Popcorn critters on ice

I knocked the snow and ice off a baby holly tree in a pot and brought it inside to look for a springtail. Within minutes, hopping specks of life were taking over my desk, and I was trying to trap them with plastic bottles before they got in the computer.

A BC winter is ideal for springtails. They love the cold and need the moisture. When the insects and spiders go into hiding, the springtails are just getting going. In my yard, they're on the shrubbery (shake a branch over a bowl, and they fall in), they're in the flower pots, under the planters, in the moss, on rotting wood and soggy soil. And in the birdhouse. But they're not limited to our mild climate; anywhere there is air and moisture, there are springtails, even deep in caves and on glaciers, even in salt water. Their fossils are

... among the oldest known records of terrestrial animals. (Bellinger, P.F., Christiansen, K.A. & Janssens, F. 1996-2011)

They're not insects, although they have six legs like insects. They're probably more related to crustaceans like shrimp and copepods (Janssens), and started out in an aquatic environment. Some still live in the water; all are equipped to walk on water. If you're looking at a moving reddish dot, not taking your eyes off it for even a moment; maybe you've got the camera focused on it; and then suddenly it's not there - you didn't see it go, it just ceased to exist in that spot - and then you find it a few inches away, calmly scratching its nose or taking a drink, you've found a springtail. They don't need the wings they never have; they've got a faster means of propulsion.

Within a dozen steps from my back door, I can find at least four species of springtails.

Globular springtail, Dicyrtomina ornata Orchesella cincta. Thanks, Frans!.

Slender springtail, Entomobrya nivalis, I think.

A green E. nivalis, on frozen, rotting bark.

Dicyrtomina minuta forma ornata comes in a variety of patterns and colours.

Entomobrya clitellaria, forma albocinta. I found this one almost 2 years ago, but its relatives are still living on the birdhouse.

(Not pictured; the blind white springtails that live in the wettest part of my garden. They love half-frozen muck; I don't. Not enough to dig about in it looking for them, when I have an excuse to sit at my desk in the warmth and look at their more accessible cousins.)

I was watching Hoppy the spider snacking on a carpet beetle larva, when a fat springtail walked up the glass in front of me. What a good chance to examine his spring mechanism! I grabbed the camera and clicked away, through the steamy glass.

I see the spring, but what are those round things? (See comments.)

And that started me on a quest to make some sense out of springtail anatomy. And the more I read, the more fascinating it turned out to be. I'll explain tomorrow.

Updated, with corrections supplied by Frans Janssens in comments.