| Lobodontine seals[1] Temporal range: LateMiocene to recent | |
|---|---|
 | |
| Crabeater seal,Lobodon carcinophaga | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Phocidae |
| Subfamily: | Monachinae |
| Tribe: | Lobodontini J. E. Gray, 1869 |
| Genera | |
Thetrue sealtribeLobodontini, collectively known as theAntarctic seals orlobodontin seals, consist of four species of seals in four genera: thecrabeater seal (Lobodon carcinophaga), theleopard seal (Hydrurga leptonyx), theWeddell seal (Leptonychotes weddelli), and theRoss seal (Ommatophoca rossii). All lobodontine seals have circumpolar distributions surroundingAntarctica. They include both the world's most abundant seal (the crabeater seal) and the only predominantly mammal-eating seal (the leopard seal). While the Weddell seal prefers theshore-fast ice, the other species live primarily on and around the off-shorepack ice. Thus, though they are collectively the most abundant group of seals in the world, the combination of remote range and inaccessible habitat make them among the least well-studied of the world's seals.
The Lobondontini are thought to have diverged from theelephant seals (Mirounga) during the lateMiocene in the Southern Ocean.[2][3] The leopard and crabeater seals possess lobes and cusps on their teeth useful for straining smaller prey items out of the water (the name "Lobodontini", meaning "lobe-toothed"). Nonetheless, they have diversified into specialized preyecological niches, thereby illustrating the radiatingsympatric speciation associated with colonization of a novel environment with multiple available niches. Thus, the crabeater seal, with the most specialized sieve-like dental features, is the only seal that feeds predominantly onAntarctic krill, while the leopard seal is the only seal which actively preys on other seals andpenguins, while still retaining the ability to filter-feed on krill.[4]
The lobodontin seals in aggregate are among the most successful of all marine mammal groups, collectively accounting for at least 50% of all seals on Earth and about 80% of the globalbiomass of pinnipeds.[5] The extremely high abundance of crabeater seals in particular, with possibly over 30,000,000 individuals, is a testament to the high productivity of the Southern Ocean, especially with respect to krill.[6] High numbers of seals may also be the indirect result of the wide-scale extermination of largebaleen whales in the Antarctic due to commercial whaling in the 19th and 20th centuries, and the subsequent increase in krill densities.[7] Genetic evidence suggests that Weddell and crabeater seal populations may have increased in size during the Pleistocene.[8] None of the four species are currently thought to be declining in numbers.
.jpg)
| Image | Genus | Species |
|---|---|---|
.jpg) | LobodonGray, 1844 |
|
 | HydrurgaGistel, 1848 |
|
 | OmmatophocaGray, 1844 |
|
.jpg) | LeptonychotesGill, 1872 |
|
