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Lifespan, longevity, and ageing

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Observations: The total gestation time of about 10 months includes a period of delayed implantation (Ronald Nowak 2003). In the wild, these animals have been estimated to live up to 39 years (Ronald Nowak 1999). Their longevity in captivity has not been studied in detail and hence their maximum longevity remains unknown.
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Untitled

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The large population of crabeater seals has been associated with the near-extinction of the large baleen whales. This is because the whales, like the crabeater seal, eat krill. Now there is probably more krill available to the crabeater seal. It is hypothesized that changes in sexual maturity and other reproductive characteristics correlate with large ecological changes such as this. Bengston and Siniff (1981) have shown that the age of sexual maturity of the crabeater has significantly decreased since the 1950s.

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associations

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When the crabeater seal is approached it snorts, hisses, and bares its teeth. If caught, it rolls over several times. This is probably an avoidance tactic developed for its primary predators, the killer whale (Orcinus orca) and the leopard seal (Hydrurga leptonyx) (Stirling and Kooyman 1971).

Known Predators:

  • killer whales (Orcinus orca)
  • leopard seals (Hydrurga leptonyx)
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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Morphology

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After the summer moult, the crabeater seal is dark brown dorsally and grades to blonde ventrally. It has darker brown markings on the back and sides over the paler brown pelage. The flippers are the darkest parts of the body. Its fur slowly changes to blonde throughout the year and it is almost entirely blonde by the summer. In fact it has been called "the white Antarctic seal" (Kooyman 1981). It has a long snout and a fairly slim body compared to other seals. Females are slightly larger on average than males with a length from 216 cm to 241 cm. Males range from 203 cm to 241 cm.

The crabeater seal often has long scars running along the sides of its body. These are most likely inflicted by its major predator, the leopard seal, Hydrurga leptonyx (Siniff and Bengston 1977).

Its teeth are very distinct and have been called "the most complex of any carnivore" (Kooyman 1981). There are several tubercles on each tooth with spaces between them that cut deeply into the tooth. The main cusps of upper and lower teeth fit perfectly together. When the crabeater seal closes its mouth, the only spaces are those between the tubercles. This arrangement probably serves as a sieve through which to strain krill, their primary food source. (Kooyman 1981, Nowak 1997).

Range mass: 200 to 300 kg.

Range length: 203 to 241 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Habitat

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The crabeater seal lives on the pack ice and the near freezing water surrounding Antarctica.

Habitat Regions: polar ; saltwater or marine

Terrestrial Biomes: icecap

Aquatic Biomes: pelagic ; coastal

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Distribution

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The crabeater seal, Lobodon carcinophaga, is primarily found on the coast and pack ice of Antarctica. In the winter months, it may be found on the shores of South America, Australia, South Africa, Tasmania, New Zealand, and various islands surrounding Antarctica. In the winter its range covers about 22 million sq km. (Kooyman 1981, Nowak 1997).

Biogeographic Regions: ethiopian (Native ); neotropical (Native ); australian (Native ); antarctica (Native ); oceanic islands (Native ); atlantic ocean (Native ); pacific ocean (Native )

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Trophic Strategy

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The crabeater seal appears to be a misnomer as there is no evidence that it eats crabs. Its primary food is krill, Euphausia superba. It probably also eats other invertebrates. The crabeater seal feeds by swimming through a school of krill with its mouth open, sucking them in and then sieving the water out through its specialized dentition (Kooyman 1981, Nowak 1997). Klages and Cockcroft (1990) report that a captive crabeater seal was able to suck small fish into its mouth at distances of up to 50 cm. They note that this prey is much larger than the krill that it would consume in the wild, and suggest that it could probably suck krill in from a much greater distance. The seal preferred fish smaller than 12 cm and swallowed everything whole, in contrast to many seals which tear their food up with their teeth before swallowing. It was often observed exploring the bottom of its pool and sucking up debris. Klages and Cockcroft suggest that this is an adaption to winter feeding on krill in the Antarctic. At this time of year, krill is mainly found in crevices and caverns. The seal may be able to suck the krill out from these unreachable areas. Feeding probably occurs prinicipally at night (Nowak 1997).

