Thursday, August 4, 2011

Life of Smooth Dogfish Shark

Life of Sea | Smooth Dogfish Shark (Mustelus canis) | Smooth dogfish shark is also known as Dusky smooth-hound shark. Smooth dogfish shark is found in subtropical waters between 42°N-44°S and 100°W-46°W up to a max depth of 579 m deep. They are a migratory species found in abundance off the coasts of the US. Their range includes the western Atlantic from Massachusetts to Florida, the northern and western Gulf of Mexico, the coasts of Venezuela, Cuba, Jamaica, Barbados, Bermuda, Bahamas, and southern Brazil to northern Argentina, and the Antilles. The smooth dogfish tends to inhabit continental and insular shelves and upper slopes in depths that range from shallow inshore waters and the intertidal zone around 18 m up to the max depth of 579 m. Although this species has been seen in freshwater, it is unlikely that the smooth dogfish can survive in fresh water for extended periods.

Smooth dogfish shark measures about 150 cm in total length and weighs a maximum of 12.2 kg. This is a small shark species with two well-serrated dorsal fins almost equal in size. The first dorsal fin is slightly larger. The second dorsal fin is found slightly in front of the anal fin, which is about half the size of the second dorsal fin. There are two tail lobes; the lower lobe is rounder and shorter than the upper lobe and the rear lobe has a deep notch near the tip. This species has a tapering, blunt snout and a spiracle behind each narrow eye.

The species of  genus Mustelus have flat and blunt dentition. It distinguishes to other shark species that have sharp and blade-like teeth. The small teeth of the smooth dogfish are of similar size in the upper and lower jaw. They are not symmetrical in shape with a rounded apex. They have between 8-10 rows of teeth used to crush and grind their food rather teeth used to bite and tear as in other shark species. The differences between  Smooth dogfish shark and Spiny dogfish  are by the presence of a single spine in front of each of the two dorsal fins of the Spiny dogfish.

Smooth dogfish shark varies in color from gray to brown with a yellow-gray to white ventral side. This species can change its color by contracting its melanophores to blend into its surroundings. Smooth dogfish can change their color from dark to light, to camouflage themselves from predators. Smooth dogfish are born with a first dorsal fin that is dusky gray in color at the edges. The apex of the second dorsal fin is also dusky gray and has a white rear edge with a white-edged tail fin. These markings fade by the time the shark is about two feet in length.

Smooth dogfish feeds on large crustaceans, including crabs and lobsters, and on shrimp, small fish, and mollusks. They are preyed on by other shark species including: Sandbar Sharks, Great White Sharks, Dusky Shark, Blacktip Shark and Great Hammerhead Shark. In certain areas, the flesh of Smooth dogfish is marketed as fresh or dried salted for human consumption. Smooth dogfish is caught commercially and as a game fish. It is probably considered by catch in most fisheries. Smooth dogfish is often used as a laboratory animal and in public display at aquariums.

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