Diving-Bell Spider

Argyroneta aquatica.

The only spider that lives its whole life underwater. The female diving-bell spider traps a bubble of air inside a web hung between aquatic plants and spends her entire life living in it-- even mating and rearing offspring in it. When she leaves to hunt aquatic insects and minnows, hairs on her body trap a bubble of air around her abdomen, which acts like a naturla SCUBA tank. She will periodically grab some air from the surface to replenish her bubble-web, but most of the oxygen inside is naturally replaced through diffusion with the surrounding water.

I must say I'm not entirely happy with this piece. It's difficult to draw realistic bubbles with all their reflections and varying transparencies. Also, I didn't make the bubble-web quite big enough; it should be large enough for the spider to fit into comfortably. I'll probably go back and alter this a little later.