Vertebrata, Biology

VERTEBRATA

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

S.No.

Character

Agnetha

Gnetha

 

1

 

True Jaws

 

Absent

 

Present

2

Paired apendages

Absent

Present

3

Semi circular canal in internal ear

2

3

4

Nostril

1

2

 

1.

AGNETHA

 

Agnetha is divided into two parts -

1. Ostracodermi

2. Cyclostomata

(I)      OSTRACODERMI

  • First vertebrate. Greatly armoured. All fossils.

EXAMPLES -   Cephalospis

(II)     CYCLOSTOMATA

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.

EXAMPLES -

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







Related Discussions:- Vertebrata, Assignment Help, Ask Question on Vertebrata, Get Answer, Expert's Help, Vertebrata Discussions

Write discussion on Vertebrata
Your posts are moderated
Related Questions
describe each and every step in nutrition in animals?

give detail account of modes of locomotion in protozoa and describe various type of asexual reproduction in protozoa

why brains can''t be transplant?

Explain the Toxicity of Vitamin D? The adverse effects of high vitamin D intakes include hypercalciuria (excessive urinary calcium excretion) and hypercalcaemia (high concentr

Determine the groups of soil organisms The soil organisms are classified into two broad groups viz. soil flora (related to plants) and soil fauna (related to animals) which ar

Carbohydrates These form about 1%part of protoplasm, they are comparatively simpler compounds of carbon, hydrogen and oxygen in the ratio 1:2:1 The ratio hydrogen to oxygen is

Determine the meaning of Response cost This is a type of punishment in which the subject has to return back the token (positive reinforcement) earned earlier if the subject dis

You are interested in plant life history evolution, you come across a population of the California poppy that i spolymorphic (mixed) for both iteroparous ans semeparous individuals

Radial Artery (RA) :  Patency of RA is less than that of Ih4.A but much superior to a venous graft. One of the studies showed 90 per cent patency at 13 months and 83

DISORDER S OF FEMALE REPRODUCTIVE SYSTEM - (i)         Sterility (ii )     Menstrual irregularity - This may be amenorrhea (absence of M.C.) or excessive bleeding (