Sting cells, also known as cnidocytes, are specialized cells that contain nematocysts in their cytoplasm. These cells are typically found in the body of Hydra, which is a small, freshwater, tentacled, tubular animal belonging to the phylum Cnidaria. The sting cells are used by the Hydra for defense and prey capture. When the tentacles come into contact with an organism, the nematocysts inside the sting cells are triggered to release a toxin, which can paralyze or kill the prey. Thus, sting cells are an important adaptation of the Hydra for survival.