Can you describe the eating behaviour of Hydra?

Question

Please use as much detail as possible. Thanks.

Answer 1

They contain tentacles with special stinging cells called nematocysts. These nematocysts come in a variety of structures. They are activated by touch and can only be used once. They function in protecting the animal and helping capture its food. The cnidocytes are the cells that produce the nematocysts. These cells along with their tentacles will capture their prey and stuff it into their mouth.
There the food enters a central cavity called the Gastrovascular cavity. Digestion takes place here and the contents are absorbed by the endodermal cells. The undigested food is expelled through its mouth. This is considered a two way digestive process.

Answer 2

Hydra are easily maintained in a freshwater aquarium and do not need filtration or aeration systems. In any freshwater aquarium, ammonia will tend to accumulate, so the water should be changed every few weeks. Always use freshly collected pond water or rain water; chlorinated tap water will usually kill hydra as well as the smaller creatures upon which they feed. Hydra are voracious and will feed and reproduce rapidly if given an abundant supply of food. Small crustaceans, such as Daphnia and Cyclops are ideal prey, but a large hydra population will deplete crustaceans rapidly. If you have a lake or river in the vicinity, small crustaceans such as these can be readily collected in large numbers with the aid of a plankton net . In the absence of prey, hydra can obtain a certain amount of food by absorbing organic molecules directly across the ectoderm. If food is unavailable, reproduction will cease and hydra will use their own tissues for energy, shrinking to an indefinitely small size before they finally die.