Five Chordate Characteristics

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The five chordate characteristics are nanochord, pharynx with slits, endostyle or thyroid gland, hollow dorsal nerve cord and postanal tail. All chordates have these features sometime in their lifetimes. Theses are characteristics that appear sometime during development and either disappear or remain into adulthood. The nanochord is a primitive backbone. It lies dorsal to the coelom and under the brain and spinal cord. Its function is to allow the body to flex lateraly and keeps the body from collapsing when moving. This thin shaped rodlike feature is made of cells and fluid within rough fibrous tissue. A lamprey is a jawless fish and an example of a species with a notochord that serves as its backbone. Another chordate feature is the pharynx with slits. It is a part of the digestive tract and exists to capture food. It was used with primitive chordates as a one way filter. As the water current pushed water in the mouth and out the pharynx, the chordate collected food. Later these holes evolved into slits and gills which also helped in the respiratory system of the animal. The endostyle is homologious trait and is involved in filter feeding. In the chordated it is located on the floor of the pharynx. This glandular groove accumulates food particles and pass them also the digestive tract. It helps in iodine metabolism. This trait corresponds to the thyroid in vertebrates. A hollow dorsal nerve cord first formed in early chordate during the embryonic stage. This process is called invagination. It lies long the entire length and is dorsal to the notochord and forms into a hollow tube. In later species is is modified into the brain and spinal cord. Finally there is the postanal tail. It was generally supported by the notochord or vertebral column. In provides a method of movement in aquatic

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