Mirounga angustirostris

As is often the case in species where males compete to mate with as many females as possible, northern elephant seal males are much larger than females (1,800 kg versus 650 kg on average). Competitions can be battles, but more often involve mock threats and loud vocalizations. The dominant (alpha) male gets to mate with the most females, maximizing the number of offspring he produces. Fasting is part of their life cycle: males stay on the beach and fast for up to three months during the breeding season, while they are guarding a harem. Females stay on shore with their pups and fast for about a month while they are nursing. Afterward, males and females spend 8-10 mostly solitary months at sea. Males often migrate along a northern route and the females remain farther south. They may travel as far as Japan and log more than 20,000 km annually, spending much of their time underwater foraging for squid and fish. Dives can be as deep as 1,500 m and last as long as two hours, but the seals typically stay submerged for about 18-25 minutes and forage at depths of 350-650 m.

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The annual breeding cycle of the northern elephant seal begins in December, when the huge males haul out onto deserted beaches. Large numbers of pregnant females soon follow the males, aggregating into large groups known as harems, with each group presided over by a large, dominant male (3). Competition for this dominant position is intense (3), with males establishing their supremacy through stares, gestures, and snorts and grunts amplified by the inflation of their proboscis (2). Spectacular fights may ensue, with males delivering serious, but rarely fatal, blows with their large canine teeth (2). Between two and five days after arriving at the colony, each female will give birth to a single pup (3). For the next 27 days (2), the female will stay with her new pup, feeding it large quantities of rich, fatty milk, while she relies on her own thick blubber for sustenance (3). Shortly before the young are weaned, the females come into oestrus and mate with the dominant male. After weaning their young, the females return to sea, leaving the pups to fend for themselves (3). For the next four to six weeks, the pups practice swimming and diving, before leaving the beach where they were born to spend the next six months at sea. Northern elephant seal pups are highly vulnerable at this time, with around 30 percent perishing (3). After breeding, many northern elephant seals travel north towards Alaska to feed. Northern elephant seals feed primarily on deepwater fish and squid, a diet that necessitates an exceptional diving ability (3). They can dive down to over 1,500 metres, remaining underwater for up to an extraordinary 120 minutes, although most dives are to shallower depths and last for around 20 minutes (3). More than 80 percent of the year is spent feeding at sea, in order to build up their essential blubber stores to provide energy for breeding and moulting, times at which the seals do not feed (3). Northern elephant seals return to their southern breeding ground to moult, a process in which the very outer layer of skin is shed in addition to the hair. As rich supplies of blood are pumped to the skin to enable the growth of the new skin and hair, conserving body heat becomes essential, and so the seals do not enter the water to feed for the next three to five weeks (3). Following moulting, northern elephant seals travel northwards once more, before returning to their breeding colonies to commence the breeding cycle again. This remarkable journey, undertake twice each year, covers an impressive 10,000 kilometres (3).

On land, this enormous marine mammal may be a lumbering mass of blubber, but once in water, it transforms into a graceful swimmer and remarkable diver. One of the most striking features of the northern elephant seal is the pronounced differences between the sexes (3). Males are not only significantly larger and heavier than females, but they also have (like their namesakes) a prominent, trunk-like proboscis, and a region of thickened, scarred skin on the neck, chest and shoulders called a 'chest shield', the result of numerous fights with other males (3). The short, stiff hair of males is dark grey, fading to a rusty greyish-brown throughout the year (2). Females are generally darker than males, having a brown coat with a lighter area around the neck, which is actually scarring from being repeatedly bitten by the male during mating (2). Like other true seals (those belonging to the Phocidae family), the northern elephant seal has long, webbed feet, providing effective propulsion through the water, and forelimbs that are used to steer whilst swimming or drag themselves across land (4).

Central North Pacific, East North Pacific

Northern elephant seals are found in the eastern and north central North Pacific. Breeding takes place on offshore islands and at a few mainland localities from central Baja California to Northern California. The species breeds at over fifteen discrete locations, of which a dozen are well-known and distributed mostly in islands of southern California (USA) and Baja California (Mexico) (Condit et al. in press). A few pups are born in Oregon, Washington and southern British Columbia. Año Nuevo, in Central California, is a major breeding site.

