Elasmobranchii (sharks and rays) > Squaliformes
(Bramble, sleeper and dogfish sharks) > Somniosidae
Etymology: Somniosus: Latin, somnus = sleep (Ref. 45335).
Environment / Climate / Range
Marine; benthopelagic; depth range 0 - 2000 m (Ref. 26346). Temperate, preferred 18°C (Ref. 107945); 70°N - 47°S
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).
Found on continental shelves and slopes (Ref. 247). At high latitudes, it 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). 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. 96402)
CITES (Ref. 94142)
Fisheries: of no interest
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5313 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00661 (0.00356 - 0.01226), b=3.08 (2.92 - 3.24), 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. 69278
): Low, minimum population doubling time 4.5 - 14 years (Fec=300; assuming tm<=10).
Vulnerability (Ref. 59153
): Very high vulnerability (87 of 100) .