ABSTRACT
Other animals do not seem to age at all, even though their typical lifespans are short because of predation and other hazards.
Hydra are primitive invertebrates with radial symmetry-a mouth on a stalk, surrounded by oversized tentacles, living in ponds and streams. Under a magnifying lens, they look a bit like (but are unrelated to) tiny squids. With their tentacles, they snare “water fleas” and other tiny crustaceans, on which they feed. Hydra have been studied for four years at a time, starting with specimens of various ages collected in the wild and they do not seem to die on their own or to become more vulnerable to predators or disease with age [46].
