Tuesday, December 14, 2010

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).

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