The great white shark has the most fearsome reputation of all sharks. But it might not be the biggest of the predator sharks. That honor might go to the Pacific sleeper shark. The biggest one ever seen appeared to be about 23 feet long—longer than the biggest great white.

The Pacific sleeper is found mainly in cold waters around the rim of the northern Pacific Ocean. But some have been seen in warmer waters close to the equator.

The shark got its name because it was thought to spend most of its time near the bottom, waiting for prey to swim by—a “sleepy” sort of behavior. But at least one study found otherwise. The sharks were found to move up and down through the water column, from the bottom to near the surface. And some covered as much as three or four miles a day.

Pacific sleepers will eat just about anything. They prefer fish that dwell on the bottom, along with giant octopus. But their stomach contents also show other types of fish, snails, sea lions, and other prey. They might have hunted down some of them, and gobbled the already dead remains of others.

The shark hasn’t been studied that much. The largest one ever caught was about 14 feet long and weighed half a ton. But video cameras caught one that was estimated at 23 feet.

Pacific sleepers probably grow slowly and have a low reproduction rate. So they could be threatened by overfishing, mostly as bycatch—draining the population of what might be the largest of all predator sharks.