Speckled smooth-hound seabed on the continental shelf at depths of between . Reports of this fish occurring in the Atlantic Ocean off the coast of Argentina are thought to be erroneous, and are likely to refer to the narrownose smooth-hound ("Mustelus schmitti"), another shark that is speckled with white spots. The speckled smooth-hound is ovoviviparous with eggs that develop within the female and hatch into juvenile fish which are about at birth. Litter sizes are typically seven. Along with the humpback smooth-hound ("Mustelus whitneyi") and the spotted houndshark ("Triakis maculata"), this fish is known to local fisheries as "tollo" and is caught
Dusky smooth-hound the lower is smaller and rounder and the upper has a deep notch. They do not have any fin spines, unlike the spiny dogfish. They have a tapering, blunt snout. They can be gray to brown and their undersides can be white to yellowish gray. Smooth dogfish have the ability to change colors using melanophores to help them camouflage. Newborns have lighter gray edges on their fins and have tail fins edged in white. On average, smooth dogfish are about 48 in long, but can reach up to 5 ft. They have an inter-dorsal ridge. One main characteristic of elasmobranch