4. ANIMAL KINGDOM

PHYLUM CHORDATA

It includes animals with notochord, dorsal tubular nerve cord and pharyngeal gill slits.

Notochord is a flexible rod located in the mid dorsal line between the alimentary canal and the nerve cord in the embryo.

Differences between Chordata and Non-Chordata

Chordata	Non-Chordata
1. Notochord is found in the embryonic stage.	Absent
2. Central nervous system is dorsal, hollow & single.	Ventral, solid & double
3. Pharyngeal gill slits present.	Absent
4. Ventral heart.	Dorsal heart (if present)
5. Post-anal part (tail) is present.	Absent

Phylum Chordata is classified into 3 subphyla: Urochordata, Cephalochordata & Vertebrata.

PROTOCHORDATA (ACRANIATA)

Urochordata (Tunicata)

Cephalochordata

· Notochord present only in larval tail.

· Body is covered by test made up of tunicin.

· Exclusively marine.

· Hermaphrodite.

· E.g. Ascidia, Salpa, Doliolum.

· Notochord from head to tail region and is persistent throughout the life.

· Fish-like body.

· Exclusively marine.

· Sexes are separate.

· E.g. Branchiostoma (Amphioxus or Lancelet).

Ascidia

VERTEBRATA (CRANIATA)

· Possess notochord during the embryonic period.

· Notochord is replaced by a cartilaginous or bony vertebral column in the adult.

· Ventral muscular heart.

· Kidneys for excretion & osmoregulation

· Paired appendages (fins or limbs).

CLASSIFICATION OF VERTEBRATA

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Animal Kingdom - Notes | Class 11 | Part 12: Chordata up to Subphylum Vertebrata