Features of the bony orbit of the Baikal seal: comparative studies

Abstract

The research purpose is to study features of the bony orbit of the Baikal seal in comparison with another representative of aquatic mammals the fur seal. In the Baikal seal, the bony orbit is open; it lacks the zygomatic process of the frontal bone; the frontal bone and the zygomatic arch are connected by the orbital ligament, which forms a posterolateral edge of the orbit. The Baikal seal has a spherical bony orbit located on the front skull surface. The fur seal has an elliptical bony orbit located on the lateral skull surface. It also lacks the zygomatic process of the frontal bone. The orbit is of an open type. Therefore, in the Baikal seal, the field of vision is narrower than that in the fur seal. It is due to the fact that in natural conditions the Baikal seal has no natural enemies, while the fur seal is prey for larger predators.