Northern elephant seals migrate to and from their rookeries twice a year, returning once to breed from December to March and again later for several weeks to molt, at different times depending on sex and age. They also show up at additional coastal sites as far north as southern Oregon for moulting. Their post-breeding and post-moult migrations take most seals north and west to oceanic areas of the North Pacific and Gulf of Alaska twice a year. Adult males tend to travel further north and west than adult females. Wanderers have been found as far away as Japan and the Midway Islands.

Northern elephant seals are found in the coastal waters of the Pacific Ocean from the Gulf of Alaska down to Baja California. Foraging migrations by males and females are made seperately, two times yearly. Males journey north to the Aleutian Islands and the Gulf of Alaska. Females don't travel as far north, but instead migrate further west to more open ocean. The total linear distances migrated by these animals each year has been recorded at 21,000 km. Seals can be seen on shore most often from December through March, during the mating season and again beginning in April and continuing through August as they haul out for moulting.

Biogeographic Regions: nearctic (Native ); oceanic islands (Native ); pacific ocean (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Transient

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Northern elephant seals range widely in the North Pacific (regularly north to British Columbia), with males ranging farther north (as far as Gulf of Alaska and Aleutian Islands) than females. Breeding sites are distributed on islands and the mainland from the central Baja California coast north to California, including islas Guadalupe, San Benito, Cedros, Natividad (few), San Martin (few), and Coronado (few) in Mexico; and Santa Barbara, San Nicolas, San Miguel, Santa Rosa, San Clemente (few), Ano Nuevo, and Southeast Farallon islands, and Ano Nuevo Point, Point Reyes, and Piedras Balncas, in the United States; recently, pupping was observed at Shell Island, Oregon (Hodder et al. 1998). Largest breeding colony is on Guadalupe Island off Baja. Has strayed to Midway Island, Hawaii (Tomich 1986) and to a small island near Japan.

The northern elephant seal occurs in the eastern Pacific Ocean, where it breeds on approximately 15 islands and a few mainland beaches situated between northern California and the Baja California Peninsula in Mexico (2) (3). When not breeding, many northern elephant seals migrate north, along the North American coast to the Gulf of Alaska and the Aleutian Islands (3).

Northern elephant seals are generally brown in color, however there are variations to this coloration. Males are usually a darker brown, while females are a light tan color. Hair is reduced on adult males and females and is completely absent for a short time after moulting. Newborns have hair that is black in color until successfully weaned, when they shed their black coat and it is replaced by a lighter one. Countershading is a feature to all adults and newly weaned youngsters, displaying a darker color dorsally and a lighter color ventrally. They possess two, lobed hind flippers. Pinnae are absent, giving the ear the appearance of being flush with the skin. The most conspicuous feature to the male body is the inflated proboscis that adorns his face. This feature is absent in females and is larger than that of their slightly larger close relatives, southern elephant seals. Young males begin development of the proboscis at 2 years of age, but it is not fully developed until the animal reaches its 8th year of maturity. These mammals are among the largest of the group comprising aquatic carnivores in the Northern Hemisphere. Females typically weigh 600 to 900 kg and males, which outweigh females by 3 to 10 times, can top out at 2300 kg. Females reach a length of 3.1 m on average and males usually extend from 4.0 m to 5.0 m. Newborns typically weigh about 47 kg at birth. They weigh about 147 kg and measure about 1.5 m between 24 and 28 days old, when they are weaned. Teeth are dimorphic in the sexes with males having considerably enlarged canines that are used in fighting.

Range mass: 600 to 2300 kg.

Range length: 3.0 to 5.0 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes shaped differently; ornamentation

Length: 650 cm

Weight: 3500000 grams

Sexual Dimorphism: Males are much larger than females, have much larger canine teeth, and develop a large inflatable bulb on the nose.

