|Similar Largespine velvet dogfish, Scymnodalatias, Plunket shark, Western highfin spurdog, Rasptooth dogfish|
The southern sleeper shark or Whitley's sleeper shark (Somniosus antarcticus) is a deepwater benthopelagic sleeper shark of the family Somniosidae found in the southern Atlantic, Indian, and Pacific oceans. It is known from depths of 400 to 1,100 m. Its length is up to 4.4 m (14 ft). It feeds primarily on cephalopods, especially the colossal squid, and fish; its stomach contents also less commonly contain remains of marine mammals and birds. Based on its generally sluggish nature and the speed of its prey, it is thought to be an ambush predator. A 3.6-m-long female caught off the coast of Chile had a whole southern right whale dolphin in its stomach. This dogfish is sometimes taken as bycatch in the orange roughy and Patagonian toothfish fisheries; whether this poses a threat to the species is currently unknown.
This fish was formerly sometimes viewed as conspecific with either the Greenland shark, Somniosus microcephalus, or the Pacific sleeper shark, Somniosus pacifius. However, it was shown in 2004 to be a distinct species.