Lobodon carcinophaga
Creators: name: Russell A. Mittermeier
name: Don E. Wilson
Publisher: name: Lynx Edicions
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Carnivora
Phocidae
Lobodon
Lobodon carcinophaga

description: 7.
Crabeater Seal
Lobodon carcinophaga
French: Phogue crabier / German: Krabbenfresser / Spanish: Foca cangrejera
Taxonomy. Phoca carcinophaga Hombron & Jacquinot, 1842,
no type locality given.
Identified by J. B. Hombron and H. Jacquinot in 1853 as “sur les glaces du Pole Sud, entre les iles Sandwich et les iles Powels, a 150 lieues de distance de chacune de ces iles.” (= about the ice of the south pole, between [south] Sandwich and Powel [= south Orkney] Islands, 150 leagues [= 724 km] distance from each of these islands).
The specific epithet is often changed from the original feminine form, carcinophaga, and given incorrectly in the masculine form, carcinophagus, because it was recombined with the masculine name Lobodon. Here, carcinophaga (meaning crab eater) is a compound “noun in apposition,” and according the International Committee on Zoological Nomenclature, it should not be changed from the original spelling when recombined with a masculine generic name. Monotypic.
Distribution. Circumpolar in the Southern Ocean.
Descriptive notes. Total length averaged 230-9 cm (SD + 11-4 cm, males) and 235-6 cm (SD + 11-8 cm, females); weight averaged 198-7 kg (SD + 16-9 kg, males) and 206-5 kg (SD + 22-6 kg, females). Newborns are c.114 cm in length and weigh c.36 kg. Adult female Crabeater Seals tend to be longer and heavier than males. Crabeater Seals have long slender bodies with relatively long front flippers and slender, long, and upturned snouts. Offspring have a short thick tan to grayish lanugo (fine, soft hair) that they molt when they are weaned at c.3—4 weeks old. During most of the year, adults have a uniform brown to yellowish dorsal pelage and a lighter ventral pelage, with dark blotches on sides particularly around front and rear flippers. After they molt old hair, they have a mostly dark-gray to silver background, darker dorsally and lighter ventrally, with some light spots scattered on dorsal pelage. Post-canine teeth are specifically adapted and multicusped for straining seawater and catching small krill, much like baleen in large whales. Most Crabeater Seals have long, paired scars on their bodies that are inflicted mostly during their first 1-2 years oflife by Leopard Seals (Hydrurga leptonyx) that hunt them. Other small scars around front flippers, sides of head, and neck are caused from biting each other during mating or during interactions between breeding males.
Habitat. Mostly pack-ice habitats around the Antarctic continent. Highest densities of Crabeater Seals occur along edges of pack ice and just over edges of the Antarctic continental shelf.
Food and Feeding. About 95% of the diet of the Crabeater Seal consists of Antarctic krill (Euphausia superba), although they eat small amounts of fish and squid during some seasons. They catch krill when they are swarming by sucking seawater into their mouths and then expelling it through their sieve-like post-canine teeth that retain the krill. They can catch sparsely distributed krill under the ice by sucking in individuals from several centimeters or more away. Most foraging by Crabeater Seals in summer is at night to depths of ¢.100 m, although the deepest recorded dive was more than 600 m and lasted about five minutes.
Breeding. In late September—October, Crabeater Seals occur widely scattered on ice floes as triads of an adult female, her offspring, and an adult male that appears to remain with the female until she comes into estrus c.3—4 weeks after giving birth. A female Crabeater Seal mates within 1-4 days after she weans her offspring. After that, adult males often search for other estrous females and might briefly compete with other males for access to them. Crabeater Seals can live up to 40 years, but 20-25 years is more typical.
Activity patterns. Crabeater Seals molt in January-February and spend a bit more time hauled out on ice than at other times of the year. When not hauled out on ice to breed or molt, Crabeater Seals appear to dive continually during the night and then haul-out briefly to rest during the day. They haul-out on ice during the daytime, and ice floes are often stained red by their krill-dominated feces. Only ¢.20% of Crabeater Seals in an area are generally on the ice at one time, even when they spend more time hauled out while molting.
Movements, Home range and Social organization. Crabeater Seals move over great distances during the year, either being carried by drifting ice or by actively traveling to search for concentrations of Antarctic krill. They are mostly solitary when foraging and traveling, although groups of a couple dozen or more occasionally haul-out on the same ice floes, but they are not particularly social even then.
Status and Conservation. Classified as Least Concern on The IUCN Red List. Crabeater Seals are thought to be perhaps the most abundant of phocid carnivores, mostly from extrapolations from surveys in small accessible pack-ice areas. Estimates have ranged from several millions to 75 million individuals. More recent circum-Antarctic surveys and genetic analyses suggest much smaller numbers, although they still seem to be relatively abundant. Crabeater Seals were killed in some areas to feed sled dogs during the early and mid-1900s, and Soviet sealers harvested small numbers in 1986-1987. A large mass mortality of Crabeater Seals occurred in 1955, evidently caused by virulent distemper-like virus.
Bibliography. Adam (2005), Bengtson & Cameron (2004), Bengtson & Siniff (1981), Bengtson & Stewart (1992), Bengtson et al. (2011), Burns et al. (2004), Curtis et al. (2007), Hombron & Jacquinot (1853), Laws & Taylor (1957), Laws et al. (2003a, 2003b), Nordey et al. (1995), Rice (1998), Siniff & Bengtson (1977), Wall et al. (2007).
description: Published as part of Russell A. Mittermeier & Don E. Wilson, 2014, Phocidae, pp. 120-183 in Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona :Lynx Edicions on page 174, DOI: 10.5281/zenodo.6607185