As previously covered, herbivores and carnivores display adaptations relating to their feeding practices. These extend to the teeth, enzymes produced, length of intestine and beyond.
Herbivores adapted to a high cellulose diet such as ruminants have specialised teeth. They do not have incisors which are used to tear flesh in carnivores. Instead, they have a dental pad that helps chew plants. Looks so weird, took me a while to understand what was going on.
To help with the constant grinding, their teeth also grow continuously.
Gut-wise, they have four compartments: the rumen, reticulum, omasum and abomasum.
In the first two sections, the rumen and the reticulum, food is digested with saliva and a process of separation of liquids from solids takes place. The solids become the bolus.
OK, put your drink down for this bit: the food is then regurgitated to mix it with more saliva and break it into smaller pieces again. Food gets fermented by microorganisms in these two compartments.
Upon passing into the omasum, the first absorption take place in the form of water and inorganic ions being taken up into the bloodstream. Then the food arrives in the equivalent of the “stomach”, the abomasum which operates in familiar ways: enzymes, rumbling and low pH break down food.
Absorption of nutrients takes place in the small intestine, while the final stage of digestion in the large intestine involves further fermentation, the same way as in the reticulorumen (rumen+reticulum).
Carnivores are known for their massive canines which are used to tear the flesh of their prey. Notice their molars aren’t as broad and ridged compared to herbivores, since they don’t need to do much grinding of their food.
The jaw and its clenching movement is also powerful and works alongside the teeth to enable catching prey. Eyes of carnivores, as observed by comparing carnivore and herbivore skulls, are positioned forward to enable chasing prey. Some carnivores such as crocodiles have sideways facing eyes because they ambush prey rather than chase it.
In order to deal with digestion of high-protein food, carnivores show some gut adaptations. Flesh is relatively easier to digest, as it doesn’t have much of the cellulose that plant food has. One of these is adaptations is the shorter gut.
Not requiring the digestion of high carbohydrate content food, no amylase production takes place in the mouth via saliva to break down carbohydrates. The stomach is more acidic and stays acidic during digestion, to cope with breaking down raw flesh food. The stomach does not need multiple compartments for prolonged digestion. In its highly acidic environment, the digestive enzymes secreted are very functional, something most enzymes wouldn’t be able to accomplish at a pH as low as 1. Herbivores and omnivores only maintain a pH of around 4 (pH varies between 1-14 where 7 is neutral).