Ever noticed these black beetles in ponds when it rains, they seem to be calm and then suddenly as you approach them they go crazy. Skittering about swimming fast like madcaps? That behaviour has earned them the name Whirly-gig beetles.
They're aqautic for their entire life, eggs are laid on submerged plants. Larvae live underwater and predate on mosquito larvae making them great pest control agents. The adults are also predaceous and usually swim on the surface When required they can dive like many aquatic insects with air bubbles trapped between wings for respiration. What they seem to be most studied for is aggregation, signalling and predator response. They release chemicals when disturbed which alert the others in an aggregation.
The coolest thing about them in my opinion however is that they're eyes are split. The lower half of both eyes are adapted for underwater vision and the upper half for vision in the air!
Some of those fluid mech / engineering types have also done some work on their swimming patterns and the waves they generate. So maybe the above image is interesting to them?