGY
E. mucronata is an important food source for whales and fish, and has been reported to feed actively on detrital material at depth in the daytime (Antezana, 1978).

HORIZONTAL DISTRIBUTION
E. mucronata is restricted to the Peru-Chile Current between 5°S and about 41°S, the northern limit of Chile's fjords (E. mucronata distribution).

VERTICAL DISTRIBUTION
E. mucronata is reported to live near 300 m during the day and rise to the surface at night.

LARVAE
Undescribed.

Data on larval forms in the furcilia phase, provided by Antezana (1978), are summarized in the developmental summary (E. mucronata Table).

Development
(E. mucronata Table), development summary for the stage descriptors and length in stage.

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