Also included in the diets of many herbivores, as well as many omnivores, are fungi. Finally, several genera of tropical bats feed almost exclusively on nectar and pollen which they extract from flowers with specially evolved tongues. Ruminants chew their food more than once. It is brought up from the rumen to the mouth after a certain amount of fermentation. From there it moves on through the digestive system.
Digestion is completed in the fourth stomach and nutrients are extracted in the small intestine.
In both ruminants and non-ruminants some additional fermentation occurs in the caecum. A number of the Carnivora are omnivores though, particularly the Bears, Badgers and Mongooses. The Baleen Whales, of course, feed on crustaceans - another group of arthropods. Most of the pinnipeds feed on fish or seabirds. For the larger carnivorous mammals, the commonest prey are other mammals and birds.