Sunday, April 7, 2013

Creature Feature: Springtails.

By request of one of our readers, we began looking stuff up on insect evolution. It's not covered too often, so the request was more than welcome. This led to our discovery of the oldest insect in the world, Rhyniognathus hirsti.


Wait a sec. What is that? Not in this blog's usual WTF way, but really, that fossil's hard to see. 
So here's the next best thing: a living fossil of an insect called a springtail.


Actually, we aren't even sure if springtails are insects. Some people think that they diverged from insects a while back, and thus deserve their own class (Entognatha). They have most of the right stuff- six legs, exoskeleton, etc. - but also have some traits that stick out. Unlike most insects, they never really metamorphose, and don't have external mouthparts. Also, as per the name, springtails possess a long structure in their rears (called a "furcula") that lets them jump. That last one doesn't keep them from being insects - it's just cool.

Springtails go way back. They go so far back that the first bug ever was first thought to be Rhyiella praecursor - a basal springtail. The same chert section with R. praecursor held the fossil first mentioned up above. This makes springtails among the first arthropods to ever walk on land. No wonder their taxonomy is confused.

Springtails may be creepy, but are they harmful? Yes and no. They are agricultural pests at worst, a title shared with many insects. They are, however, sensitive to herbicides and many other soil alterations. One springtail in particular is used as a model organism to test for potentially-toxic soil. See? They're not all bad.

If you wish to find springtails, well, this was an entry covering a whole class of bizarre little arthropods. Springtails are tiny, but can be found beneath leaves and in other humid places. As shown above, they are tiny, and frequently confused with fleas. They eat decaying matter and keep microoorganisms in check. Plus, they bounce; there's not much to hate, even though some people thing any creepy crawly is legitimately creepy.

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