Length:
Average: 3.8 m males; 2.5 m females
Range: 3.6-4.2 m males; 2.2-3 m females

Weight:
Average: 1,800 kg males; 650 kg females
Range: 1,500-2,300 kg males; 400-800 kg females

Habitat and Ecology

Systems

• Terrestrial
• Marine

Northern elephant seals reside terrestrially on the sandy, rocky or muddy shores of the coastline, particularly on offshore islands. They typically aggregate in large groups while on land. These animals spend only 10% of their time on land, during reproduction and moulting. The other 90% is spent in the water, diving and foraging for food, and only 11% of this time in the water is spent at the surface. This means that an extraordinary 85-90% of their time is spent at sea and under water. These mammals can dive exceptionally deep, to 500 to 600 meters (almost 1 mile) on average and to record depths of over 1500 meters for extended periods of time (20 to 70 minutes).

Range depth: 1000 (high) m.

Average depth: 500-700 m.

Habitat Regions: temperate ; terrestrial ; saltwater or marine

Terrestrial Biomes: desert or dune

Aquatic Biomes: pelagic ; coastal

Other Habitat Features: intertidal or littoral

Depth range based on 1596 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1310 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 5.161 - 22.648
  Nitrate (umol/L): 0.025 - 17.622
  Salinity (PPS): 30.381 - 34.431
  Oxygen (ml/l): 4.855 - 7.455
  Phosphate (umol/l): 0.152 - 1.777
  Silicate (umol/l): 1.436 - 38.397

Graphical representation

Temperature range (°C): 5.161 - 22.648

Nitrate (umol/L): 0.025 - 17.622

Salinity (PPS): 30.381 - 34.431

Oxygen (ml/l): 4.855 - 7.455

Phosphate (umol/l): 0.152 - 1.777

Silicate (umol/l): 1.436 - 38.397
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Marine

Comments: Northern elephant seals feed at sea (temperate and subtropical) and use beaches for breeding and molting.

In California, elephants seals occupy beaches of continental islands and the mainland during breeding (winter) and molting (spring, summer) periods; also a peak in abundance on shore occurs in October when resting females, pups of the year, and some juveniles haul out briefly. When at sea, elephant seals spend little time at the surface; commonly they are at depths of several hundred meters. Young are born on beaches of continental islands and mainland (Ano Nuevo, Point Reyes). Young stay ashore 2-3 months after weaning, leave beaches by end of April. Females generally return to natal area to breed, but some emigrate to other sites hundreds of kilometers away.

Sandy or gravel beaches, far from human activity, are the preferred breeding sites of the northern elephant seal (2). When feeding at sea, males tend to be found over continental shelves whereas females inhabit deeper open water (3).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Elephant seals make protracted migrations between breeding/molting areas and feeding grounds; over a period of 12 months, they migrate from breeding areas to feeding areas then back to breeding areas (to molt) then back to feeding areas and finally back to breeding areas (to breed); over a year, the distance traveled is about 20,000 km (Stewart and DeLong 1995). From San Miguel Island, adult females move to feeding areas at latitudes of but far away from Oregon and Washington; adult males move north to Alaska when not breeding or molting (Stewart and DeLong 1995). Many weaned pups leave breeding grounds in April, diperse north as far as Vancouver Island, return to central California coast in September. Young from southern California rookeries may move north to central California, return to island of birth to molt in spring of next year.

Northern elephant seals spend 90% of their lives in the water in order to feed. During their foraging migrations, they dive into the water repeatedly and continuously to find food, never stopping to rest or sleep for months at a time. Females and males feed separately from each other. Males travel north, remain closer to land, and tend to return to the same locations to feed year after year. Females migrate away from the land, west to the open ocean, and are less accurate in returning to the same places each year. Male foraging behavior is characterized by benthic dives to the sea floor. By contrast, females exhibit pelagic diving while foraging which is defined by a trip to the floor, a partial ascent, another trip to the floor, a partial ascent, etc. There is some speculation as to the reason why male size is so extreme in relation to female size and some suggestions indicate that food type may be a contributing factor. Males are more likely to eat food sources that are dense in mass such as sharks and skates, while females eat foods that are less dense such as squid. These differences in foods is a likely occurence to the different locales in which they are foraging. This resource partitioning is likely to be the result of differences in body size. Males are less vulnerable to predators and are thus safer foraging in areas with more predators. Females are more vulnerable to predators and thus must forage in areas with fewer predators.

