Phylum – Cnidaria
Habit and Habitat: Many members of the phylum live in worldwide in fresh water, drain, canal, river, lake, stream etc. But maximum are marine species. They are of different colour, shapes and sizes; they are the beauty of sea they are attached with floating wood, leaves or something else or free swimming.
Fig: Animals of Different Phyla
Some species are free living and some are colonial. As: Hydra (fresh water animal) Jelly fish (Marine water animal) and Corals (Marine).
- They are two layered animals; body is formed of two embryonic cell layers ectoderm and endoderm. Between these two layers there is a non-cellular layer called mesoglea.
- A body cavity named coelenteron or gastrovascular cavity takes part both in digestion and water circulation.
- In the ectoderm there are specialized cnidoblast cells. Example: Hydra
Example: Hydra vulgaris, Aurelia aurita.