The skulls of Carnivora are highly varied in form. The primary muscle powering the jaw is the temporal, and sagittal crest associated with the temporal is commonly a conspicuous part of the surface of the skull. Carnivores also have a strong zygomatic arch and a relatively large braincase. The auditory bullae and the turbinals also tend to be large and complex. The canines are large and conical.
All teeth are rooted and diphyodont .
All Carnivora have a simple stomach. Pinnipeds are found in the Otariidae and Phocidae families. All pinnipeds are large, perhaps because water conducts heat well and large animals have a low surface area to body mass ratio, which minimizes heat loss due to conduction. Their bodies are insulated by a thick layer of fat called blubber. In all species, the external ears are small or absent, the external genitalia and nipples are hidden in slits or depressions in the body, and the tail is very small.