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Species: Somniosus rostratus, Little Sleeper Shark

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slender body
D1 insertion nearer pectorals than pelvics
tail base: short keels
lower teeth: high, slender, semi-erect cusps
tooth rows: top 57-63, bottom 31-36

Somniosus rostratus (Risso, 1827)

Little Sleeper Shark

Body cylindrical, relatively slender; head short (snout to pectorals 20-23% TL); snout short, rounded, without barbels; eyes on side of head, without nictitating membranes; spiracles large, just behind eyes; mouth short, nearly transverse; top teeth narrow, needle-like, with a single cusp, non-overlapping, 57-63 rows; bottom teeth blades, overlapping, with high oblique cusps, 31-36 rows; gill slits 5, all before pectoral fin; 2 dorsal fins without spines; 1st dorsal higher & slightly larger than 2nd dorsal; origin of 1st dorsal in middle of back, insertion closer to pectorals than pelvics; no anal fin; pelvic fins ~equal to or larger than 2nd dorsal; tail base short (distance between 2nd dorsal base and upper tail fin origin </= 2X 2nd dorsal fin base); tail fin strongly asymmetrical, paddle shaped, lower lobe long, moderately large; short keels before base of tail fin; skin smooth, flank denticles with flat, wide crowns and horizontal points.

Uniform blackish.

Reaches 143 cm.

Depth range 180-2200 m.


North Atlantic and Mediterranean; Cuba and NE Yucatan.

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  • Marine
  • Marine Only
  • Offshore
  • Offshore Only
Water Column Position
  • Bottom
  • Bottom + water column
  • Near Bottom
  • Rocks
  • Sand & gravel
  • Water column
  • Mud
  • Reef (rock/coral/oyster)
  • Reef and soft bottom
  • Reef associated (reef + edges-water column & soft bottom)
FishBase Habitat
  • Bentho-Pelagic
  • Reef Associated
Feeding Group
  • Carnivore
  • Data
  • Data
  • Octopus/squid/cuttlefish
Egg Type
  • Data
  • Live birth
Global Endemism
  • All species
  • Greater Caribbean non-endemic
  • Transatlantic (East+West Atlantic)
Regional Endemism
  • GC non-endemic
  • Island (s)
  • Island (s) only
  • All species
  • Vagrant
Climate Zone
  • Subtropical (23-35N, Florida / Carolinas / Bermuda)
IUCN Red List
  • Data deficient
  • Listed
  • Not listed
Length Max
  • 143
Depth Range Min
  • 180
Depth Range Max
  • 2200