- Phylum hemichordata consists of a small group of worm-like marine animals.
- They have organ-system level of organization, bilaterally symmetrical, triploblastic and coelomate animals.
- The body is cylindrical and is composed of an anterior proboscis, a collar and a long trunk.
- Circulatory system is of open type, respiration takes place through gills and excretory organ is proboscis gland.
- Sexes are separate, fertilization is external and development is indirect.
Example- Balanoglossus and Saccoglossus.