Dogfish feed on squid.
The term dogfish refers to sharks that belong to the order Squaliformes, especially the family Squalidae, which are found in many of the world’s oceans. It is the common name for many of the 119 species of small and medium-sized sharks that belong to this group. The most populous of the group is the spiny dogfish, one of the most abundant of all sharks. The dogfish has several shared characteristics, including fin arrangement, bioluminescence, diet, and oviparous reproductive development.
Dogfish are found in most of the world’s oceans, with temperatures ranging from tropical to subarctic. They tend to stay in the lower, cooler depths most of the time, though they do travel to greater depths for short periods in cooler waters. Some species can also be found in coastal areas. In some areas they are harvested for food and other uses, and many species are in danger of extinction due to this practice.
Dogfish vary in size depending on the species, from 48 cm (19 in) to 1.6 m (5.2 ft) in length. Most species have rounded bodies, with the mouth located at the bottom, slightly behind the snout. The skin usually has a rough sandy feel, with five gill slits on each side of the head. It has two dorsal fins with spines, but usually no anal fin; in many species, these spines are covered in venom, a feature unique to this type of shark. Many of the species have different levels of bioluminescence, meaning they appear to glow when in darker areas, as if lit from within.
As most species are carnivorous, the dogfish’s diet generally consists of whatever smaller animals are readily available. This can include invertebrates such as jellyfish, crabs, krill, squid and octopus or other fish such as cod, herring and haddock. One species, also known as the cookie cutter shark, actually rips a piece of meat from its prey without eating the entire organism.
The reproductive development of the shark shark is oviparous. This means that the eggs develop inside the mother’s body after fertilization by the man and the babies are born alive. During development, the babies are supported by a yolk sac, and the mother shark gives birth after a gestation period of various lengths, depending on the species. One species, the dogfish, typically has the longest known gestation period, lasting 18 to 22 months, and the average litter size is five to six babies, known as pups.