Nart: Caddisfly Cases

Nature + Art = Nart

(Just for your future reference.)

Check this out:

Images via Cabinet Magazine (cabinetmagazine.org)

What you’re looking at is one very awesome aquatic macroinvertebrate (an invertebrate large enough to be seen without a microscope) called the caddisfly (Trichoptera) in its larval stage. You’ve probably seen caddisfly adults if you’ve ever been around a freshwater lake or stream at night: they’re nocturnal, delicate, mothy-looking insects that are easily attracted to light. According to NC State University’s entomology resources, they may go that entire period (a few weeks) without eating, which I think is pretty neato.

Depending on the species, caddisflies may spend several months to two years in the larval stage before pupating into adults. During that time, it uses a special silk secreted from glands near its mouth to build a protective case out of debris on the stream bed. It can then drag this amazing little piece of architecture around like a hermit crab carrying a shell. The larvae eat a variety of items depending on species, including detritus, algae, other tiny invertebrates, and – now this is super cool – some may ingest the eggs of the highly toxic rough-skinned newt (Taricha granulosa). This newt carries the lethal tetrodotoxin, and according to Brian Gall of Utah State University, caddisfly larvae could be a contributing environmental factor driving the potency of the tetrodotoxin poison.

Now, the photos above obviously aren’t your typical northern American stream bed debris. These incredible cases were constructed by caddisflies given precious metals and stones by French artist Hubert Duprat. As a boy, Duprat lived in the countryside and was a naturalist at heart, raising aquatic critters in aquaria and later developing an interest in geology. These two passions came together in experiments where caddisfly larva were given these new, precious materials with which to build their cases, and the above photos can give you a taste of the results. The original article is interesting and definitely worth a read – check it out at Leonardo online. The authors cite another interesting little article (you can download the PDF here) where Charles T. Brues makes an observation in 1930 that some caddisfly cases were constructed partially with tiny blue opals (which were far less numerous than grains of sand or other available materials) from the stream bed, suggesting that the larva were intentionally selecting the “attractive” stones. 

While most caddisflies won’t get to use materials considered so precious to humans, they will still go on to construct magnificent structures from stones, leaves, sticks, and more! The next time you’re by a stream, reach in a check under a few rocks – you may get to see one of these awesome little cases.

Image by David Funk of the Stroud Water Research Center (click pic to visit site)

Image by David Funk of the Stroud Water Research Center

Image via nwnature.net

Image via nwnature.net

Image via nwnature.net

Image via nwnature.net

As another neato fun-fact, the presence of species like caddisflies and mayflies play a role in indicating the health of a stream.

Click this great fact sheet to learn more about how macroinvertebrates can indicate stream health. Published by the Maryland Department of Natural Resources.

And this one will tell you which types of invertebrates indicate which types of stream health! Also Maryland DNR.

Thanks for reading!

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Posted on May 16, 2013, in Artsy, Fauna and tagged , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink. Comments Off on Nart: Caddisfly Cases.

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