Excerpts from Jim Conrad's
NATURALIST NEWSLETTER

Springtails

from the June 12, 2011 Newsletter issued from written at Mayan Beach Garden Inn 20 kms north of Mahahual, Quintana Roo, México
SPRINGTAILS

I have a favorite place up the beach where each morning I like to sit in the sand, lean against a tree trunk left by the last storm, dig my heels into the sand, and watch the early morning sun work its way up through clouds out over the water. The other day the tide was as high as it gets, so breaking waves wetted the sand and tossed-up Shoalgrass at my feet. It wasn't long before I realized that all over my feet and legs something very small was gnawing on me.

The skin on my feet and legs was heavily dusted with what looked like multitudes of cream-colored lice -- tiny creatures with softish-looking bodies with white legs, and black, pinprick eyes.

I started to nudge one with a finger but before my finger reached him he disappeared. Others did the same thing. They were JUMPING so quickly that my eyes and brain couldn't register their movement. In fact, now that I looked, when I waved my foot over the sand, thousands of these pale little beings sprang up like cooking popcorn.

I'd met critters like these before, so I knew that I'd dug my heels into sand and Shoalgrass working with springtails. You can see a springtail gnawing on my skin, and another one, about 1/6th of an inch long (4mm), grazing in wet Shoalgrass, at the top of this page.

The general body plan of a springtail is something like that of an open safety pin, with the lower pin part replaced with a tail-like appendage shaped like a fork, known as the "fercula." The springtail springs by snapping downward its furcula.

Springtails are not exotic animals. One expert describes them as the most abundant of all soil- dwelling arthropods. As well as being numerically superabundant, they're very diverse, with over 8000 species recognized worldwide.

For most of my life I've thought of springtails as forming one of the largest orders of insects. Nowadays with genetic sequencing most experts no longer regard them as insects. They're a distinct kind of life form arisen early during evolutionary history, and so far there's little agreement on where they belong on the Phylogenetic Tree of Life. Some experts regard them as constituting their own class. To put that in perspective, mammals form one class, and birds another.

What makes springtails so uninsectlike? For one thing they're wingless, but more profound is their "internal mouthparts." With Google I've tried to figure out how internal mouthparts work but can't. I do know that when springtails with their internal mouthparts gnaw on my skin it feels just as if they had external ones.