Animal Foods: aquatic crustaceans; other marine invertebrates

Primary Diet: carnivore (Eats non-insect arthropods)

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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Since crabeater seals occupy a habitat that is fairly inaccessible to humans, there has been very little contact between the two species. There is a report, however, that a young crabeater seal found on the coast of South Africa was easily tamed and trained (Klages and Cockcroft 1990).

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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Commercial fisheries have expressed interest in exploiting Antarctica's krill resources. As this is the primary food of the crabeater seal, there are bound to be negative consequences associated with the crabeater seal in this budding industry (Nowak 1997).

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Conservation Status

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The crabeater seal is the most numerous species of pinniped in the world, with a population estimated at between 15 and 40 million. Since its habitat is remote, the only concerns for conservation are indirect. Trace amounts of chemicals such as DDT have been found in populations of the crabeater seal, and if the fishing industry decides to use the krill in the Antarctic seas, the major food source of these seals may be severly depleted (Kooyman 1981). Now, however, its numbers appear to be stable.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Behavior

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Perception Channels: tactile ; chemical

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Reproduction

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Reproduction in the crabeater seal probably takes place on the pack ice surrounding Antarctica in the austral spring, from October to December (Kooyman 1981). Starting in September, a pregnant female occupies a space on the ice floe in which she gives birth and cares for her single pup. A male joins the female in her chosen area just before or just after parturition. He defends the female and the newborn pup. He is, in all likelihood, not the father of the pups. Females come into estrus just after weaning and Siniff et al. (1979) report that the male's only apparent interest is in waiting for the female to be sexually receptive. Males aggressively defend females from other intruding males. It is not clear if the males join the females because of a female cue such as scent or because of the pup.

Mating System: monogamous

Pups are born weighing approximately 20 kg and gain weight while nursing at about 4.2 kg/day (Shaughnessy and Kerry 1989). Physical contact between the mother and pup during this period is necessary. If either the pup or the mother strays, the other immediately follows. Pups are weaned at about 3 weeks old. It is unclear if physical mechanisms in the mother, such as reduced milk production, cause the weaning or if the defending male drives the pup and mother apart. Throughout the lactation period the male is aggressive towards the female. She defends herself by biting him on the neck and sides. By the end of lactation her body weight may be reduced by half, so she would be unable to defend herself adequately. She becomes sexually receptive shortly after weaning and, unlike most seals, copulation appears to occur on the ice floes instead of in the water (Shaughnessy and Kerry 1981; Siniff et al. 1979)

Gestation lasts about 11 months and probably includes a period of delayed implantation (Nowak 1997). Crabeater seals become sexually mature between 3 and 4 years of age and females may have successful pregnancies between 5 and 25 years old (Bengston and Siniff 1981).

Breeding season: Reproduction in the crabeater seal probably takes place on the pack ice surrounding Antarctica in the austral spring, from October to December.

Average number of offspring: 1.

Average gestation period: 11 months.

Average weaning age: 3 weeks.

Average time to independence: 3 weeks.

Range age at sexual or reproductive maturity (female): 3 to 4 years.

Range age at sexual or reproductive maturity (male): 3 to 4 years.

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

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

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Batty, K. 2008. "Lobodon carcinophaga" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lobodon_carcinophaga.html
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Kristin Batty, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Diagnostic Description

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In Crabeater seals, the head and muzzle are moderately long and thin relative to the animal's overall size. The eyes are set fairly far apart and the head tapers to the base of the straight muzzle, forming a slight forehead in profile. The nostrils are on top of the muzzle, just back from the end. The line of the mouth is virtually straight. The vibrissae are short, pale to clear, and inconspicuous. The foreflippers are long, oar shaped, and pointed, like those of otariids. The first digits are elongated and robust, and the fifth digit is reduced. Many crabeaters bear long dark scars, either singly or as a parallel pair, attributable to attacks by leopard seals. The coat of a freshly moulted crabeater has a rich sheen, with light to dark tones of silvery grey to yellowish brown. There are irregular patches of spots and rings, often in clusters on the sides, flippers, and around the insertions of the flippers. These markings produce a reticulated, or weblike, pattern on many crabeaters. The flippers can be so heavily marked with spots and rings that they appear darker than the rest of the body. As the year progresses, crabeaters fade dramatically, virtually eliminating the contrast between top and bottom. As these seals become older they become paler overall, and some look faded all year. Pups are born with a soft woolly coat that is greyish brown, with darker colouring on the flippers. Moult begins in about 2 to 3 weeks and the pup sheds into a subadult pelage similar to that of the adult. Most crabeaters have at least a few and often many long scars on the body, which are most often seen in pairs, parallel or near to each other. These scars are thought to be the result of unsuccessful leopard seal attacks on the seals as juveniles. Additionally many older animals are extensively scarred on the neck, face, and around the lower jaws. All of the post-canine teeth are ornate, with multiple accessory cusps. Upper and lower teeth interlock to form a network for straining krill from the water. The dental formula is I 2/2, C 1/1, PC 5/5. Can be confused with: Crabeater seals are most likely to be confused with leopard seal and Weddell seal. The former has a massive reptilean head, long foreflippers, and huge maw. The latter has a very small head, relative to the rotund body, and a distinctly spotted coat. Only crabeaters occur routinely in large groups.
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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Size

