Air-breathing Diving Beetles range in size from 5-25mm. They can be found in still or flowing water, but prefer ponds.

The beetles can be easily identified by the way they 'swim' - synchronising their highly fringed hind legs.

Both adults and larvae are effective predators. Adults are adept at tearing larger prey into smaller pieces, while the larvae (known as water tigers) pierce and pump digestive juices into the prey, swallowing the liquefied remains.

Eggs are fertilised internally and laid, hatching into air-breathing aquatic larvae.