Thursday, January 24, 2008

Smooth Dogfish Shark


The smooth dogfish has a slender body with an obvious spiracle behind the eye. The caudal fin has a rounded lower lobe and a larger top lobe. The teeth are very small, blunt, numerous and similar in both the upper and lower jaw. This shark is olive gray or brown on top and yellow or grayish white below. The smooth dogfish is able to change its colour slowly through contraction of melanophores (migratory pigment cells that through contraction or relaxation give the impression of a colour change). This shark grows to 1.5 meters (5 feet) in length. It is primarily nocturnal.
This shark is a scavenger and opportunistic feeder, but regularly feeds upon crabs, lobster and shrimp.
The smooth dogfish is a viviparous shark giving birth to a litter of 10 to 20 pups. Gestation is 10 months long and the young are usually delivered in the summer months. The pups are 34 to 39 cm (13 to 15 inches) at birth. Sexual maturity is reached when individuals reach 85 cm (33 inches) in length.
This shark commonly lives in bays and inshore waters. It prefers waters less than 18 meters (60 feet) deep. The smooth dogfish is a migratory species that moves north and south with the seasons.
This species of shark occurs in the western Atlantic Ocean. It ranges from the Bay of Fundy to Uruguay. It is a common shark in the waters off Cape Cod to Delaware Bay, and overwinters from Chesapeake Bay to South Carolina. It is rare in Canadian waters and the Bay of Fundy represents the northern most part of its range.