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Adults reach 2.6 m in length and, although little data is available, weigh an estimated 200 to 300 kg. Neonates are thought to be at least 1.1 m and 20 to 40 kg.
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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Brief Summary

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Pups are born from September to December, and mating most likely occurs from October through December (although little is known about their reproduction). There are no specific rookeries: females haul out on ice, give birth, and aggressively ward off other seals, particularly males. Crabeaters are frequently encountered alone or in small groups of up to 10 on the ice or in the water. However, much larger groups of up to several thousands have been observed. Occasionally, they can be seen traveling together in herds, breathing and diving almost synchronously. They are known for their ability to move rapidly on ice, with sinuous serpentine motions of the back, aided by the flippers, When agitated, their response is to arch their back and raise their neck and head, and often point the nose upwards at a slight angle in an alert posture.Recent research has revealed that crabeater seals can dive to 430 m and for 11 minutes, although most feeding dives were much shallower and shorter. It is believed that crabeaters feed with greatest intensity at night, mostly on krill.
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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Food and Agriculture Organization of the UN
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Benefits

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Conservation Status : Crabeater seals have never been seriously exploited by humans. They continue to be taken for scientific research and to feed sled dogs kept at Antarctic bases. They are probably the most numerous pinniped, and may be the most numerous large mammal on earth besides humans. It has been speculated that the population of crabeater seals is at an all time high due to the demise of the large stocks of krill-eating baleen whales. IUCN: Insufficiently known.
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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Food and Agriculture Organization of the UN
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Crabeater seal

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The crabeater seal (Lobodon carcinophaga), also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized (over 2 m in length), relatively slender and pale-colored, found primarily on the free-floating pack ice that extends seasonally out from the Antarctic coast, which they use as a platform for resting, mating, social aggregation and accessing their prey. They are by far the most abundant seal species in the world. While population estimates are uncertain, there are at least 7 million and possibly as many as 75 million individuals.[2] This success of this species is due to its specialized predation on the abundant Antarctic krill of the Southern Ocean, for which it has uniquely adapted, sieve-like tooth structure. Indeed, its scientific name, translated as "lobe-toothed (lobodon) crab eater (carcinophaga)", refers specifically to the finely lobed teeth adapted to filtering their small crustacean prey.[3] Despite its name, crabeater seals do not eat crabs. As well as being an important krill predator, the crabeater seal's pups are an important component of the diet of leopard seals (H. leptonyx). They are the only member of the genus Lobodon.

Taxonomy and evolution

The genus name of the crabeater seal, Lobodon, derives from Ancient Greek meaning "lobe-toothed", and the species name carcinophaga means "crab eater."[3] The crabeater seal shares a common recent ancestor with the other Antarctic seals, which are together known as the lobodontine seals. These include the leopard seal (Hydrurga leptonyx), the Ross seal (Ommatophoca rossii), and the Weddell seal (Leptonychotes weddelli).[4] These species, collectively belonging to the Lobodontini tribe of seals, share teeth adaptations including lobes and cusps useful for straining smaller prey items out of the water column. The ancestral Lobodontini likely diverged from their sister clade, the Mirounga (elephant seals) in the late Miocene to early Pliocene, when they migrated southward and diversified rapidly in the relative isolation around Antarctica.[4]

