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
Humpback smooth-hound the three species it is the humpback smooth-hound that is the main target of the tollo fishery in Peru. Landings averaging 11,000 tons of tollo per year were made in that country between 1965 and 1989, but quantities caught diminished thereafter. A minimum size requirement of was set in 2001 but was pitched so low as to have limited conservation effect. The International Union for Conservation of Nature (IUCN) has rated the status of the humpback smooth-hound as being "vulnerable" and considers more should be done to publicise and enforce the size limit. Humpback smooth-hound The humpback smooth-hound ("Mustelus whitneyi")