While elephant seals are on land they are fasting. They go for extended periods of time without food while they are reproducing and moulting. During this time, all nutrition and energy is broken down from fat that is stored on their bodies as blubber. It is believed that these animals never drink water. Their source of water comes from food sources and broken down fats. In addition they have developed physiological methods to retain water, such as producing a concentrated urine. Another interesting phenomenon about these mammals is the behavior of eating stones before coming ashore. The true purpose of this behavior is not known. The stones are eliminated when they re-enter the water for migration, so it has been suggested that this phenomenon is in response to the long period of fasting.

Foods eaten include: cephalopods, skates, small sharks, and fish.

Animal Foods: fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

Comments: Eats cephalopods, Pacific hake and other teleosts, various cartilaginous fishes, and jawless fishes (Condit and Le Boeuf 1984). Preys mostly on mesopelagic squid; also apparently feeds commonly on bottom in deep water; commonly dives to several hundred meters. Males do not feed during breeding season.

Northern elephant seals are exceptional divers. When foraging on fishes and squid, they sometimes dive deeper than 1,500 meters and can remain submerged for 1-2 hours. After weaning her pup, a female goes to sea and spends 83-90% of her time underwater.

Northern elephant seals are important as predators on octopus, squid, small sharks, skates, and fish. In this way they impact the populations of these animals. They are also important as food for animals which prey on them, such as great white sharks and orcas.

Northern elephant seals try to feed by diving deep when in the water because the animals that view them as prey typically feed near the surface. Females migrate to the open ocean to feed in order to avoid predators as much as possible.

Known Predators:

• great white sharks (Carcharodon carcharias)
• killer whales (Orcinus orca)

Mirounga angustirostris is prey of:
Carcharodon carcharias
Orcinus orca

This list may not be complete but is based on published studies.

Mirounga angustirostris preys on:
Actinopterygii
Mollusca

This list may not be complete but is based on published studies.

10,000 to >1,000,000 individuals

Comments: Total population in the early 1990s was about 127,000.

Dominance hierarchy forms among males on breeding grounds. Highly gregarious when ashore, during breeding season and when molting. Adult females and juveniles come ashore to molt in spring, males in summer, nonpregnant females and young in fall. Preweaning mortality varies greatly among different colonies, from a few percent to sometimes 76% (see Stewart and Huber 1993 for additional survivorship data).

Comments: Adult females and juveniles return to shore to molt in April-May. Males return to beaches to molt in late spring and summer. After molting, seals go to sea again to feed before returning once again to the breeding beaches.

Because these animals spend such an extraordinary amount of time in the water, there are many gaps in how much we know about them. It is difficult to discern lifespans of these animals and what might be defined as a "natural" cause of death. Estimates of survival of reproductive females is represented in percentages with the probability of survival decreasing with each year of life. In the first year of life, a female's chances of survival are 35%, at 2 years, 30%, and at 3 years, 20%. Adult males live an average of 11 to 13 years old. Young pups are quite vulnerable to death, particularly by predation and trampling. Trampling usually happens as a result of a large male defending its females, crushing the pup under his weight as he tries to quickly move toward an intruder. By some estimates as many as 10% of the young pup population may perish this way annually.

Range lifespan
Status: wild: 18 (high) years.

Average lifespan
Status: wild: 9 years.

Typical lifespan
Status: wild: 13 (high) years.

Average lifespan
Status: wild: 6.5 years.

Average lifespan
Status: captivity: 15.0 years.

