Hydra, or Phylum Colenterata was discovered in 1740. It is a small animal organism found under lily pads in ponds, sluggish streams, and lakes. When it is seen in the water, it looks like a piece of thread about 1 cm. to 1 in. long floating in the water. It uses its tentacles at the end of its hypostome to insert toxins and to stun prey, after the prey is stung, it then uses the tentacles to guide the animal or plant towards its mouth. They feed on small plankton, organisms, freshly hatched brine shrimp, and especially micro crustaceans. They reproduce sexually using their gonadal cells. They reproduce asexually by budding. There are two other types of Hydra, one of these is the Green Hydra, or Chlorhydra Viridissima, and the gray and brown hydras belong to the Genus Pelmatohydra. Hydra is separated into 5 major parts, those are: the tentacles, the body column, the basal disk, the hypostome, and the mouth. If growing is occurring there will be an extension called a bud growing somewhere near the basal disk.
The water pH level can either be very basic to very acidic, or it can be neutral. Depending on the level will depend on the growth of the Hydra. The scale measures from pH 1 to pH 14. Neutral is pH 7, extremely acidic is pH 1, and extremely basic is pH 14. It measures the acidity or base of the water. The strength of an acid depends on how many hydronium ions it produces when it dissolves to form a solution. More hydronium ions produced, the stronger the acid. The strength of a base depends on how many hydroxide ions it produces when it dissolves to form a solution.
Regeneration occurs when an organism is damaged or cut, and it has the ability to repair that damage and make a complete organism again on its own free will. The Swiss naturalist Abraham Trembley proved that if the hydra was cut in two or more places, each piece would grow into a complete organism again. He also proved that if two or more hydra were grafted together they would form a single organism. Planaria have this same ability, depending on where it is cut will depend on how many heads or tails it will grow.