Cephalochordata (Gr., kephale, head; chorde, cord) is a sub-phylum within the phylum Chordata. The animals in this group are small, marine invertebrates. They are commonly called lancelets or amphioxi. Cephalochordates…
The sub-phylum Urochordata (Gr., uro, tail; chorde, cord) is a part of the phylum Chordata. The animals in this group are called sea squirts,or tunicates. These animals are very unique…
Phylum Hemichordata is generally considered the sister group of the phylum Echinodermata. The animals are marine deuterostomes. They are more or less worm-like, having the ancestral tripartite body of proboscis,…
The respiratory gases are taken during normal breathing extend into two regions between the respiratory tract i.e, the conducting zone and the respiratory zone. The wall of the respiratory transport…