The fatspine spurdog, Squalus crassispinus, is a dogfish

Squaliformes

Squaliformes is an order of sharks that includes about 97 species in seven families.Members of the order have two dorsal fins, which usually possess spines, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size...

 of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Squalidae

Squalidae

Squalidae is the family of dogfish sharks. They are found in the Atlantic, Pacific, and Indian oceans, from tropical equatorial climates to the Arctic and Antarctic....

, found on the continental shelf

Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 off the northern coast of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

, at depths of 180 to 200 m (590.6 to 656.2 ). The length of the longest male specimen measured is 56 centimetres (22 in).

The fatspine spurdog is a rare, small and slender dogfish with a broad head and short snout. There is a broad, small medial barbel

Barbel (anatomy)

A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...

 on the anterior nasal flaps. The pectoral fin has a shallowly concave posterior margin. The first dorsal fin

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 is moderately high, and both dorsal fin spines are very stout.

Coloration is light grey above, paler below, with no white spots. The pale dorsal fins have dusky tips.

Its reproduction is ovoviviparous.