Lobodontine seals Temporal range: Late Miocene to recent |
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Crabeater seal, Lobodon carcinophaga | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Suborder: | Caniformia |
Superfamily: | Pinnipedia |
Family: | Phocidae |
Subfamily: | Monachinae |
Tribe: | Lobodontini |
Genera | |
The true seal tribe Lobodontini, collectively known as the lobodontine seals, consist of four species of seals in four genera: the crabeater seal (Lobodon carcinophaga), the leopard seal (Hydrurga leptonyx), the Weddell seal (Leptonychotes weddelli), and the Ross seal (Ommatophoca rossii). All lobodontine seals have circumpolar distributions surrounding Antarctica. 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 the shore-fast ice, the other species live primarily on and around the off-shore pack 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 the elephant seals (Mirounga) in the late Miocene or early Pliocene after moving southward from the Atlantic to the Southern Ocean. All species share teeth adaptations including lobes and cusps useful for straining smaller prey items out of the water (the name "Lobodontini", meaning "lobe-toothed"). Nonetheless, they have diversified into specialized prey ecological niches, thereby illustrating the radiating sympatric 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 on Antarctic krill, while the leopard seal is the only seal which actively preys on other seals and penguins, while still retaining the ability to filter-feed on krill.