Observations: The total gestation time is about 11 months and includes a 2-3 months period of delayed implantation (Ronald Nowak 2003). Not much is known about the longevity of this species. In the wild, it is estimated that females live up to 18-20 years (Don Wilson and Sue Ruff 1999). One wild born specimen was about 15.8 years of age when it died in captivity (Richard Weigl 2005).

There is a definitive hierarchy structure to the mating system of these animals because they are polygynous and they aggregate in colonies on land during the breeding season. Each dominant male controls access to mating opportunities with a group of females. Bonner (1990) calls this mating system "female defence polygyny". Less dominant males are restricted to the fringes of a colony and continually try to gain access to females, resulting in battles between males and aggressive charges by the dominant male. Sub-dominant males usually run away but occasionally a male will challenge the dominant male in an attempt to take over the harem. Females release an audible "bawling" sound when a non-dominant male tries to mate with her. This results in a defense attempt by the dominant bull, who chases the less dominant male away. Occasionally the less dominant male becomes defiant and this can result in spectacular displays of threats and sometimes violent fighting. When a male wants to mate, he throws a flipper over the side of a female, grips her neck in his teeth and begins copulation. Resistance by a female only results in the male moving his large and heavy body on top of the female so she is unable to move. Aggressive interactions among males often result in elephant seal pups being killed by trampling. (Bonner 1990)

Mating System: polygynous

Northern elephant seals haul out for birthing and breeding from December to March. The females come into heat only 19 days after giving birth. They remain receptive for about four days, during which mating occurs. Females become sexually mature at 2 years of age, but usually begin giving birth in the 4th year of life. Males are sexually mature at the age of 6 or 7, but only occasionally are allowed to mate before they reach the age of 9 or 10 because of the hierarchy system of mating exhibited by these animals. (Reeves, et al. 1992; Bonner 1990) These animals display a phenomenon in their development cycle called delayed implantation. Delayed implantation lasts for about 3 months, resulting in a total gestation time of nearly one year. This allows both birthing and mating to occur in the same time frame, during the short period of the year when these animals are aggregated in terrestrial colonies. Interestingly, the embryo is never actually implanted, by definition of most mammals. Instead, it attaches only outwardly to the uterine wall throughout its development. (Bonner 1990; Mathews 1952)

Breeding interval: Females may breed as often as once yearly.

Breeding season: Breeding and birthing occurs from December to March.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 10 to 12 months.

Range weaning age: 23 to 27 days.

Range age at sexual or reproductive maturity (female): 2 to 10 years.

Average age at sexual or reproductive maturity (female): 9 years.

Range age at sexual or reproductive maturity (male): 2 to 10 years.

Average age at sexual or reproductive maturity (male): 9 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; delayed implantation

Average birth mass: 37500 g.

Average number of offspring: 1.

The pregnancy will ultimately last just under one year, as a result of delayed implantation. Parturition, which results in one offspring per year (although there have been occurrences of twins), will occur the following winter and lactation will follow for about 27 days before the pup is weaned. Pup weight gain during the period of lactation is phenomenal, the milk is extremely high in fat. During weaning the pup remains close to the mother until such a time that the mother leaves the pup behind to return to sea. Young pups left alone form groups or "pods", which remain on shore for up to 12 weeks without parental care. They learn to swim in the surf and eventually swim further out to sea for a short time to feed. An interesting phenomenon displayed by young male pups left to fend for themselves is that of "milk stealing". An attempt to nurse from lactating females still on the beach raising their young can give the successful pup a significant advantage in survival and higher ranking later on in his life by increasing his weight and overall health.

