E-STAR - Student

Freshwater animals of the phylum Cnidaria and Class hydrozoa.
Hydra has a tubular, radially symmetric body up to 10 mm.
It has a simple adhesive foot called the basal disc.
There are gland cells in the basal disc, that are responsible for adhesive properties.
At the free end of the body is a mouth opening surrounded by one or few tentacles, each tentacle consists of specialized stinging cells called Cnidocytes.
Cnidocytes contain specialized structures called Nematocysts.
Nematocysts look like miniature light bulbs with coiled thread inside.