Jan Hamrsky / Diving beetle (Colymbetes fuscus) close up head portrait. Europe, June. Controlled conditions.

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) portrait, Europe, September, controlled conditions

Jan Hamrsky / Diving beetle larva (Platambus maculatus), Europe, February, controlled conditions

Will Watson / Head on view of Diving beetle (Cybister lateralimarginalis) resting among Bladderwort (Utricularia sp.) captive conditons, Belgium.

Will Watson / Diving beetle (Graphoderus cinereus) among Bladderwort (Utricularia sp.), captive, Belgium

Robert Thompson / Great diving beetle (Dytiscus marginalis) larva, Montiaghs Moss NNR, County Antrim, Northern Ireland, UK.

Will Watson / Diving Beetle (Rhantus exsoletus), Moccas Park National Nature Reserve, Herefordshire, England.

Will Watson / Diving bettle (Agaubus bipustulatus) taking air, Captive, Carmarthenshire, Wales, UK. July.

Will Watson / Diving Beetle (Colymbetes fuscus) resting on submerged log, captive, Herefordshire, England.

Will Watson / Diving beetle (Graphoderus cinereus) with Ciliates, Moccas Park, National Nature Reserve, Herefordshire, England, UK. Vulnerable species.

Will Watson / Diving beetle (Graphoderus cinereus) with Ciliates, Moccas Park, National Nature Reserve, Herefordshire, England, UK, June. Vulnerable.

Will Watson / Mud dweller beetle (Ilybius ater) at rest on Hornwort (Ceratophyllum demersum), Carmarthenshire, Wales. Captive.

John Abbott / Predacious diving beetle (Cybister fimbriolatus) swimming Williamson County, Texas, USA Controlled conditions. October

John Abbott / Predaceous diving beetle (Thermonectus basillaris), Tuscaloosa County, Alabama, USA Controlled conditions. July

Jan Hamrsky / Diving beetle (Platambus maculatus), Europe, August. Controlled conditions.

Jan Hamrsky / Diving beetle (Colymbetes fuscus), Europe, June. Controlled conditions.

Jan Hamrsky / Diving beetle larva (Cybister lateralimarginalis), Europe, May. Controlled conditions.

Jan Hamrsky / Diving beetle larva (Cybister lateralimarginalis), Europe, May. Controlled conditions.

Jan Hamrsky / Diving beetle (Cybister lateralimarginalis), Europe, May. Controlled conditions.

Jan Hamrsky / Diving beetle (Cybister lateralimarginalis), Europe, May. Controlled conditions.

Will Watson / Black belly diving beetle (Dytiscus semmisulcatus), Cheshire, England, UK, July. Captive.

MYN / Niall Benvie / Great diving beetle (Dytiscus marginalis) Burgundy, France. April.

MYN / Niall Benvie / Great diving beetle (Dytiscus marginalis) Burgundy, France. April.

MYN / Niall Benvie / Great diving beetle (Dytiscus marginalis) underwater, Burgundy, France. April.

MYN / Niall Benvie / Great diving beetle (Dytiscus marginalis) underwater, Burgundy, France. April.

MYN / Niall Benvie / Great diving beetle (Dytiscus marginalis) Burgundy, France. April.

MYN / Paul van Hoof / Great diving beetle (Dytiscus marginalis) larva, June, The Netherlands, Meetyourneighbours.net project

Will Watson / Water beetle (Rhantus suturalis) Shropshire, England. Captive. May 2014.

Jussi Murtosaari / Great diving beetle (Dytiscus marginalis) diving in aquarium, Kumlinge, Ahvenanmaa / Aland Islands Archipelago, Finland. November

Jussi Murtosaari / Great diving beetle (Dytiscus marginalis) in aquarium, Kumlinge, Ahvenanmaa / Aland Islands Archipelago, Finland. November

Jussi Murtosaari / Great diving beetle (Dytiscus marginalis) Photographed in aquarium, Kumlinge, Ahvenanmaa / Aland Islands Archipelago, Finland. November

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) larva, head detail. Europe, June, controlled conditions.

