Question

What are protochordates? Give their distinguishing features and classify them upto orders giving suitable examples?

Answer 1

Protochordata is not a proper taxonomic group . It consists of group of organisms that are invertebrates and are closely related to the vertebrates . This phylum is composed if phylum “Hemichordata”and the subphyla “Urochordata” and “Cephalochordata”.

Phylum Hemichordata •Hemichordata( Half chordates) are a small group of worm like marine animals .
•At present Hemichordata is treated as a separate non chordate phylum . They're closely related to echinoderms and chordates.

•General Characters:

•Habitat:
• Exclusively marine , solitary or colonial organisms.
• Symmetry:
• Body is soft , cylindrical, unsegmented,and bilaterally symmetrical.
• Body is divided into anterior ‘Proboscis’ middle ‘Collar’ and posterior ‘Trunk’.
• Level of organization:
• Triploblastic with organ system level of organization.
• Coelom:
• Enterocoelous Coelom.

They perform sexual dimorphism. Fertilization is external . Development is indirect.
Classification :
Class Enteropneusta:
Ex: Balonoglossus , Ptychodera.
Class Pterobranchia:
Ex: Rhabodpleura, Cephalodiscus.

It has 2 sub phyla namely :
1. Urochordata
2. Cephalochordata


You can refer to this link for more info:
http://www.shareyouressays.com/knowledge/three-important-subphyla-of-protochordates-that-are-divided-on-the-basis-of-character-of-notochord/92338