Elasmobranchii (sharks and rays) > Squaliformes
(Sleeper and dogfish sharks) > Somniosidae
Etymology: Somniosus: Latin, somnus = sleep (Ref. 45335).
Environment: milieu / climate zone / depth range / distribution range
Marine; benthopelagic; depth range - 2205 m (Ref. 119696), usually - m (Ref. ). Boreal; 0°C - ; 72°N - 23°N, 121°E - 110°W
North Pacific and Arctic: Taiwan to Japan and Kuril Islands, Sea of Okhotsk, southeastern Kamchatka, Commander and Aleutian Islands, and southern Baja California to Gulf of Alaska, Bering Sea and Chukchi Sea.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 440 cm TL male/unsexed; (Ref. 247); 430.0 cm TL (female)
soft rays: 0. Diagnosis: Somniosus pacificus differs from S. antarcticus by the following characters: interdorsal space about 70% of prebranchial length (vs. 80%); height of first dorsal fin about 3.7% of precaudal length (PCL) (vs. 3.0%); height of second dorsal fin about 3.4% of PCL (vs. 2.9%); number of turns in spiral valve 32-37 (mode 33) (vs. 36-41, mode 39); precaudal vertebrae 28-30 (mode 29) (vs. 30-31, mode 30) (Ref. 50224).
Demersal and mesobenthopelagic (Ref. 119696); found on continental shelves and slopes (Ref. 247). At high latitudes, occasionally occurs in littoral and even intertidal areas; in lower latitudes it may never come to the surface and ranges down to at least 2,000 m (Ref. 247), reported to about 2,205 m in the Hawaiian Is. as recorded by camera arrays (Ref. 119696). Feeds on bottom animals such as fishes, octopi, squids, crabs and tritons; also harbor seals and carrion (Ref. 247). Ovoviviparous (Ref. 205), with 300 pups in a litter (Ref. 247), length at birth about 42 cm or less (Ref. 26346). The flesh contains a type of toxin which, when eaten, produces symptoms of drunkenness (Ref. 583). Possibly reaches lengths greater than 700 cm (Ref. 247).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Probably ovoviviparous (Ref. 247). Size at birth 42 cm or less (Ref. 26346). Distinct pairing with embrace (Ref. 205).
Yano, K., J.D. Stevens and L.J.V. Compagno, 2004. A review of the systematics of the sleeper shark genus Somniosus with redescriptions of Somniosus (Somniosus) antarcticus and Somniosus (Rhinoscymnus) longus (Squaliformes: Somniosidae). Ichthyol. Res. 51:360-373. (Ref. 50224)
IUCN Red List Status (Ref. 124695)
Fisheries: of no interest
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Preferred temperature (Ref. 115969
): 0.5 - 4.5, mean 2.3 °C (based on 400 cells).
Phylogenetic diversity index (Ref. 82805
= 0.5313 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00631 (0.00340 - 0.01171), b=3.09 (2.93 - 3.25), in cm total length, based on LWR estimates for this species & (Sub)family-body (Ref. 93245
Trophic level (Ref. 69278
): 4.4 ±0.4 se; based on diet studies.
Resilience (Ref. 120179
): Low, minimum population doubling time 4.5 - 14 years (Fec=300; assuming tm<=10).
Vulnerability (Ref. 59153
): Very high vulnerability (89 of 100) .