Wednesday, July 29, 2020

Animal Kingdom - Notes | Class 11 | Part 6: Chordata up to Subphylum Vertebrata

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 and single

Ventral, solid and double

3.      Pharyngeal gill slits present

Absent

4.      Ventral heart

Dorsal heart (if present)

5.      A 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).

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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