Dusky smooth-hound time to induce tonic immobility in smooth dogfish was 32.5 seconds. The mean duration of the tonic immobility was 61.9 seconds. Sharks that had the “limp” response also exhibited tonic immobility. The “limp” response is a criterion for the onset of tonic immobility. Dusky smooth-hound The dusky smooth-hound ("Mustelus canis"), also called the smooth dogfish or the dog shark, is a species of houndshark in the family Triakidae. This shark is an olive grey or brown in color, and may have shades of yellow or grayish white. Females live to 16 years and males have a lifespan of 10 years.
Narrownose smooth-hound Narrownose smooth-hound The narrownose smooth-hound ("Mustelus schmitti") is a houndshark of the family Triakidae. It is found on the continental shelves of the subtropical southwest Atlantic, from southern Brazil to northern Argentina, between latitudes 30° S and 44° S, at depths between 60 m to 195 m. It can reach a length of 74 centimeters. Narrownose smooth-hounds feed on crabs and probably other crustaceans, and presumably small fishes. Narrownose smooth-hounds are also caught and utilized for human consumption. The reproduction of this houndshark is Ovoviviparous, with 2 to 7 pups per litter, and a birth length of about 26 cm.