Earless Seals (family Phocidae)
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- Cystophora
- Erignathus
- Halichoerus
- Histriophoca
- Hydrurga
- Leptonychotes
- Lobodon
- Mirounga
- Monachus
- Ommatophoca
- Pagophilus
- Phoca
- Pusa
The basic description of their biological traits has not changed over the centuries. The 1901 publication, Zoological series By Field Museum of Natural History, for example, describes them as follows:
Neck short; hind limbs useless for terrestrial progression; palms and soles of feet hairy; no external ear; testes abdominal, no scrotum; skull without postorbital processes and no alisphenoid canal; auditory bullae inflated.
Five developed claws on each foot, those of hind feet subequal, the first and fifth not greatly exceeding the others in length; not extending beyond toes."
All Phocidae are considered top notch swimmers, however all of them also return to land or ice for breeding.
An examination of Phocidae range reveals a geographical divide, with most of the species split on the basis of their having either a Circumpolar North (areas in and around the Arctic Ocean) or Circumpolar South (areas in and around the Southern Ocean) territory.
The grey seal (Halichoerus grypus) and the harbor seal (Phoca vitulina) generally buck the trend, having a wide, Northern Hemispheric range, primarily limited to near shore temperate water environments.
While the populations of the northern and southern Phocidae groups are considered stable, the same can not be said for the more geographically distinct species.
The IUCN, for example, lists the Caribbean Monk Seal (Monachus tropicalis) as extinct, with three additional species, the Caspian Seal (Pusa caspica), the Hawaiian Monk Seal (Monachus schauinslandi) and the Mediterranean Monk Seal (Monachus monachus) as either endangered or critically endangered.
© 2010. Patricia A. Michaels