In a backyard pond in Irvine, Orange County, CA. 3/7/09.
Size 1-5 mm; One of the few Cnidarians that live in freshwater, hydra are found in most streams and lakes. They cannot tolerate salt water. They are usually found on the undersides of leaves, sticks and stones resting on the bottom. There are about a dozen species, with only two reported from Orange County.