Dusky smooth-hound fishes is their ability to continually replace the teeth in their upper and lower jaws. Smooth dogfish differ from other sharks because of their 10 rows of flat, blunt teeth. The teeth in the upper and lower jaws are similar in size and are asymmetrical with rounded cusps. These teeth are used to crush and grind food, rather than bite it. Their unique dentition is important for their crustacean-based diet. In smooth dogfish, tooth replacement is related to body growth. They grow about 10 cm per every six rows of teeth replaced. That is an increase of 0.03 mm per
Common smooth-hound Common smooth-hound The common smooth-hound ("Mustelus mustelus") is a houndshark of the family Triakidae. It is found in the eastern Atlantic Ocean from the British Isles to South Africa, and in the Mediterranean Sea, Madeira, and the Canary Islands at depths ranging from 5 m to 625 m (although they usually stay at depths between 5-50m). While they can grow to 200 cm, their usual maximum size is 150 cm. They commonly grow to 100–120 cm with a birth length around 35 cm. The reproduction of commons smooth-hounds is viviparous. The common smooth-hound has a grey-brown back and is white