Marine mammals of Argentina

There are two groups of mammals adapted to the marine environment in Argentina: the Pinnipeds and the Cetaceans.

Pinnipedia: Two of the three extant groups are present in Argentina: the sea lions and the seals (including the largest one, the Elephant Seal). These two groups are morphologically distinguishable by the presence of external ears and quadrupedal locomotion in the sea lions, and the lack of external ears and crawling locomotion in the seals. The third group includes the Northern Hemisphere walruses.
Pinnipeds inhabit most of the coasts of the world, being more frequent in polar and temperate waters. They are animals with elongated hydrodynamic bodies, with limbs transformed into fins, and a thick layer of subcutaneous fat that serves them as thermal insulator. They feed on marine animals such as crustaceans, mollusks, fish, aquatic birds, and even other pinnipeds. All pinnipeds need to return to land for reproduction, so the specific habitat of these mammals can be considered to be semi-aquatic.

Cetacea: They are exclusively aquatic mammals, with fusiform bodies, paddle-like forelimbs without fingers or nails, hind limbs absent, and a transverse caudal fin. Like the pinnipeds, cetaceans also have a thick layer of subcutaneous fat that in some species can reach up to 35 centimeters thick. Some cetaceans have teeth (Odontoceti) and their diet includes large animals such as squids, fish, aquatic birds, pinnipeds, and others. This group includes dolphins, porpoises and killer whales. Other cetaceans (Mysticeti) do not have teeth but «baleens», which they use to filter very small marine organisms such as krill (Euphausia superba). Among them, we find the different species of whales.