Vertebrata, Biology


It is divided into two parts -        1. Agnetha                    2. Gnetha








True Jaws






Paired apendages




Semi circular canal in internal ear











Agnetha is divided into two parts -

1. Ostracodermi

2. Cyclostomata


  • First vertebrate. Greatly armoured. All fossils.

EXAMPLES -   Cephalospis


Body eel like. Mouth sucker type.  Ectoparasite.

Gills 5-16 pairs. Pineal eye present.

Unicellular shin glands present.

Scales absent. Sanguivorous.

On tongue horny teeth present.


1.       Petromyzon                                - lamprey, lampredin present, 7 pairs gills, larva is ammocoet for seven years, living fossil

2.       Myxine                                        - Hag fish, lips as of old lady, bisexual, development direct


Note :- Before pisces & after cyclostomata placodermi is a group of extinct fishes (jawed).

These are most primitive fishes. Example- climatius

2.      GNETHA

Gnetha is divided into 5 classes -

1. Pisces

2. Amphibia

3. Reptilia

4. Aves

5. Mammalia

Posted Date: 10/1/2012 1:46:08 AM | Location : United States

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