How healthy is the water? 12 How healthy is the water? Why count creatures? You can use invertebrates to tell how healthy water is. Ones that breathe through gills like Dragonfly Nymphs find it hard to live in polluted water as there is less oxygen. Invertebrates that use an air bubble such as water beetles can cope with less oxygen in the water as they get their air from the surface. Dragonfly nymph Type of Pond Animal Quality Index Score Cased caddis fly larvae Score 10 if found Dragonfly larvae Score 10 if found Alderfly larvae Damselfly larvae Caseless Cadisfly larvae Mayfly larvae Score 5 if found Water beetles/ larvae Score 5 if found Waterbugs Pond skaters Water shrimps Water snails Score 1 if found Hoglouse Score 1 if found Worm like animals Total score= Water boatman What does your score mean for the water? Score 31 or more Very healthy Score 6-30 Quite healthy Score 0-5 Not very healthy