Question

write the classification of chordates​

Answer 1

urochordata, cephalochordata, vertebrates

Answer 2

Classifications of Chordata:

1. Urochordata

(i) Adults are generally sedentary (fixed to substratum),

(ii) This sub-phylum is also called Tunicata because the adult body is enclosed within a leathery test or tunic formed of a cellulose-like organic substance termed tunicin.

(iii) The notochord is only present in the tail of the larva and disappears in the adult,

Examples:Ascidia, Ciona, Doliolum, Salpa, Botryllus

2. Cephalochordata

(i) Both the adult and larva are motile,

(ii) The notochord extends up to anterior end of the body hence this subphylum is named,

(iii) The notochord persists throughout life.

3. Vertebrate or Craniata:

(1) These are advanced chordates that have cranium (brain box) around brain.

(2) Notochord is only present in the embryonic stage; it is replaced by a cartilaginous or bony vertebral column in the adult forms.

(3) There is very high degree of cephalization (formation of head).

Example:

Petromyzon (Lamprey), Myxine (Hagfish).