Elephant Seal

## Description

The northern elephant seal (Mirounga angustirostris ) is one of two species of elephant seal (the other is the southern elephant seal). It is a member of the family Phocidae (true seals). Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. Sexual dimorphism in size is great. Correspondingly, the mating system is highly polygynous; a successful male is able to impregnate up to 50 females in one season.

## Appearance

Elephant seals are large seals that live in the ocean, of which there are two species, both of which were hunted almost to extinction by the close of the 19th century. The numbers have recovered since. One is the Northern elephant seal and the other is the Southern elephant seal, the latter being larger than its northern relative. These animals are huge when compared with other pinnipeds. They get their name from the adult male's large proboscis, which looks like an elephant's trunk. The Southern elephant seal has a coat that is light to dark silvery-gray or brown, while the Northern elephant seal is colored dark brown to light tan. Their ears are small holes.

## Distribution

The Northern elephant seal inhabits the Pacific coast of Mexico, the U.S., and Canada. Race Rocks is the most northerly breeding area on the Pacific Coast, at the southern end of Vancouver Island's Strait of Juan de Fuca. The seals inhabit gravel or sandy beaches, far away from human activity, as their preferred places for breeding. When at sea, males tend to feed over continental shelves, while females prefer deeper open water. Southern elephant seals are found on big and small islands along the coasts of South Africa, New Zealand, Argentina, and Chile. During the breeding season, these seals are generally found on rocky terrain and beaches, and sometimes on snow and ice. They live in the open ocean during the non-breeding season.

## Behavior

Elephant seals spend up to 80% of their lives in the ocean and usually only come to land to give birth, breed, and molt. Most of the time they are moving about, migrating while foraging for food. Both males and females spend time at sea but their feeding habits and migration routes differ: males will follow a route that is more consistent, while females will vary their route in pursuit of prey. Female elephant seals forage in the open ocean, while male elephant seals forage along the continental shelf. Males usually dive straight down to the ocean floor and stay at the bottom foraging for benthic prey. While hunting in the dark depths, elephant seals seem to locate their prey at least partly by vision; the bioluminescence of some prey animals can facilitate their capture. Elephant seals do not have a developed system of echolocation in the manner of cetaceans, but their vibrissae, which are sensitive to vibrations, are assumed to play a role in search of food. Elephant seals when in the water are solitary in nature, but they come together on the shore during mating season. There is a social hierarchy during the mating season, but males are less aggressive with each other when they come to land for molting. This molting process takes up to a month to complete. When it comes time to molt, they will haul out on land to shed their outer layer, and will not consume any food during this time. The females and juveniles will molt first, followed by the sub-adult males, and finally the large mature males.

## Diet

Elephant seals are carnivores (piscivores) and their favorite foods are skates, rays, squid, octopuses, eels, small sharks, and large fish.

## Reproduction

Elephant seals are polygynous, and each dominant male is in control of mating access to a group of females. Dominant males arrive at potential breeding sites in spring and fast to ensure that they can mate with as many females as possible. Males use fighting, vocal noises, and different positions to determine who will be deemed the dominant male. They display their dominance by showing their noses, making loud vocalizations, and altering their postures. They fight each other by raising themselves and ramming each other with their chests and teeth. When females arrive, the dominating males have already selected their territory on the beach. Females cluster in groups called harems, which could consist of up to 50 females surrounding one alpha male. Outside of these groups, a beta bull is normally roaming around on the beach helping the alpha by preventing other males from accessing the females. Northern elephant seals haul out for birthing and breeding from December to March, while their southern relatives breed in August to late November. After a gestation period of 7-9 months for Southern elephant seals and 10-12 months for Northern elephant seals, a single pup is born. Pups are generally weaned at around 20-27 days, when the female will remain with her new pup, giving it large quantities of fatty, rich milk, relying on the thick blubber of her body for sustenance. Elephant seals gain reproductive maturity from 2 to 10 years of age.

## Population

### Population threats

Northern elephant seals suffer today from a significant absence of genetic diversity in their populations, the result of drastic reductions in the past. The result of this may be that the northern elephant seal is ill-equipped to cope with any changes in its environment. The main threat to these animals is large-scale fisheries, potentially competing with them for their preferred prey.

### Population number

According to the IUCN Red List, the population size of Northern elephant seals in 2010 was estimated at between 210,000 and 239,000 animals. There is no recent comprehensive estimate of Southern elephant seal abundance. In the 1990s, the population of Southern elephant seals was estimated to be between 664,000 and 740,000 animals. Elephant seals are currently classified as Least Concern (LC) on the IUCN Red List of threatened species.

## Fun Facts for Kids

Southern elephant seals are the deepest diving air-breathing non-cetaceans and have been recorded at a maximum of 2,388 m (7,835 ft) in depth.

When foraging, the dive depth of the Northern elephant seal averages 500 to 600 m (1,640 - 1,970 ft), but it is able to dive to as much as 1,500 m (4,920 ft) and stay underwater for over 1 hour.

Seals have many whiskers, called “vibrissae”, which help them locate prey in deep or murky water. Though they appear to have no ears, in fact, they have small ear holes which function well when they are both in water and on land.

The bodies of these seals contain a lot of blood, which helps them to stay deep down in the ocean for a much longer time because their blood holds a high volume of oxygen which helps them when they dive.

Despite their massive size, elephant seals are not slow. On the contrary, they are very good swimmers. If you see an elephant seal coming towards you from a distance, run quickly to safety, as on sand dunes they can move more quickly than humans.