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
Hound trailing the popularity of the sport led to the establishment of the "Hound Trailing Association" in 1906, this was followed by the Border Hound Trailing Association in 1933 and later the Yorkshire Hound Trailing Association and associations in County Cork and County Kerry. Trail hounds have evolved into a distinct breed or type of hound specifically bred for performance alone, they are sleek, hard muscled hounds with almost whippet like bodies. Trail hounds descend from the Fell hounds, foxhounds found in the north of England. In his "Foxes, foxhounds and fox-hunting", Richard Clapham stated "fell hounds trace their origin back to