| Home: Special status species: Northern elephant seal: Natural History |
SPECIAL STATUS SPECIES: NORTHERN ELEPHANT SEAL (Mirounga angustirostris)
NATURAL HISTORY |
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| General |
| Taxonomy: |
Order
Carnivora, Suborder Pinnipedia, Family Phocidae.
The genus Mirounga (elephant seals) contains
two species; Mirounga leonine occurs
only in the southern hemisphere and Mirounga
angustirostris
occurs only in the northern hemisphere.
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| Appearance: |
Like all
members of Family Phocidae, this species is lacking
external ear flaps (pinnae). The hind-flippers are
used for underwater propulsion and are always extended
behind the body. This species cannot walk on land,
but instead scoots along the ground on its belly.
Males are much larger than females. Males average
3.82 m and 1,704 kg and females average 2.65 m and
489 kg.11
Both sexes are covered with short, coarse gray, tan
or brown fur. They have a very thick layer of blubber.
As males mature they develop a proboscis (an elongated
nose) and a chest shield of pinkish keratinized skin
that helps to protect them from injury during territorial
battles with other males. |
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| Feeding Behavior |
| Overview: |
This species dives
deeper and longer than most species of marine mammals.
When at sea, they are submerged 83-92% of the time.6
Females range widely over deep water foraging on vertically
migrating, pelagic prey while males forage on benthic
prey along the continental margin.3
While on land during breeding and molting season,
northern elephant seals fast and lose on average 36%
of their body weight.11 |
| Prey Items: |
Females:
Mesopelagic fish, squid, octopus; Males: benthic sharks,
rays, skates, rockfish, lamprey, squid, octopus12 |
| Method of
Capture: |
This species
dives to catch its prey. Dives typically last 20-30
minutes and go routinely to depths of 300-500 m.6
However, this species has been recorded diving to
1,500 m and can remain submerged for at least 68 min.6
Elephant seals use their large eyes and the bioluminescence
of some prey, such as octopus and squid, to find food
at depth where no sunlight penetrates. In addition,
they may use their sensitive whiskers to “feel”
for benthic prey. |
|
| Reproduction |
| Overview: |
Males defend harems
of females on breeding beaches through aggressive
displays (inflating the proboscis and making loud
“clap-threat” vocalizations) and physical
battles. Females give birth within a few days of arrival
at the rookery. Mating occurs a few days to weeks
after cows give birth. Weaning occurs after approximately
25 days.11 |
| Time to Maturity: |
Males reach sexual
maturity at 5 years, but are usually 8-9 years old
before they can hold a territory.11 Females reach sexual
maturity after 2-
6 years (mean = 3 years).11 |
| Longevity: |
Males can live up to
14 years and females up to 19 years11 |
| Breeding
Season: |
Males arrive on breeding
beaches in early December and females arrive in late
December. Both sexes have left the beaches by early
March. |
| Frequency
of Breeding: |
Annual |
| Gestation
Period: |
~11.5 months including a delayed
implantation period of 3-4 months |
| Number of
Offspring per Pregnancy: |
One |
| Parental
Care: |
Maternal; female nurses
pup for approximately 25 days during which time the
pup will triple its weight.11 |
| Mating
System: |
Extremely polygamous;
males defend harems which may contain up to a dozen
females. |
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