Members of the suborder Pinnipedia, seals and sea lions are characterized by paddle-like flippers on a pair of limbs. Most pinnipeds are found in boreal or polar regions and are the most important predators in many high latitude areas, feeding primarily on fish and squid. Seals and sea lions catch their prey during extended dives of up to 25 minutes at depths of 2,625 ft (800 m) or more. Pinniped biologists are interested in the physiological changes these animals undergo during their dives. Known as mammalian dive response, a combination of reduced heart rate and a lowered core body temperature enables these warm-blooded animals to complete such dives.

Seals and sea lions must return to beaches and ice floes each year to give birth. Here they raise their pups in large congregations known as colonies. In some species the larger, more aggressive males will form...