Chordata

Chordata
The word ‘Chordata’ is made up of two greek words ‘Chorde’ which means rod or rope or string like structure and ‘ata’ means bearer group. Chordates are those animals which have notochord in their body.
Chordates show four features, at different stages in their life. They are:
1. Notochord– It is a longitudinal rod that is made of cartilage and runs between the nerve cord and the digestive tract. Its main function is to support the nerve cord. In Vertebrate animals, the vertebral column replaces the notochord.
2. Dorsal Nerve Cord – This is a bundle of nerve fibres which connects the brain to the muscles and other organs.
3. Dorsal tubular nervous system- A nerve chord is found in the dorsal side of the body extending anterior to posterior end. At anterior end it become condensed and form brain, which a part of central nervous system.
4. Post-anal tail – This is an extension of the body beyond the anus. In some chordates, the tail has skeletal muscles, which help in locomotion.
5. Pharyngeal gills–They are the openings which connect the mouth and the throat. These openings used for respiration.
6. Postanal Tail - It is an extension of the body to the anus. In chordates, the tail is composed of skeletal muscles which help in locomotion in fish-like species. It is absent in most of the adult Chordates.
7. Bilaterally symmetrical, triploblastic, coelomic and segmented body.
8. The body design is complex and well-differentiated.
9. The body has an organ system level of organization
10. Heart ventrally situated- the heart is a pumping organ of circulatory system is found at the ventral side of the body.

Видео Chordata канала Dr. B. M. Singh