Guide to Shark Identification
Order Squaliformes — Dogfish Sharks
Dogfishes are generally bottom-oriented inhabitants of the deep-sea and thus few species are likely to be encountered by divers. All squaloids possess the following characteristics:
- spine along leading edge of one or both dorsal fins
anal fin absent- large, almond-shaped eyes
- large, conspicuous spiracle above and behind each eye
- many species are bioluminescent
Family Squalidae — Spiny Dogfish Sharks
Since only one species of spiny dogfish is regularly encountered by divers, for our purposes here, characteristics of the family Squalidae can be considered the same as for the squaloid order.
Spiny Dogfish (Squalus acanthias)
What to Look For:
- spine along leading edge of both dorsal fins
- first dorsal spine originates behind free rear tips of pectoral fins
- weak keel on tail stalk
- no subterminal notch on caudal fin
- young individuals have small white spots on flanks
Size: average length 2 to 3 feet (60 to 100 centimetres); maximum 5.5 feet (160 centimetres)
Habitat: Intertidal, Sandy Plains, Rocky Reefs, Deep Sea, Polar Seas
Distribution: Arctic, ?Antarctic, Temperate Eastern Pacific, Tropical Eastern Pacific, Chilean, Argentinean, Western North Atlantic, Eastern North Atlantic / Mediterranean, Southern African, Southeast Asian, Southeastern Australian/New Zealand, Japanese