Description

Illustration of the skull

Adult seals (over five years old) grow to an average length of 2.3 m (7.5 ft) and an average weight of around 200 kg (440 lb). Females are on average 6 cm (2.4 in) longer and around 8 kilograms (18 lb) heavier than males, though their weights fluctuate substantially according to season; females can lose up to 50% of their body weight during lactation, and males lose a significant proportion of weight as they attend to their mating partners and fight off rivals.[5] During summer, males typically weigh 200 kilograms (440 lb), and females 215 kilograms (474 lb). A molecular genetic based technique has been established to confirm the sex of individuals in the laboratory.[6] Large crabeater seals can weigh up to 300 kg (660 lb).[7] Pups are about 1.2 metres (3.9 ft) in length and 20 to 30 kilograms (44 to 66 lb) at birth. While nursing, pups grow at a rate of about 4.2 kilograms (9.3 lb) a day, and grow to be around 100 kilograms (220 lb) when they are weaned at two or three weeks.[3][8]

These seals are covered mostly by brown or silver fur, with darker coloration around flippers. The color fades throughout the year, and recently molted seals appear darker than the silvery-white crabeater seals that are about to molt. Their body is comparatively more slender than other seals, and the snout is pointed. Crabeater seals can raise their heads and arch their backs while on ice, and they are able to move quickly if not subject to overheating. Crabeater seals exhibit scarring either from leopard seal attacks around the flippers or, for males, during the breeding season while fighting for mates around the throat and jaw.[3] Pups are born with a light brown, downy pelage (lanugo), until the first molt at weaning. Younger animals are marked by net-like, chocolate brown markings and flecks on the shoulders, sides and flanks, shading into the predominantly dark hind and fore flippers and head, often due to scarring from leopard seals. After molting, their fur is a darker brown fading to blonde on their bellies. The fur lightens throughout the year, becoming completely blonde in summer.

Crabeaters have relatively slender bodies and long skulls and snouts compared to other phocids. Perhaps their most distinctive adaptation is the unique dentition that enables this species to sieve Antarctic krill. The postcanine teeth are finely divided with multiple cusps. Together with the tight fit of the upper and lower jaw, a bony protuberance near the back of the mouth completes a near-perfect sieve within which krill are trapped.[3]

Distribution and population

Crabeater seals have a continuous circumpolar distribution surrounding Antarctica, with only occasional sightings or strandings in the extreme southern coasts of Argentina, South Africa, Australia and New Zealand.[3] They spend the entire year on the pack ice zone as it advances and retreats seasonally, primarily staying within the continental shelf area in waters less than 600 m deep.[9] They colonized Antarctica during the late Miocene or early Pliocene (15-25 million years ago), at a time when the region was much warmer than today. The population is connected and fairly well mixed (panmictic), and genetic evidence does not suggest any subspecies separations.[10] A genetic survey did not detect evidence of a recent, sustained genetic bottleneck in this species,[11] which suggests that populations do not appear to have suffered a substantial and sustained decline in the recent past.

Currently, no reliable estimates of the total crabeater seal population are available. Past estimates relied on minimal opportunistic sighting and much speculation, ranging from 2 million[12] to 50-75 million individuals.[13] Genetic evidence suggests that crabeater population numbers may have increased during the Pleistocene.[14] The most recent point estimate is 7 million individuals,[15] but this, too, is considered a likely underestimate.[1] An international effort, the Antarctic Pack Ice Seal initiative, is currently underway to evaluate systematically collected survey data and obtain reliable estimates of all Antarctic seal abundances.[3]

Behavior

Two crabeater seals

Crabeater seals have a typical, serpentine gait when on ice or land, combining retractions of the foreflippers with undulations of the lumbar region.[2] This method of locomotion leaves a distinctive sinuous body track and can be extremely effective. When not subject to overheating (i.e. on cold days), speeds on land of 19–26 km/h (12–16 mph) have been recorded for short distances.[2] Satellite tracking data have resulted in conservative estimates of swimming speeds of 66 km/day and 12.7 km/h. While swimming, crabeaters have been known to engage in porpoising (leaping entirely out of the water) and spyhopping (raising the body vertically out of the water for visual inspection) behaviors.[2]

The most gregarious of the Antarctic seals, crabeaters have been observed on the ice in aggregations of up to 1,000 hauled out animals and in swimming groups of several hundred individuals, breathing and diving almost synchronously. These aggregations consist primarily of younger animals. Adults are more typically encountered alone or in small groups of up to three on the ice or in the water.[3]

