Comparative Anatomy

Most people are have encountered the phrase “You are what you eat!”? This statement may be more accurate then one might initially think. Mammals are most often grouped as carnivore, herbivore and sometimes omnivore. These classifications are based on the diet and manner in which an individual obtains food. Carnivores generally eat other carnivores, while herbivores commonly eat herbs, also termed as plants or vegetation. Hence, in a way, you are what you eat. Although carnivores generally eat other carnivores there are many which feed on herbivores. Moreover, other individuals eat both herbs and other carnivores and/or herbivores, these individuals are known as omnivores, Omni- meaning all. Mammals are anatomically, physiologically and behaviorally adapted to procure and consume a particular type of diet (Mills 1). By comparing the oral cavity, digestive tract of carnivores and herbivores we can determine some of the specialized characteristics within each classification.

The oral cavity consists of the cavern between the mouth and pharynx containing the tongue and teeth (Kent 491). Carnivores typically have a wide mouth opening in relation to head size. The large mouth affords advantages in the seizing of prey. Carnivore teeth are specifically spaced as not to trap string debris (Mills 2). The incisors are short, pointed and prong like, very efficient at grasping and shredding. The canines are notably elongated and dagger-like, used for stabbing, tearing and killing prey. The molars are flattened and triangular with jagged edges, when the jaw of a carnivore closes, the molars slide past each other causing a slicing motion very sufficient at shearing meat from bone. The saliva produced within the oral cavity of carnivores contains no enzymes. When feeding, a carnivore gorges itself quickly and does not chew its food (Mills 4), it simply bites off huge chunks of meat and swallows them whole. Since protein digesting enzymes would be damaging to the oral cavity there is no need for carnivores to mechanically chew food and produce digestive enzymes in the oral cavity. The oral cavity of the common herbivore on the other hand is quite different. Herbivores customarily have a relatively small opening into the mouth relative to the head and a thick muscular tongue to aid in chewing. The types and number of teeth vary depending on the form of vegetation a particular species is adapted to eating. Although diverse, herbivore dentition shares common structural features. Herbivore teeth are tightly arranged which permits biting and cropping. The arrangement of teeth also functions to wall in the oral cavity to provide adequate space for consumption. The incisors are broad, flattened and spade-like (Mills 7). The assorted canines may be small as with equestrians (horses), prominently displayed in hippos, pigs and some primates or absent altogether. The molars are usually square and flat topped to allow for adequate grinding. The molars do not slide past each other to provide slicing motions, instead slide horizontally to crush and pulverize. Herbivores prudently and purposefully chew their food, continuously grinding the food with their teeth, tongue and cheek muscles. The meticulous and slow process is essential to agitate plant cell walls and guarantee mixing of digestible material with saliva. The importance of thorough mixing is significant because the saliva of herbivores regularly contain carbohydrate-digesting enzymes, which begin the process of breaking down food molecules in the mouth. Comparing the oral cavity of carnivores and herbivores it is evident the specialization teeth, tongue and salivary glands have undergone to compensate for the different diets consumed.

The digestive tract readily includes major tissues such as the mouth, stomach, intestines, colon and any accessory organs (pancreas, live, gallbladder, etc). The most striking difference between carnivores and herbivores are seen in these organs. A carnivore typically gorges itself only once a week, hence a large stomach volume is advantageous, allotting the carnivore to gorge itself quickly and then digest later while resting (Anatomical Adaptation….3). The carnivore stomach is about 60-70 % of the total capacity of the digestive system. Because protein is readily digested and absorbed the small intestine is traditionally short (Molles 146). Carnivores are able to sustain a continuously low stomach pH, around 1-2, regardless of the volume of food in the stomach. The extremely low pH is necessary to expedite protein breakdown and destroy the menacing bacteria readily associated with