Hydra

HYDRA

PHYLUM CNIDERIA
PHYLUM COELENTERATA

(coel meaning 'hollow' and enteron meaning 'gut')

Hydra through the microscope.

Morphology:

v  one opening (mouth)

v  hollow body

v  main cavity of the hydra's body is the digestive cavity

v  consists of two layers: ectoderm (outer – protective epithelium) and endoderm (inner – primarily a digestive epithelium)

Habitat: Hydras live in freswater lakes, ponds and streams. They attatch to rocks and water plants with a sticky secretion from disklike base.
Movement/Locomotion: 

v  gliding on the base due to a creeping ameboid movement of basal cells.

v  bending over and attaching to the substrate with the mouth and tentacles and releasing the foot (which usually provides attachment), then the body bends over and makes a new place of attachment.

Eating: Do not chase prey but poisons it. It leaves its tentacles trailing and when they are brushed, send out a shower of poisonous numbing thread capsules (weapons that arm the body).