Squalidae, also called dogfish sharks, dog sharks, or spiny dogfish,[2] are a family of sharks in the order Squaliformes. Dogfish sharks make up the second largest order of sharks at 119 species. They have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch.[1] Dogfish tend to have slender bodies with a pointed snout. These species are also known to be more compact in comparison to other sharks. As the species reaches adulthood, males usually measure a maximum of 39 inches (990 mm), while females typically measure 49 inches (1,200 mm) long. The species therefore exhibits female-dominant sexual dimorphism. Dogfish sharks earned their name after a group of fishermen observed the species chasing down smaller fish in dog-like packs.[3]
Dogfish sharks have grayish-brown skin with white dots that becomes paler (almost white) around the belly region. These sharks are characterized by teeth in upper and lower jaws similar in size; a caudal peduncle with lateral keels; the upper usually is present; and the caudal fin is without a subterminal notch.
They are carnivorous, principally preying upon organisms smaller than themselves. Some of their prey include herring, mackerel, and capelin. In special cases, they may consume jellyfish and squid. Even at a young age, spiny dogfish pups may hunt fish two or three times their size.[citation needed] Unlike virtually all other shark species, dogfish sharks possess venom which coats their dorsal spines; this venom is mildly toxic to humans and would be harmful if the shark were to be mishandled. The livers and stomachs of the Squalidae contain the compound squalamine, which possesses the property of reduction of small blood vessel growth in humans.[4] Dogfish sharks use their strong jaw and sharp teeth to consume their prey.
The spiny dogfish has broken several records in the areas of migration and gestation. This shark tends to be a highly migratory species: one shark was recorded as traveling 5,000 miles (8,000 km) after being tagged in Washington state, United States, and found again later in Japan. In addition to its long distance migration, the spiny shark holds the record for longest gestation period of any other vertebrate at 22-24 months. Females produce eggs and give birth to live young that measure to be 7.9–13.0 inches (20–33 cm).
Two genera are known: Squalus, which contains numerous species, and Cirrhigaleus, which has three species.
References[]
^ Jump up to: abFroese, Rainer, and Daniel Pauly, eds. (2009). "Squalidae" in FishBase. January 2009 version.
^"Squalidae". Integrated Taxonomic Information System. Retrieved 16 November 2013.
