Give abrief account on Protochordates.
Answers
Protochordate, any member of either of two invertebrate subphyla of the phylum Chordata: the Tunicata (sea squirts, salps, etc.) and the Cephalochordata (amphioxus). Like the remaining subphylum of the chordates, the Vertebrata, the protochordates have a hollow dorsal nerve cord, gill slits, and a stiff supporting rod, the notochord, the forerunner of the backbone. The protochordates differ chiefly from the vertebrates in not having a backbone. Recent protochordates are thought to have evolved from the same ancestral stock as that which gave rise to the vertebrates.
Answer:
•Protochordates are commonly called lower chordates.
•They lack a head and a cranium, so they are also known as Acraniata.
•Protochordates consists of three sub-phyla based on the property of notochord. They are Hemichordata, Urochordata and Cephalochordata.
•Body is stout and unsegmented, and has a worm–like or vase–like.
•They are bilaterally symmetrical and triploblastic.
•They have organ-system level of organization.
•All feed on microorganisms and debris