Eumetopias Neophoca Otaria Phocarctos Zalophus Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly.

Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight (about 6.8–15.9 kg (15–35 lb)) at a single feeding.

This division was based on the most prominent common feature shared by the fur seals and absent in the sea lions, namely the dense underfur characteristic of the former.

[8] This is consistent with the fossil record which suggests that this genus diverged from the line leading to the remaining fur seals and sea lions about 6 million years ago (mya).

[8] Arctocephalus is characterized by ancestral character states such as dense underfur and the presence of double rooted cheek teeth and is thus thought to represent the most "primitive" line.

It was from this basal line that both the sea lions and the remaining fur seal genus, Callorhinus, are thought to have diverged.

Physiology dictates thermoregulation, osmoregulation, reproduction, metabolic rate, and many other aspects of sea lion ecology including but not limited to their ability to dive to great depths.

One of the ways sea lions deal with the extreme pressures is by limiting the amount of gas exchange that occurs when diving.

[10] Another way sea lions mitigate the oxygen obtained at the surface in dives is to reduce digestion rate.

After a sea lion returns from a long dive, CO2 is not expired as fast as oxygen is replenished in the blood, due to the unloading complications with CO2.

[14] New Zealand sea lion pups (Phocarctos hookeri) were also affected in really early ages by hookworms (Uncinaria).

These toxins are ingested by sardines and other fish which are then eaten by the sea lions, causing neurological damage and diseases such as epilepsy.

[17] In New Zealand sea lions, north-to south gradients driven by temperature differences were shown to be key factors in the prey mix.

[20] Sea lions, with three groups of pinnipeds, have multiple breeding methods and habits over their families but they remain relatively universal.

Otariids, or eared sea lions, raise their young, mate, and rest in more earthly land or ice habitats.

[21] Steller sea lions, living an average of 15 to 20 years, begin their breeding season when adult males establish territories along the rookeries in early May.

[22] Otaria flavescens (South American sea lion) lives along the Chilean coast with a population estimate of 165,000.

According to the most recent surveys in northern and southern Chile the sealing period of the middle twentieth century that left a significant decline in sea lion population is recovering.

Studies of South American sea lions and other otariids document maximum population on land during early afternoon, potentially due to haul-out during high air temperatures.

Adult and subadult males do not show clear annual patterns, maximum abundance being found from October to January.

[24] Although sealing has been put to a halt, in many countries, such as Uruguay, the sea lion population continues to decline because of the drastic effects humans have on their ecosystems.

[24] As a result, South American sea lions have been foraging at higher tropical latitudes than they did prior to human exploitation.

[25] When fishermen are successful at their job, they greatly reduce the sea lion's food source, which in turn endangers the species.

[31] Females need to move inland as a way to protect their pups, so roads, fences, residential areas, and private lands can inhibit their dispersal and breeding success.

[33] As one of the world's rarest sea lions, and an endangered and endemic species, efforts are being made to facilitate coexistence between them and humans.

[26] In a highly unusual attack in 2007 in Western Australia, a sea lion leapt from the water and seriously mauled a 13-year-old girl surfing behind a speedboat.

An Australian marine biologist suggested that the sea lion may have viewed the girl "like a rag doll toy" to be played with.

The child was sitting on a pier side in British Columbia while tourists were illegally feeding the sea lions when the incident took place.

One such notable instance of this is when Kevin Hines jumped off the Golden Gate Bridge in a suicide attempt and was helped to stay afloat by a sea lion until he was rescued by the Coast Guard.

[26] One of the main sites to view sea lions is in the Carnac Island Nature Reserve near Perth in Western Australia.