obelia is a genus of hydrozoa, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages

animal asexually biological biology cavity cell cnidocytes dna education educational epidermis freshwater gastrodermis gastrovascular gastrozoid gonozooid histology hydroid hydrozoa hydrozoan jellylike mammal mammalian marine medicine medusa mesoglea microscope microscopic nucleus obelia ocean polyp research science scientific sea tentacle tissue university zoological zoology