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
Slender smooth-hound pups, one per uterus. The International Union for Conservation of Nature (IUCN) has assessed the slender smooth-hound as Least Concern; it is taken as fishery bycatch but not in great numbers, and furthermore large portions of its range see minimal fishing activity. The first known specimen of the slender smooth-hound was a long adult male collected by the trawler "Maimai" in December 1953, at a depth of off Cape Palliser on New Zealand's North Island. It was preserved by the crew as a curiosity and given to ichthyologist Jack Garrick, who described it in a 1954 issue of the scientific