Aphelocheirus, a longlasting diver

The story of a well-equipped swimmer.

Transcript

Picture yourself swimming in a shallow brook.

[Southern Indian river soundscape with goats fades in]

Several centimeters of clear water above and below you offer you plenty of hunting grounds. Your round flat body is perfect to chase down preys. You are a small aquatic bug, and an expert diver.

Hi and welcome to the Insect Insights, chill insect stories to relax and wonder, available wherever podcasts are. If you like this podcast, you can subscribe, leave a review and even an insect question, on spotify or on the website. I am Max, your host, and I hope you are ready to dive into insect knowledge for another insight!

Many insects dwell in fresh water like you, Aphelocheirus. Not so many can live permanently under the surface, without ever needing to go up to breath. That’s the mark of the more sophisticated divers, and you are certainly part of that crew.

Of course, like all adult insects, you do need to breath air, with gaseous oxygen. Unlike many animals, you cannot directly breath the oxygen present in the water., dissolved. Your tracheal system, the network of air tubes in your body, work only with gas. Fortunately for you, little bug, you have a way to breath gaseous oxygen even underwater. You simply carry a bubble with you at all time.

It may sound easy. It may sound simple. Afterall, many insects, and other arthropods, just get air from the surface and carry it down the water to use as breathing supplies. The problem for these mere occasional divers is that the bubble does not last. It either shrinks down as the nitrogen dissolves itself in the water, or all the oxygen runs out. And then, they have to go all the way up again for a refill, ha!

Nothing of that for you. Your precious bubble is permanent. Thanks to a dense carpet of extremely thin hydrophobic setae on your body, the wetting is kept at bay, securing a stable air-water interface. It also gives you a very stylish look, with this thin layer of air covering the lower part of your body looking like a silvery belly.

So, you have your permanent air storage. Nice! But what about oxygen running out? That would be a shame. Well, the good thing is that your little air pocket is able to capture the oxygen dissolved in the water, making it available to you in gaseous form. As you consume the oxygen of your bubble, it’s able to get more from the water, at a rate sufficient to meet your needs.

This little bubble you sustain, and the gas exchanges it allows, is called a physical gill. It is the secret to your aquatic longevity.

Sources

Seymour, R. S., Jones, K. K., & Hetz, S. K. (2015). Respiratory function of the plastron in the aquatic bug Aphelocheirus aestivalis (Hemiptera, Aphelocheiridae). Journal of Experimental Biology, 218(18), 2840–2846. https://doi.org/10.1242/jeb.125328

Sites, R. W., Arunachalam, M., & Sundar, S. (2011). A new species of Aphelocheirus (Hemiptera: Heteroptera: Aphelocheiridae) from southern India. Zootaxa, 2916(1), Article 1. https://doi.org/10.11646/zootaxa.2916.1.2