South American sea lion

The South American sea lion (Otaria byronia, also known as Otaria flavescens) has a pronounced sexual dimorphism that easily distinguishes males and females: males have a ‘mane’ around their necks, which stands out in reddish colour against their dark brown fur, and can weigh between twice and three times as much as females. In addition to the distinctive fur of the males, the sea lion is so named because it communicates with sounds similar to roaring or barking.

This species inhabits the South American coastline both in the Pacific Ocean, in the Galapagos Islands and Isla de la Plata in Ecuador and the coasts of Peru and Chile; and in the Atlantic Ocean, in Uruguay, Argentina and the British archipelagos of Malvinas and South Sandwich Islands.

The South American sea lion lives in small colonies of about fifteen members - the male, four to ten females and some juveniles, pups of both - for most of the year. However, between December and February, during the austral summer when breeding and reproduction take place, thousands of sea lions gather in sheltered areas where females arrive just three days before giving birth to a single pup after a year-long gestation. The females stay on land for a week, nursing the pups, before returning to the sea to feed again. During this period, usually six days after calving, they come into heat again, causing the males to fight for dominance over the females. Once the pups have left the breeding area, they are cared for for up to ten months.

Both the sea lion and the seal are pinniped species, that is, carnivorous mammals adapted to marine life, characterized by a fish-like body; wide, fin-shaped hind legs and front legs with interdigital membranes, suitable for swimming and diving at high speed; and skin covered with dense fur and abundant fatty tissue underneath to protect their bodies from the cold, store energy and help them float in the sea.

Although sea lions bear a strong physical resemblance to seals, among the characteristics that differentiate them are the following:

• Sea lions have small, somewhat pointed ears, while seals lack an external ear and only two holes are visible on either side of the head.
• Sea lions move on land using their four flippers and can even run, while seals drag their bodies and propel themselves only with their hind legs.
• Sea lions have nails on their hind flippers, which, although they have no function, are maintained from their ancestors more adapted to life on land.