Phylum Chordata: Introduction to Phylum Chordata, Features of Chordates

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Introduction to Phylum Chordata

  • Phylum Chordata possess a bilaterally symmetrical body and presence of notochord is most distinguishing character that all animals belonging to this phylum.

  • It belongs to the Kingdom Animalia and includes all the vertebrates, i.e., animals with a backbone along with several invertebrates, i.e., organisms without a backbone.

Features of Chordates

Features of Chordates

Features of Chordates

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Notochord

  • Its main function is to support the nerve cord.

  • The vertebral column replaces the notochord in vertebrate animals.

  • Notochord further consists of a longitudinal rod that is made of cartilage and runs between the nerve cord and the digestive tract.

Dorsal Nerve Cord

A bundle of nerve fiber which connects the brain to the muscles and other organs.

Post-Anal Tail

The tail has skeletal muscles in some chordates which help in locomotion.

Pharyngeal Slits

  • These are the openings connecting the mouth and the throat.

  • The entry of water through the mouth is allowed without entering the digestive system.

  • This is the third largest phylum in the subphylum Vertebrata.

Division of Phylum Chordata

Division of Phylum Chordata

Division of Phylum Chordata

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Urochordata

  • It is also known as Tunicata because the body of an adult is enclosed within a tunic made up of cellulose like substance known as tunicin.

  • A dorsal ganglion in adults replaces the nerve cord present in larva.

  • The larva can move and undergoes metamorphosis.

  • For e.g. Ascidia, Salpa, Doliolum.

Cephalochordata

  • The tail is present throughout the life.

  • Progressive metamorphosis is shown.

  • The notochord is found throughout life.

  • For e.g. Lancelets possess the notochord and nerve cord throughout their life.

Vertebrata

  • These contain advanced chordates and have cranium around the brain.

  • A high degree of cephalization is observed.

  • They have a well-developed coelom (the principal body cavity in most animals).

  • The alimentary canal is complete.

  • For e.g. in Humans.