#diving beetles

[michaelnordeman]

Great diving beetle/Dytiscus marginalis/gulbrämad dykare (and what I believe is a Mud bithynia/Bithynia tentaculata/större snytesnäcka). Värmland, Sweden (22 April 2020).

[antiqueanimals]

Great diving beetle (Dytiscus marginalis)

The Entomologist's Text Book. Written and illustrated by John Obadiah Westwood. 1838.

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[starri-cosmikat]

earlier this week i fished up a water tiger out of the pond where i live and i held up a tadpole to his face so he could eat :) free meal for liddol guy

i dont have any water tiger pictures i took myself but they're the larvae of predacious diving beetles and theyre so sillay looking. when i first saw one i thought it was a dragonfly nymph at first but then i saw the huge as fuck mandibles

[pile-of-bugs]

One night I found a diving beetle. A big one! This is possibly a vertical diving beetle, but either way it's a predaceous diving beetle. Meaning they feed on other invertebrates and sometimes even small fish or tadpoles!

Here you can get an idea for the size. Almost 2 inches long I'd say, and pretty wide too. These beetles breathe underwater by storing air in the form of a flat bubble under their elytra - the hard parts on the back of a beetle that defines them as, well, a beetle. They can stay underwater without coming up for air for... uhm... sources give conflicting answers, but AT LEAST 10 minutes is agreed upon. Possibly hours! And all they need to refresh their air supply is a quick trip to the surface!

This particular beetle is a male - you can tell by the octopus-like suckers in the 2nd picture here. Diving beetles are SO smooth, the males need the suckers to hold on during mating. They're streamlined to travel through the water - they need to be fast to catch their prey and avoid predators!

Another adaptation of diving beetles is that their back legs are flat and covered in special strands that give them the shape of an oar. This is to help them swim of course, but it makes them slow on land. So you'll rarely ever see one outside the water. However, if their pond dries up or they need to escape through the air for whatever reason - they CAN fly as well!

Diving beetles are NOT dangerous for humans, and are pretty neutral on the pest/helper scale. They eat the larvae of a lot of annoying bugs, but may also choke a pond's fish and frog populations by eating their young too. You can safely scoop one up (I recommend a net, they're slippery as hell) and hold it. Even if they try to bite, their bite is too weak to hurt you.

WARNING: Just be CAREFUL not to confuse a diving beetle for a Giant Water bug - they can look similar at a glance, but Giant Water bugs absolutely WILL fuck you up and give you severe injuries!!! They also usually inhabit the same ecosystems, so be careful before grabbing a huge swimming bug out of a body of water! And, if you're keeping either as a pet, keep them in a tank separate from any other creatures you might have (unless they're intentionally there as food).

[symbiotic-science]

A mating war in diving beetles has stopped the evolution of species

In nature, male attempts to mate with females can be so extreme that they can harm the females. Such negative impacts of mating interactions have been suggested to promote the emergence of new species under some circumstances. Surprisingly, one type of diving beetle species now shows that this conflict between the sexes can instead lead to an evolutionary standstill in which mating enhances traits in males and fosters counter-adaptations in females, preventing the formation of new species.

In nature, male attempts to mate with females can be so extreme that they can harm the females. Such negative impacts of mating interactions have been suggested to promote the emergence of new species under some circumstances. Surprisingly, one type of diving beetle species now shows that this conflict between the sexes can instead lead to an evolutionary standstill in which mating enhances traits in males and fosters counter-adaptations in females, preventing the formation of new species.

This unconventional, yet potentially impactful alternative outcome of sexual conflict was described by scientists from Arizona State University (U.S.), the University of Copenhagen (Denmark), Lund University (Sweden) and the Swedish Museum of Natural History in Stockholm. Their findings were published today in the journal Proceedings of the Royal Society B.

"Our study challenges previous ideas of sexual conflict as an engine of speciation," says Lars L. Iversen, a researcher at Arizona State University's Julie Ann Wrigley Global Institute of Sustainability. "Usually, females evolve ways to escape the mating harassment from males, and this could initiate the evolution of new species. Here, we document an alternative outcome—that sexual conflict instead prevents populations from diverging from each other and becoming new species."

In many diving beetles, males are equipped with crafted suction cups on their front legs that attach to the backs of females during mating. This grasping ability has become so effective that females can be harmed under high mating pressure, lasting up to many hours for each mating attempt. As a consequence, some females have developed a rougher back that is more difficult for male attachment.

[terra-formed]

#inktober day 4: underwater Just a concept sketch of a spread that I hopefully can work on more later. Ponds here are full of so much interesting life! I love looking for diving beetles, tadpoles, and dragonfly nymphs. 🐸🐢💚

[michaelnordeman]

Great Diving Beetle/gulbrämad dykare. Värmland, Sweden (April 13, 2025).

[antiqueanimals]

Great diving beetle (Dytiscus marginalis). The Natural History of Insects; In Two Volumes. Vol. II. 1835.

Internet Archive