Name: Northern Elephant Seal (Mirounga angustirostris), Southern Elephant Seal (Mirounga leonine)
Length: Up to 6,2 metres
Weight: Up to 4,000 kg
Location: Northern – West coast of North America, offshore islands, Southern – Antarctic and sub-Antarctic waters
Conservation status: Least Concern
Diet: Squid, fish, sharks, rays, ratfish, molluscs, crustaceans, krill, algae
Appearance: Black or reddish-brown
How do Elephant Seals hunt?
The Northern Elephant Seals are nocturnal hunters, diving between 300 and 800 metres. Males tend to hunt along the continental shelf, foraging on the ocean’s floor, while females hunt more in the open ocean. Not having echolocation, seals have to use sight (perhaps added by the luminous nature of some of their prey) and their vibrissae (whiskers) to sense nearby movement. Males return to the same areas every year to hunt, while females are more random. Southern Elephant Seals dive from 400 to 1,000 metres for up to 20 minutes at time. The deepest recorded dive doubled the average, going to a little over 2,100 metres. To stay underwater for so long they have to exhale before diving to get the gases out of their bodies or they would suffer from the bends, the same fate awaiting divers who ignore the effect of water pressure on the gases in their bodies.
To maintain oxygen levels, the Elephant Seals have a tremendous amount of blood to store the oxygen in hemoglobin, as well as storing it in their muscles. The seals in fact have twice the volume of blood of land mammals of the same size, and the blood contains 50% more hemoglobin. They also slow their heartbeats from the usual 50-120 beats a minute to 5-15 beats, and they restrict their blood flow to the most vital organs, all of which allows them to greatly slow their oxygen consumption.
Do Elephant Seals socialize?
Male Elephant Seals fight for dominance over harems while on land, and continuously have to fight to maintain their rank. The male may have to stay on land to defend his territory for months at a time, meaning he can’t leave to hunt. Battling males use both their weight and their teeth against each other. Fatalities are rare, but the fights can leave the bulls with severe cuts. Elephant Seals range solo while at sea.
How fast can Elephant Seals go?
On land they can hump their way along the ground at a max of about 5 km an hour. While swimming they move at speeds ranging from 5 to 10 km/h.
Elephant Seal Mating Rituals
Female Elephant Seals reach sexual maturity as early as 3 years of age; males reach sexual maturity at 6 but usually don’t have enough muscle to become a dominant bull until they’re about 9. Elephant Seal bulls arrive at the mating grounds (beaches) in December through January and engage in battles for dominance. They then establish harems of the arriving females, the harems having between 30 and 100 females, depending on the social rank of the male. Males who failed in the battles will wait around the edges of the seal colony, trying to sneak in little quickie mating sessions with the females on the fringes before the dominant bull chases them off. The highest ranking males may father up to 500 pups during their lifetime.
The females arrive already pregnant from the previous mating season 11 months ago. The pups are born about 5 days after the females’ arrival at the rookery. The babies are around 32 kg, and will nurse for about 26 days after birth. Mating occurs during the last few days of the nursing period. The pups are abruptly weaned off their mother’s milk when the mother heads back to sea. The pups have now quadrupled their weight up to approximately 120 kg. They’ll lose about 1/3rd of this weight in the next 8 weeks as they stay behind near the rookery, learning how to swim.
How long do Elephant Seals live?
Female Elephant Seals live to be about 20-25 years old, with males generally reaching around 15 years of age.
How many Elephant Seals are there today?
Once hunted to near-extinction, conservation efforts have brought the population back to a rough worldwide estimate of 910,000, which breaks down as:
- Northern – 170,000
- Southern – 740,000
Do Elephant Seals have any predators?
Seal pup are prey for sharks, leopard seals, and sea lions, while both pups and adults can be attacked by Killer Whales.
7 Illuminating Elephant Seal Facts
- The Northern Elephant Seal is the only mammal known to make a migration twice a year.
- They can travel up to 33,800 km in a single year, which is the longest known migration for any mammal.
- Elephant Seals get their name from their distinct proboscis (nose) which resembles an elephant’s trunk. The “trunk” serves two purposes. Males use the proboscis to generate loud roars to fend off other males. Both males and females use it as a rebreather of sorts – it reabsorbs moisture when the seals exhale, which is important during their fasts during mating season.
- Elephant Seals and Monk Seals are the only seals that molt – they shed their outer layer of skin. They need to shed skin just like humans do, but to do so in an ongoing process like humans requires more blood circulation to the skin. This would mean seals would have to pass their blood outside their layer of blubber, rapidly cooling the blood.
- Males form a shield of keratinized skin on their chests to protect them when fighting with other males.
- Elephant Seals spend almost 90% of their lives in the water. Despite their huge colonies on land, they’re loners while at sea.
- Males can weigh up to 10 times what the females weigh, which is the greatest disparity between the sexes of any mammal.