Phylum Cnidarian (coelenterate) the body wall and nematocysts; alternation of generations; maintenance functions

Phylum coelenterata is divided into three classes: Class 1. Hydrozoa (1) Hydrozoa are solitary and fresh water or mostly colonial and marine, sessile and free-swimming forms. (2) They exhibit tetramerous or polymerous radial symmetry (3) Body wall consists of an outer ectoderm and an inner endoderm separated by a non–cellular gelatinous mesogloea.

Reference:

  • Miller, A.S. and Harley, J.B., 1999 & 2002 . Zoology , 4th and 5th Edition (International), Singapore:McGraw Hill.