Smallest marine mammal

The smallest sea-dwelling mammal is the rare and little-known marine otter (Lontra felina), aka sea cat, native largely to the Pacific coast of South America, although its range may also edge around Cape Horn into the Atlantic waters of southern Argentina. Adults measure between 87 and 115 centimetres (2 feet 10 inches–3 feet 9 inches) in total length and typically weigh no more than 5 kilograms (11 pounds).

Marine otters spend the majority of their time in the sea, however do occasionally venture onto rocky shores or outcroppings, particularly during the breeding season.

This species spends as much as 70% of their time foraging for food such as crustaceans, molluscs and fish (and occasionally birds and small mammals). They are typically successful in around 26–32% of their dives, during which they can reach depths of 40 m (130 ft).

The marine otter is currently listed as Endangered by the IUCN, with populations hugely depleted after many decades of being hunted for their pelts. The species is now protected under law in its home range of Peru, Chile and Argentina.

The next smallest marine mammal is the sea otter (Enhydra lutris), found in the cold waters off western North America, eastern Russia and northern Japan. Full-grown males average 1.4 metres (4 feet 7 inches) and weigh between 23 and 45 kilograms (50-100 pounds), while adult females attain a slightly shorter length of 1.2 metres (4 feet) and typically weigh between 16 and 27 kilograms (35-60 pounds).