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) larva breathing at surface, Europe, June, controlled conditions.

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) larva breathing at surface, Europe, June, controlled conditions.

Jan Hamrsky / Water beetle (Laccophilus sp) taking air at the surface, January, Europe, controlled conditions.

MYN / Niall Benvie / Field studio composite of amphibians, fish, and aquatic invertebrates from Preporche, Burgundy, France, April. meetyourneighbours.net project

MYN / Krista Schlyer / Diving beetle (Dytiscidae sp.) larva, Lily Lake, Estes Park, Colorado, USA. August. Meetyourneighbours.net project.

Ann & Steve Toon / British diving beetles (Dytiscus sp.), museum specimens, Tyne and Wear Archives and Museums

Will Watson / Female Great diving beetle (Dytiscus circumflexus) at surface to breath, UK, captive.

Will Watson / Female Great diving beetle (Dytiscus circumflexus) view of underside with cloacal sperm plug from previous mating, UK, captive.

Will Watson / Male Great Diving Beetle (Dytiscus marginalis) taking in air, captive, Essex, England.

Will Watson / Female Great diving beetle (Dytiscus circumflexus), resting on Hornwort, captive, UK.

Will Watson / Female Great diving beetle (Dytiscus circumflexus), resting on Hornwort, UK, captive.

Will Watson / Female Black Belly (Dytiscus semisulcatus) at surface for air, Llyn Heilyn, Radnorshire, Wales.

Jan Hamrsky / Lesser diving beetles (Acilius sulcatus) mating pair, Europe, May, controlled conditions

Jan Hamrsky / Lesser diving beetles (Acilius sulcatus) mating pair, Europe, May, controlled conditions

Jan Hamrsky / Lesser diving beetles (Acilius sulcatus) mating pair, Europe, May, controlled conditions

Jan Hamrsky / Lesser diving beetle (Acilius sulcatus) male, Europe, May, controlled conditions

Jan Hamrsky / Lesser diving beetle (Acilius sulcatus) refilling its air supply by the surface, male, Europe, May, controlled conditions

Jan Hamrsky / Diving beetle (Agabus sturmii) refilling its air supply by the surface, Europe, May, controlled conditions

Jan Hamrsky / Diving beetle (Agabus sturmii) Europe, May, controlled conditions

Jan Hamrsky / Diving beetles (Graphoderus bilineatus) female (right) and male (left) Europe, August, controlled conditions

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) male, Europe, August, controlled conditions

Jan Hamrsky / Diving beetles (Graphoderus bilineatus) female (left) and male (right) Europe, August, controlled conditions

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) refilling the air supply by the surface, female, Europe, August, controlled conditions

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) refilling the air supply by the surface, male, Europe, August, controlled conditions

Jan Hamrsky / Diving beetle (Graphoderus bilineatus) cleaning its antennae, female, Europe, August, controlled conditions

Jan Hamrsky / Diving beetle larva (Graphoderus bilineatus) Europe, June, controlled conditions

Jan Hamrsky / Great diving beetle larva (Dytiscus marginalis) head detail, Europe, June, controlled conditions

Jan Hamrsky / Great diving beetle larva (Dytiscus marginalis) with dragonfly nymph prey, Europe, June, controlled conditions

Jan Hamrsky / Great diving beetle larva (Dytiscus marginalis) with dragonfly nymph prey, Europe, June, controlled conditions

Jan Hamrsky / Great diving beetle larva (Dytiscus marginalis) breathing by the water surface, Europe, June, controlled conditions

Wild Wonders of Europe / Lundgren / Water beetle (Dytiscidae) swimming just under the surface at night, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Water beetle nymph (Dytiscidae) attacking a large dragonfly nymph, Danube Delta, Romania, June. Ph

Wild Wonders of Europe / Lundgren / Water beetle (Dytiscidae) nymph, Danube Delta, Romania, June.

