Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under

Squaliformes The Squaliformes are an order of sharks that includes about 126 species in seven families. Members of the order have two dorsal fins, which usually possess spines, they usually have a sharp head, no anal fin or nictitating membrane, and fi ...

, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. 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 have slate-gray or gray-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 Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

with lateral keels; the upper precaudal pit 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 Mackerel is a common name applied to a number of different species of pelagic fish, mostly from the family Scombridae. They are found in both temperate and tropical seas, mostly living along the coast or offshore in the oceanic environment. ...

, and

capelin The capelin or caplin (''Mallotus villosus'') is a small forage fish of the smelt family found in the North Atlantic, North Pacific and Arctic oceans. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capel ...

. In special cases, they may consume

jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrel ...

and

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting ...

. Even at a young age, spiny dogfish pups may hunt fish two or three times their size. Unlike virtually all other shark species, dogfish sharks possess

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...

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 Squalamine is a steroid-polyamine conjugate compound with broad spectrum antimicrobial activity and anti-angiogenic activity. It was studied as a potential cancer drug and as a potential treatment for wet macular degeneration but as of 2018 had n ...

, which possesses the property of reduction of small blood vessel growth in humans.National Geographic June 1998 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 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 .

Taxonomy

Dogfish are scientifically classified as the Squalidae family, categorized under the

Squaliform The Squaliformes are an order of sharks that includes about 126 species in seven families. Members of the order have two dorsal fins, which usually possess spines, they usually have a sharp head, no anal fin or nictitating membrane, and fiv ...

order, which encompasses seven families in total, including Squalidae. The Squalidae family itself contains two separate genera: Cirrhigaleus and

Squalus ''Squalus'' is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper p ...

, numbering 37 species between the two. Squalus acanthias2

Taxonomy

References

Further reading