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| Rat - A Representative Mammal |
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| Kingdom : Metazoa |
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| Subkingdom : Eumetazoa |
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| Division : Bilateria |
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| Grade : Eucoelomata |
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| Phylum : Chordata |
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| Subphylum : Vertebrata |
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| Class : Mammalia |
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| Order : Rodentia |
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| Family : Muridae |
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| Genus : Rattus |
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| Species : rattus |
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| The rat is a typical mammal. It is a nocturnal, household pest. It is normally found living in crevices and burrows. The rat has an elongated body which can be distinguished into a head, a trunk and tail. |
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| The body has an exoskeleton formed by a covering of the hairs. It is called pelage. It provides protection to the skin, as well as insulation against loss of heat. |
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| The head shows a prominent snout. At its tip is a nose which contains a nasal passage into which two external nostrils open. Below the nostrils is a cleft in the upper lip that exposes the upper two incisor teeth. This cleft is called as harelip. Eyes are not large, but the cornea protrude from the eyelids, giving a great deal of side vision. |
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| The upper and lower eyelids are movable. A nictitating membrane is present to protect the eye from dust and water. A pair of external ears (pinnae), characteristic of all mammals, are present posterio- laterally. They lead into the middle ear and the inner ear. Mouth is located subterminally. It leads into a buccal cavity. |
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| Lateral view of rat |
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| The trunk is elongated antero-posteriorly to enclose all the visceral organs. Externally it bears a pair of fore limbs and pair of hind limbs, of the same size. The limbs are typically pentadactyl with five digits each. Digits end in claws. The sole of fore limbs and hind limbs touch the ground during locomotion which is described as plantigrade. |
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| A relatively short neck connects the head to the trunk |
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| The tail is long and has a covering of small overlapping scales. It is primarily used as a balancing organ. |
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