This shark’s unusual name is derived from its slow, almost effortless movement through the deep, cold waters of its habitat. Although the fish appeared sluggish to early observers, the Pacific Sleeper Shark is actually capable of extreme bursts of speed when pursuing prey or avoiding danger. The shark’s ability to pass through the water will little movement or hydrodynamic noise (underwater noise created by movement or turbulence) is a unique adaptation that makes it an effective predator of octopus, rockfish, shrimp, crab and snails. It has a cylindrical body with two dorsal fins of approximately the same size. The shark is usually dark gray or black in color. It grows up to 14 feet (4.2 m) in length.
Although studied in Alaskan waters, there is little data on them from the Oregon coast. The Sleeper Shark has some habits which may indicate it is an opportunistic feeder. The shark will congregate around Stellar Sea Lion haul-outs (areas where the animal goes ashore) and follow the migration routes of the Gray Whale. Since the Sleeper Shark does not actively attack either of these animals, it may be scavenging on the remains of both sea lions and whales that died from other causes.
The Pacific Sleeper Shark can be found in deep cold waters of the continental shelf (up to 6,600 feet or 2,000 m) all along the west coast of North America. They range as far north as Alaska south to Baja California.
Due to limited data, the Sleeper Shark’s numbers worldwide are unknown.