Wednesday, July 29, 2020

Animal Kingdom - Notes | Class 11 | Part 12: 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 & 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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