Hydras are small, freshwater organisms belonging to the phylum Cnidaria. They are known for their simple body structure, which typically includes a tubular body and tentacles that surround their mouth. Hydras can regenerate lost body parts, making them a subject of interest in scientific research. These creatures are usually found in ponds and streams, where they attach themselves to surfaces using a structure called a basal disc. Hydras primarily feed on small aquatic animals, such as zooplankton, by capturing them with their stinging cells, known as nematocysts.