Tuesday, January 10, 2012

Finding Food

Food is the central to an animal survival. Most each plants, for among living things the bulk generation vastly exceeds the biomass of the animals. Among these plant feeders, most of the specialists and, for example, over 100 different species of insect may depend on one tree. They vary, however, in their needs for leaves, pollen, bark, wood or roots and their different times of feeding. Larger animals are usually less selective, but there are exceptions- such as the three-toed sloth, which feeds only on the tender shoots and leave of Cecropia.

One feeding stratagem that has proved highly successful for large plant eating mammals is chewing the cud. Cud chewers take in food quickly and pass it directly to a holding comportment of the stomach. Later it returns to the mouth for complete mastication. When it is swallowed for a second time it enters another part of the stomach where digestion begins. Normally plant feeders are exposed to predators while gathering food, but a cud chewer can find itself a safe, sheltered place for the lengthy process of mastication. The success of this stratagem can be seen in a comparison of medium sized plant feeders; six species of horse like animals and two tapirs do not chew the cud, where as 40 species of deer and over 110 species of cattle, sheep and antelope are all cud chewers.