Parental Investment: no parental involvement; precocial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Single pup is born late December-February (rarely March), mainly in February. Pups are weaned in 4 weeks. Mating occurs a few days before the pups are weaned, then females go to sea to feed. Most adults vacate the breeding areas by the end of February. Young go to sea at 11-16 weeks, after fasting on beach for several weeks. Relatively few males (mainly 9-11 years old, or younger in newly established colonies) inseminate most of the females. Females produce their first pup usually at 3-5 years. Most females breed annually. Reproductive success increases between maternal ages of 3-7 years, then levels off; however, females breeding at a young age may experience lowered reproductive success later in life (Sydeman et al. 1991). Males live up to 15-16 years; oldest known female was 18 years old.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 2 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Lower Risk/least concern

Northern elephant seals are not presently endangered. At one time, however, this species was thought to have been hunted to extinction. They were presume extinct by the 1880's, after being exploited by hunters and whalers seeking to use the animals' thick layer of blubber as an oil source. A few animals were then discovered in 1892 which were captured and killed for scientific study. Eventually, it was discovered that a population of about 20 to 100 individuals had survived. Studies have shown that all individuals of the current population, which has grown to over 175,000, are relatives of these few survivors. The population bottleneck that occurred during this time is of concern because genetic variation is reduced, creating the possibility for the population to be vulnerable to disease or reproductive failure.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G5 - Secure

Classified as Least Concern (LC) on the IUCN Red List (1).

Population

Population Trend

Global Short Term Trend: Increase of 10 to >25%

Comments: Nearly hunted to extinction; population has increased from no more than 100 in late 1800s to 80,000 in 1984 and 127,000 in 1991 (Stewart and Huber 1993). In 1991, more than 21,000 pups were born at California rookeries, about 85% of them on San Nicolas and San Miguel islands (Reeves et al. 1992). In the mid-1990s, the California population was increasing and the Mexican population was apparently stable or decreasing (NMFS, Federal Register, 15 March 1996). See Cooper and Stewart (1983), Bodkin et al. (1985), and Stewart and Huber (1993) for discussion of increase.

Major Threats

In the past, the northern elephant seal suffered intense exploitation for its thick blubber which yields high quality oil (3). Hunting started around 1818 and by the 1860s about 250,000 seals had been killed, leaving numbers too low to make hunting worthwhile (2). On a number of occasions it was thought that the species had gone extinct, and by 1892, just a single population of about 100 individuals remained on Guadalupe Island, off northern Baja California (2). Thankfully, the implementation of legal protection allowed numbers to recover, and the northern elephant seal population slowly spread north and south until they reoccupied most of the original range (2). Today, northern elephant seals continue to increase in both number and range (3). There is some concern that commercial fisheries may be competing with the northern elephant seal for its preferred prey, but otherwise, this species faces no negative interactions with humans (3). Possibly the most serious potential threat to the northern elephant seal is the significant lack of genetic diversity in populations, the result of the drastic declines they underwent in the past. This may leave the northern elephant seal ill equipped to adapt to any changes in their environment (2).

Conservation Actions

Complete legal protection for the northern elephant seal was implemented in Mexico in 1922 (2), and subsequently, the severely depleted populations went on to display one of the most incredible recoveries ever observed in a mammal (3). The northern elephant seal is also protected in the United States under the Marine Mammal Protection Act (5).

Northern elephant seals may consume some fish and other prey that are important to the fishing industry. However, their impact is probably exaggerated.

Northern elephant seals are a huge attraction for tourists to the Año Nuevo State Reserve in California. Here visitors can watch these magnificent animals from a safe distance, during breeding season. Northern elephant seals were once hunted for their blubber, which was refined to use as oil.

Elephant seals are the only known animals capable of filling collapsed lungs. Their lungs collapse during dives. The surfactant/lubricant responsible for this ability is being researched at the Scripps Institute in San Diego for the potential benefit to premature humans with immature lungs.

Northern elephant seals have also been used in research related to the effect of weightlessness on bone density because they spend 90% of their time in a neutrally buoyant environment. NASA has used this research in their efforts to counteract the effect of weightlessnes on bone density in astronauts.

Because northern elephant seals can dive to extreme depths it has been suggested that they can greatly aid human efforts to explore and map the deep oceans once instruments that can withstand extreme pressures are developed.

Positive Impacts: ecotourism ; research and education

Comments: Nearly driven to extinction by commercial exploitation in the 1800s.