Crabeater seals give birth during the Antarctic spring from September to December.[16] Rather than aggregate in reproductive rookeries, females haul out on ice to give birth singly. Adult males attend female-pup pairs until the female begins estrus one to two weeks after the pup is weaned before mating. Copulation has not been observed directly and presumably occurs in water. Pups are weaned in about three weeks,[17] at which time they are also beginning to molt into a subadult coat similar to the adult pelage.[2]

Curiously, crabeater seals have been known to wander further inland than any other pinniped. Carcasses have been found over 100 km from the water and over 1000 m above sea level, where they can be mummified in the dry, cold air and conserved for centuries.[18]

Mummified crabeater seal in the Asgard mountains

Ecology

Diet

Illustration of the teeth of crabeater seals which are used to strain krill from the water

Despite its name, the crabeater seal does not feed on crabs (the few crab species in its range are mostly found in very deep water[19]). Rather, it is a specialist predator on Antarctic krill (Euphausia superba), which comprise over 90% of the diet.[2] Their high abundance is a testament to the extreme success of Antarctic krill, the single species with the greatest biomass on the planet.[20] There is little seasonality in their prey preference, but they may target adult and male krill.[2] Other prey items include cephalopods and diverse Antarctic fish species.[2] Although the crabeater seal is sympatric with the other Antarctic seal species (Weddell, Ross and leopard seals), the specialization on krill minimizes interspecific food competition. Among krill-feeding whales, only blue whales (Balaenoptera musculus) and minke whales (B. acutorostrata) extend their range as far south as the pack ice where the crabeater seals are most frequent.[2]

Photo of crabeater teeth

While no reliable historical population estimates have been done, population models suggest crabeater seal populations may have increased at rates up to 9% a year in the 20th century, due to the removal of large baleen whales (especially the blue whale) during the period of industrial whaling and the subsequent explosion in krill biomass and removal of important competitive forces.[21]

Predation

Crabeater seal with visible scars on the neck

Young crabeater seals experience significant predation by leopard seals. Indeed, first-year mortality is exceedingly high, possibly reaching 80%, and up to 78% of crabeaters that survive through their first year have injuries and scars from leopard seal attacks.[1] Long scars and sets of parallel scars, visible on the otherwise pale and relatively unmarked pelage of crabeaters, are present on nearly all young seals. The incidence of visible scars falls off significantly after the first year, suggesting leopard seals primarily target the young of the year.[22] The high predation pressure has clear impacts on the demography and life history of crabeater seals, and has likely had an important role in shaping social behaviors, including aggregation of subadults.[2]

Predation by killer whales (Orcinus orca) is poorly documented, though all ages are hunted.[23] While most predation occurs in the water, coordinated attacks by groups of killer whales creating a wave to wash the hauled-out seal off floating ice have been observed.[24] Orca packs generally pursue other seals, however, as crabeaters are known to be a tenacious species that make themselves more trouble to catch than they're worth.

Gallery

See also

References

  1. ^ a b c Hückstädt, L. (2015). "Lobodon carcinophaga". IUCN Red List of Threatened Species. 2015: e.T12246A45226918. doi:10.2305/IUCN.UK.2015-4.RLTS.T12246A45226918.en. Retrieved 19 November 2021.
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Crabeater seal: Brief Summary

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The crabeater seal (Lobodon carcinophaga), also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized (over 2 m in length), relatively slender and pale-colored, found primarily on the free-floating pack ice that extends seasonally out from the Antarctic coast, which they use as a platform for resting, mating, social aggregation and accessing their prey. They are by far the most abundant seal species in the world. While population estimates are uncertain, there are at least 7 million and possibly as many as 75 million individuals. This success of this species is due to its specialized predation on the abundant Antarctic krill of the Southern Ocean, for which it has uniquely adapted, sieve-like tooth structure. Indeed, its scientific name, translated as "lobe-toothed (lobodon) crab eater (carcinophaga)", refers specifically to the finely lobed teeth adapted to filtering their small crustacean prey. Despite its name, crabeater seals do not eat crabs. As well as being an important krill predator, the crabeater seal's pups are an important component of the diet of leopard seals (H. leptonyx). They are the only member of the genus Lobodon.

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