To see photographs of Dogsharks click here.
Dogsharks. Dogfish Sharks. Squalidae species.
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protected: © 2002 Kelvin Aitken.
All rights reserved. Students may use this information for personal research
only. Not for commercial use.
Dogfish are the largest shark family in Australia with 40 species. They
range from the smallest of all sharks, the Smalleye Pygmy Shark (Squaliolus
aliae), at 22 cm long, to the huge 6 m long Pacific Sleeper Shark (Somniosus
pacificus). All dogfish have large spiracles, two dorsal fins, often with
a sharp defensive spine, and lack an anal fin.
Most species are deep-water dwellers, inhabiting the 100–2000 m depth
range, but some, like the White-Spotted Spurdog that lives on the southern
coast, can be found in shallow bays. It would be unusual for any diver
or snorkeler to see a dogfish but anglers find them regularly and some
species are an important component of the commercial catch.
The 50 cm long Cookie Cutter Shark (Isistius brasiliensis) is a notorious
hit-and-run merchant. During the night it migrates from the depths to
the surface and latches itself onto any large animal, such as a tuna,
dolphin or whale. It then removes a plug of flesh from its victim before
racing away. The lips act as a suction cup to hold it onto the side of
its host, while the pointed upper teeth grasp the flesh. The lower teeth
are blade-like and slice out a circular chunk of meat as the shark spins
on its axis.
Lantern sharks are a group of dogfish that glow in the dark. Their bellies,
flanks and tails have luminescent organs that may attract prey or help
hide them from the predators beneath as the glow blends in with the faint
star- or moonlight at the surface.