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Photo#165505
Springtails #2 - Sminthurides

Springtails #2 - Sminthurides
Santa Clara County, California, USA
January 15, 2008
Size: about 0.5mm
Several springtails. The very largest seem to have a grey-blue body, while the smaller have a stripe, and the smallest lack the dark color completely.

I wonder what the head to head position is that 3 pairs of them are in.

Sminthurides sp.
Family Sminthurididae (note the ...idid...).
In all the members of this family, the males, that are much smaller than the females, have modified antennae, called grasping antennae. The males are able to grasp with their antennae the base of the antennae of a female in head to head position. If you carefully look around in a population of such springtails you will certainly find (larger) females carrying upside down and attached to their antennae a smaller male. Compare this behaviour as that of a male toad that jumps on the back of the larger female and holds on to it to 'mate' later.
In Sminthurides, when the female comes 'in the mood', she will put down the male back on its feet. He will produce one or more spermdrops (spermatophores) that he will deposit in her neighbourhood. Then he will convince the female to uptake the spermdrop by pussing/pulling her in the right direction. There are many species specific variants of this 'mating' behaviour. Sminthurididae do not dance as in Bourletiellidae, in which the males are excellent dancers.

The head to head couples in this pictures are males or juveniles practicing their grasping technique at eachother.

mating behavior
Nice find! The pairs butting heads are probably male/female pairs doing mating rituals of sorts. At least that's what I learned from David Attenborough's "Life in the Undergrowth" videos. You can see Attenborough's springtail video here (click on "Dancing Springtails"). The footage is highly entertaining!

 
Good point, Joyce!
But note the difference in mating behaviour in Sminthurididae and Bourletiellidae (= Attenbourough's video).

In Sminthurides, the male grasps the female with its grasping antennae.
And he will not release her. Given the male is much smaller than the female he will be lifted up be her seemingly without effort. He will then be 'connected' to her for a while. When the female comes 'in the mood for love', she will put down the male back on its feet. He will then deposit one or more spermatophores in her close neighbourhood. Then he will convince the female to uptake the spermdrop by pussing/pulling her in the right direction. There are many species specific variants of this 'mating' behaviour. Sminthurididae do not dance as in Bourletiellidae, in which the males are excellent dancers.

So, the 'head banging' in Sminthurididae is quite different from that in Bourletiellidae. While in Bourletiellidae it is a more true kind of head banging, in Sminthurididae it is head/antennae grasping.

 
fascinating
Thanks for the additional information Frans -- very interesting to know the differences (and similarities) in behavior between the different families.

 
Thanks, Joyce!
I Will take a look at that video. They really seem unusual, just from what I've seen and read so far. I read a comment on Beatriz' springtail submission indicating they become more active in cool weather. What I have seen is that they actually seem to collect on the surfaces of leaves that have iced over preferring them to ones that are only wet. You'd think that the freezing temperatures would slow them down some, but somehow just the opposite!

 
Hi Mac
Many springtails have a kind of antifreeze in their blood that allows them to remain active at freezing temperatures while other arthropods are simply unable to move.
In this way Collembola can take advantadge of the winter period as competition then is quite low.

 
Hello, Frans
I've seen your website on springtails, very impressive. I haven't had a chance to learn much about them, but they are very compelling, due to their strangeness, I guess.

These particular springtails actually seem to gather on icy spots of leaves (on living plants)and around decaying spots.

Coincidentally, I just posted a picture of a much larger possible springtail. It is 2-3mm long, and shaped more like a lobster.

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