R.rattus belongs to the Phylum Chordata.
Rats have excellent memories. Once they learn a navigation route, they won't forget it. Chordates belong to the phylum Chordata, having a bilateral body plan and are deuterostome animals possessing a notochord which is a stiff rod of cartilage that extends along inside of the body that develops into the spine, in aquatic species to swim by flexing its tail.
A hollow dorsal nerve cord, in fish and other vertebrates this develops into the spinal cord, that mains the communications trunk of the nervous system. Pharyngeal slits, in fish the slits are modified to form gills, but in some other chordates they form a part of a filter–feeding system that extracts particles of food from the water in which the animals live. Post–anal tail, a muscular tail that extends backwards behind the anus. An endostyle, it is a groove in the ventral wall of the pharynx. In filter–feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus. It also stores iodine, and may be a precursor of the vertebrate thyroid gland.
Rats are extensively used for laboratory experiments
The most commonly used laboratory rat belong to the species Rattus norvegicus, kept for scientific research. Laboratory rats have served as an important animal model for research in psychology, medicine as well as in other fields. R. rattus(rat) belongs to the Phylum Chordata. Rat is cosmopolitan in distribution as it is found all over the world. Rat is nocturnal by habit as it comes out from its burrows during night for feeding purposes.
Rat is bilaterally symmetrical. Its body is about 15 to 20 cm long, somewhat cylindrical and it is covered over by soft fur of hair known as palagae. The digestive system consists of an alimentary canal and the digestive glands. A rat's circulatory system consists of a heart, blood and blood vessels. The function of blood vessels is to facilitate the circulation of blood and nutrients across the body. Lungs are the respiratory organs. The lungs lie in the thoracic cavity and are covered by visceral pleura. The nervous system consists of a central nervous system, a peripheral nervous system and an autonomic nervous system. The central nervous system consists of a brain and a spinal cord. The brain is situated in the brain box or cranium, which is connected with the first or atlas vertebra by a single occipital condyle. The excretory system is represented by a pair of kidneys, the ureters, the urinary bladder and a urino–genital canal or urethra. In rats, as in all vertebrates, sexes are separate. Male and female exhibit several differences in their external features. Rats are also used as an experimental animal to test drugs that are to be finally used by the human being.