Antarctic sleeper shark reveals extreme survival traits

Footage captured by an international research team operating in the Southern Ocean shows a large, slow-moving shark cruising at depths where water temperatures hover near freezing. Researchers believe the animal belongs to the sleeper shark family, a group already known for exceptional longevity and resilience. The discovery marks one of the clearest records of such a shark in Antarctic seas, expanding the known range of a species previously associated mainly with the North Pacific and Arctic regions.

Sleeper sharks, which include the Greenland shark and the Pacific sleeper shark, have long intrigued marine biologists. The Greenland shark in particular has been dated, through radiocarbon analysis of eye tissue, to lifespans exceeding 250 years, with some estimates suggesting individuals may approach four centuries. These findings, published in peer-reviewed scientific journals over the past decade, positioned sleeper sharks among the longest-living vertebrates on the planet.

The Antarctic sighting reinforces the group’s reputation for thriving in extreme cold. Southern Ocean temperatures often sit between –1°C and 2°C, conditions that would be lethal to many large predators. Sleeper sharks cope through a combination of slow metabolism and specialised biochemistry. High concentrations of urea and trimethylamine N-oxide in their tissues prevent proteins from destabilising in icy water, allowing vital physiological processes to continue at temperatures close to the freezing point of seawater.

Scientists involved in the expedition described the shark as moving with characteristic lethargy, a trait linked to energy conservation. This slow pace, far from a weakness, appears central to its survival strategy. By minimising exertion and feeding opportunistically on fish, squid and carrion, sleeper sharks can sustain themselves in ecosystems where prey can be sparse and seasonal.

Marine ecologists say the Antarctic observation raises important questions about how these animals disperse across vast ocean basins. Genetic studies conducted on Pacific and Greenland sleeper populations have previously indicated wide-ranging movements at depth, with some individuals travelling thousands of kilometres. Ocean currents, including the Antarctic Circumpolar Current, may facilitate such dispersal, linking polar regions more closely than once assumed.

Climate change adds urgency to understanding these patterns. Polar seas are warming at uneven rates, with parts of the Southern Ocean experiencing measurable shifts in temperature and sea-ice cover. Long-lived species such as sleeper sharks, which mature slowly and reproduce infrequently, may be particularly vulnerable to rapid environmental change. Researchers caution that while the species has endured glacial cycles over millennia, the pace of current warming presents unfamiliar challenges.

At the same time, the presence of a top predator in Antarctic depths highlights the ecological complexity of waters often portrayed as barren. Sleeper sharks occupy a high trophic level, influencing food webs that include toothfish, cephalopods and other cold-adapted species. Their movements may intersect with commercial fisheries operating under international management regimes, including those targeting Antarctic toothfish. Scientists say better data on sleeper shark distribution will be essential for informed conservation decisions.

Technological advances have played a decisive role in bringing these animals into view. Deep-sea cameras mounted on remotely operated vehicles and baited landers now allow researchers to document species that once escaped detection. Decades ago, knowledge of sleeper sharks relied largely on accidental catches or fragmentary observations. High-definition imagery from Antarctic missions now provides behavioural context, revealing posture, swimming patterns and interactions with the seabed.

Biologists emphasise that much about sleeper sharks remains unknown. Precise growth rates, reproductive cycles and population sizes are still subjects of active study. The extraordinary longevity recorded in Greenland sharks, confirmed through radiocarbon dating techniques, challenges conventional assumptions about vertebrate ageing. Scientists are investigating whether similar life histories apply to Pacific or Antarctic-dwelling relatives.

Physiological research also points to potential biomedical insights. The compounds that stabilise proteins in frigid conditions are of interest to researchers studying cellular preservation and cryobiology. Although such applications remain exploratory, the biochemical adaptations of sleeper sharks continue to attract interdisciplinary attention.

Conservation groups note that deep-sea species often face threats that are poorly understood because of limited monitoring. Bycatch in longline fisheries, habitat disturbance from seabed activities and shifting ocean chemistry could affect sleeper shark populations long before comprehensive assessments are available. International agreements governing Antarctic waters include precautionary principles, yet scientists argue that baseline data are still sparse.