Fish
Pacific Sleeper Shark
Somniosus pacificus · also called sleeper shark
Moving with a slow, deliberate grace that seems mismatched to its diet, a Pacific sleeper shark has turned up with giant squid remains in its stomach more than once, a puzzle given how much faster that prey should be able to escape.
Overview
The Pacific sleeper shark, Somniosus pacificus, is a slow-moving carnivore native to deep, cold ocean habitat across the North Pacific Ocean. Its close kinship with the Greenland shark, energy-conserving sluggish swimming style, and puzzling giant squid prey records make it one of the more mysterious large predators found anywhere in the deep sea.
A slow hunter with a fast prey mystery
The presence of giant squid remains inside a shark too slow to plausibly outswim one raises real questions researchers have yet to fully answer, whether through scavenging opportunistic finds or hunting techniques not yet observed.
Status
Near Threatened, with populations declining in parts of the North Pacific due to bycatch and limited survey data.
Pacific Sleeper Shark: common questions
Why is the Pacific sleeper shark found with giant squid remains in its stomach?
This species has been documented with giant squid remains in its stomach, a puzzling find since giant squid are generally capable of swimming much faster than this slow-moving shark, suggesting it may scavenge dead or dying squid rather than actively hunting them.
Is the Pacific sleeper shark related to the Greenland shark?
Yes, this species belongs to the same genus as the Greenland shark, sharing a similarly slow, sluggish swimming style suited to conserving energy in the cold deep water both species inhabit.
Why does the Pacific sleeper shark move so slowly?
This species swims with remarkably slow, deliberate movements, a pace that conserves energy in its cold, food-scarce deep-water habitat and gives the genus its common "sleeper shark" name.
Why is so little known about the Pacific sleeper shark?
This species remains relatively poorly studied, with significant gaps in knowledge about its behaviour, lifespan, and detailed population size, largely due to the difficulty of studying an animal that lives at such extreme depth.