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Rabbits are ground dwellers that live in environments ranging from desert to tropical forest and wetland. Their natural geographic range encompasses the middle latitudes of the Western Hemisphere. In the Eastern Hemisphere rabbits are found in Europe, portions of Central and Southern Africa, the Indian subcontinent, Sumatra, and Japan. The European rabbit (Oryctolagus cuniculus) has been introduced to many locations around the world, and all breeds of domestic rabbit originate from the European. Nearly half of the world's rabbit species are in danger of extinction; many are among the most vulnerable of all mammals.
The long ears of rabbits are most likely an adaptation for detecting predators. In addition to their prominent ears, which can measure up to 6 cm (more than 2 inches) long, rabbits have long, powerful hind legs and a short tail. Each foot has five digits (one reduced); rabbits move about on the tips of the digits in a fashion known as digitigrade locomotion. Full-bodied and egg-shaped, wild rabbits are rather uniform in body proportions and stance. The smallest is the pygmy rabbit (Brachylagus idahoensis), at only 20 cm in length and 0.4 kg (0.9 pound) in weight, while the largest grow to 50 cm and more than 2 kg. The fur is generally long and soft, and its color ranges through shades of brown, gray, and buff. Exceptions are the black Amami rabbit (Pentalagus furnessi) of Japan and two black-striped species from Southeast Asia. The tail is usually a small puff of fur, generally brownish but white on top in the cottontails (genus Sylvilagus) of North and South America.
Mouth Rabbits have six incisors, or front teeth, four on the top and two on the bottom. The second set of upper incisors, called peg teeth, is hidden right behind the set that can be easily seen when looking in the mouth. These teeth are used primarily for grabbing food and cutting it. The rest of the rabbit's teeth are located in the back on either side of the mouth. These molars are used for grinding the food. All of the teeth grow continuously throughout the rabbit's life and are kept worn down by the action of chewing and grinding of tooth against tooth. Cecal pellets Rabbits are hindgut digesters. This means that most of their digestion takes place in their large intestine and caecum. In rabbits, the cecum is approximately 10 times bigger than the stomach, and it, along with the large intestine, makes up roughly 40% of the rabbit's digestive tract. Cecotropes, sometimes called "night feces", come from the cecum and are high in minerals, vitamins and proteins that are necessary to the rabbit's health. Rabbits eat these in order to meet their nutritional requirements. This process allows rabbits to extract the necessary nutrients from their food. Rabbits are herbivores who feed by grazing on grass, forbs, and leafy weeds. In addition, their diet contains large amounts of cellulose, which is hard to digest. Rabbits solve this problem by passing two distinctive types of feces: hard droppings and soft black viscous pellets, the latter of which are immediately eaten. Rabbits reingest their own droppings (rather than chewing the cud as do cows and many other herbivores) in order to fully digest their food and extract sufficient nutrients. Rabbits graze heavily and rapidly for roughly the first half hour of a grazing period (usually in the late afternoon), followed by about half an hour of more selective feeding. In this time, the rabbit will also excrete many hard faecal pellets, being waste pellets that will not be reingested. If the environment is relatively non-threatening, the rabbit will remain outdoors for many hours, grazing at intervals. While out of the burrow, the rabbit will occasionally reingest its soft, partially digested pellets; this is rarely observed, since the pellets are reingested as they are produced. Reingestion is most common within the burrow between 8 o'clock in the morning and 5 o'clock in the evening, being carried out intermittently within that period. Hard pellets are made up of hay-like fragments of plant cuticle and stalk, being the final waste product after redigestion of soft pellets. These are only released outside the burrow and are not reingested. Soft pellets are usually produced several hours after grazing, after the hard pellets have all been excreted. They are made up of micro-organisms and undigested plant cell walls. The chewed plant material collects in the large cecum, a secondary chamber between the large and small intestine containing large quantities of symbiotic bacteria that aid in the digestion of cellulose and also produce certain B vitamins. The pellets are about 56% bacteria by dry weight, largely accounting for the pellets being 24.4% protein on average. These pellets remain intact for up to six hours in the stomach, the bacteria within continuing to digest the plant carbohydrates. The soft feces form here and contain up to five times the vitamins of hard feces. After being excreted, they are eaten whole by the rabbit and redigested in a special part of the stomach. This double-digestion process enables rabbits to utilize nutrients that they may have missed during the first passage through the gut and thus ensures that maximum nutrition is derived from the food they eat. This process serves the same purpose within the rabbit as rumination does in cattle and sheep. Rabbits are incapable of vomiting due to the physiology of their digestive system. |
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