1. Hernichordata
2. Cephalochordata
3. Urochordata

The prochordates do not have a Cranium or skull. They are referred to as Acrania.

No, jelly fish and star fish are radial symmetry the body parts are arranged around the central axis. If we cut through central axis in any direction it can be divided into two similar halves. But cat fish is not a radial symmetry.

The respiratory organs of amphibians are gills, skin, bucco - pharynx and lungs.

Due to the presence of two layers in the body wall of coelenterates. So they are called as diploplastic animals.

In the jelly fish its tentacles bear stinging cells called nematocysts.

Taxonomy is the theoretical study of classification including its basic principles, procedures and rules.

On the basis of position of notochord, the different prochordates are classified as follows.
1. Sub-phylum Hemichordata : The notochord is persistant as the stomochord in the anterior region of the animal. e.g., Balanoglossus.
2. Sub-phylum - Cephalochordata : The persistent notochord extends forward beyond the brain. e.g., Amphioxus.
3. Sub-phylum - Urochordata : The notochord is confined to the tail region of the larva, e.g., Asicidian.

1. Fishes are poikilothermic, aquatic vertebrate with jaw.
2. Body is streamlined and differentiated into head, trunk, and tail.
3. Locomotion is by paired and median fins.
4. Body has covering of scales.
5. Respiration is performed by gills. Gill slits are 5-7 pairs.

1. Arthropoda is an ancient and the largest phylum with number of species.
2. Insects, spiders, crabs, shrimps, butterflies, millipedes, centipedes and scorpions are arthropods.
3. Body is divisible into head, thorax and abdomen.
4. The coelomic cavity is filled with haemolymph
5. They have open circulatory system
6. Excretion occurs through malphigian tubules in insects and through green glands in crabs and prawns.

The prochordates are considered as the forerunners of vertebrates. They are classified into Hemichordata, cephalochordata and urochordata.
Hemichordata:
Hemichordata are marine organisms without back bone. They mostly remain as tubiculous forms. The body is soft, vermiform, unsegmented, bilaterally symmetrical and triploplastic.
Eg: Balanoglossus

Cephalochordata:
Cephalochordates are small fish like marine chordates with unpaired dorsal fins. The notochord extends throughout the entire length of the body.
Eg: Amphioxus

Urochordata:
The adults are mostly degenerate and are sessile forms. The body is enveloped by a tunic or test.
Eg: Asicidian