The leopard seal, Hydrurga leptonyx, is a formidable predator in the Southern Ocean. As the second-largest seal species in the Antarctic, it occupies a position near the top of the food chain. Its powerful build and hunting style lead to questions about whether this apex predator preys upon sharks.
Documented Instances of Shark Predation
Scientific observation confirms that leopard seals occasionally prey on sharks, a finding that places them in an exclusive group of marine mammals. This behavior is not a regular occurrence throughout their Antarctic range. The most compelling evidence comes from vagrant leopard seals sighted along the coasts of New Zealand, outside their typical polar habitat.
Analysis of scat and physical wounds provided concrete evidence of this predatory relationship. Researchers identified remains of cartilaginous fish, known as chondrichthyans, in the seals’ feces. Specific prey species include elephantfish (Callorhinchus milii), spiny dogfish (Squalus acanthias), and ghost sharks (Hydrolagus spp.).
The seals also bore scars and wounds, with some individuals having shark spines embedded in their faces, indicating an active and dangerous struggle during the hunt. For a small number of leopard seals in the New Zealand area, this predation appears to be a consistent part of their foraging behavior. In this population, shark remains were found in 7.1% of scat samples and accounted for 23.1% of observed predation events.
The Primary Leopard Seal Menu
While consuming sharks is a notable discovery, it represents a minor, opportunistic component of the leopard seal’s overall diet. The foundation of its menu, particularly for younger seals, is Antarctic krill, Euphausia superba. Krill can constitute a significant portion of the seal’s food intake, sometimes making up more than half of its diet by volume.
As the seals mature, their diet shifts to include larger, more substantial prey. Penguins are a frequently targeted food source, including Adélie, Emperor, and Chinstrap penguins. The seals patrol the ice edges, waiting to ambush the birds as they enter or exit the water, often violently shaking them.
Leopard seals also prey on other pinnipeds, specializing in the pups of other seal species. This includes vulnerable young crabeater seals and fur seals, which are less capable of defending themselves. This diverse range, from krill to other seals, confirms the leopard seal’s standing as a highly adaptable generalist predator.
Specialized Hunting Adaptations and Habitat
The leopard seal’s ability to hunt a wide array of prey, including the occasional shark, is linked to its specialized physical characteristics. These seals are massive, with females reaching lengths of up to 3.5 meters and weights exceeding 500 kilograms. This size is combined with a powerful, streamlined body that allows for high agility and speed in the water.
Their dentition is uniquely adapted for a dual feeding strategy. The front of the jaw features long, sharp canine teeth, designed for piercing and tearing the flesh of large prey like penguins and seals. These powerful jaws deliver the force needed to subdue struggling victims, including those with defensive spines.
The seal’s posterior teeth are equally specialized, featuring trident-shaped molars that interlock. These molars act as a sieve, allowing the seal to filter water and strain out vast quantities of krill, similar to the feeding mechanism of baleen whales. The primary habitat is the circumpolar pack ice of the Antarctic, and their predatory behavior is dictated by the seasonal movements and availability of prey in these frigid Southern Ocean waters.