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) female, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) hiding in freshwater red algae (Batrachospermum moniliforme) Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) female, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) hind oar-like leg detail, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) refilling its air supply under the wing cases, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) female, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) refilling its air supply under the wing cases, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle (Dytiscus marginalis) refilling its air supply under the wing cases, Europe, September, controlled conditions

Jan Hamrsky / Great diving beetle larva (Dytiscus marginalis) feeding on tadpole, Europe, May, controlled conditions

Will Watson / River diving beetle (Oreodytes sanmarkii) resting on a leaf, Humber Brook, Herefordshire Plateau, England, UK. October. Controlled conditions using microscopy.

Will Watson / River diving beetle (Nebrioporus elegans) portrait, River Wye SSSI, Herefordshire, England, UK. September. Captive. Focus stacked and retouched.

Will Watson / Diving beetle (Laccophilus minutus) resting on pebbles underwater, Bodenham Lake Nature Reserve, Herefordshire, England, UK. September. Controlled conditions using microscopy.

Joel Sartore / Photo Ark / Two Green diving beetles (Cybister sp.) portrait, Melbourne Zoo. Captive.

Edwin Giesbers / Great diving beetle (Dytiscus marginalis) nymph at water surface, the Netherlands. Controlled conditions

Edwin Giesbers / Diving beetle (Rhantus exoletus) nymph, the Netherlands. Controlled conditions

Edwin Giesbers / Diving beetle (Rhantus exoletus) nymph, the Netherlands. Controlled conditions

Edwin Giesbers / Predatory Diving beetle (Hydaticus seminiger) below water surface, the Netherlands. Controlled conditions

Edwin Giesbers / Diving beetle (Rhantus exoletus), the Netherlands. Controlled conditions

Edwin Giesbers / Diving beetle (Rhantus exoletus) below water surface, the Netherlands. Controlled conditions

Edwin Giesbers / Two Diving beetles (Rhantus exoletus) below water surface, the Netherlands. Controlled conditions

Will Watson / Male Highland Great diving beetle (Dytiscus lapponicus) on surface of water, Darnaway Estate, Highlands, Scotland, UK. May. Focus stacked. Captive.

Will Watson / Male Highland Great diving beetle (Dytiscus lapponicus), dorsal view, on water surface, Darnaway Estate, Highlands, Scotland, UK. May. Focus stacked. Captive.

Will Watson / Male Highland Great diving beetle (Dytiscus lapponicus) in water, underside, Darnaway Estate, Moray, Scotland. May. Focus stacked. Captive.

Will Watson / Male Highland Great diving beetle (Dytiscus lapponicus) on surface of water, Darnaway Estate, Highlands, Scotland, UK. May. Focus stacked. Captive.

Emanuele Biggi / Predatory water beetle (Dytiscus sp.) larva waiting in ambush, Beigua Regional Park, Italy. June.

Will Watson / Diving beetle (Acilius canaliculatus) swimming, a rare species in the UK, Shawbury Heath, Shropshire, England, UK. Controlled conditions. May.

Will Watson / Black-bellied great diving beetle (Dytiscus semisulcatus) female, Breconshire, Wales, UK. Controlled conditions. Focus stacked

Emanuele Biggi / Predaceous diving beetle (Dytiscidae) larva with Common frog (Rana temporaria) tadpole prey in a pond, Northern Apennines. Beigua Geopark, Italy, May.

Emanuele Biggi / Predaceous diving beetle (Dytiscidae) larva with Common frog (Rana temporaria) tadpole prey in a pond, Northern Apennines. Beigua Geopark, Italy, May.

Franco Banfi / Lesser diving beetle (Acilius sulcatus) larvae. Lago Nero, Pistoia, Tuscany, Italy.

Franco Banfi / Two Lesser diving beetle (Acilius sulcatus) mating, Lago Nero, Pistoia, Tuscany, Italy.