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Sperm on a stick for springtails

AIR TIME  Springtails (Orchesella cincta shown) use a springlike appendage to fling their tiny bodies, just a few millimeters long, into the air.

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Given the two options, “some females just sit and wait — and suddenly you see a female running to a sperm droplet and picking it up,” Zizzari says. Others make the rounds of droplets on offer, gently touching them with their antennae. “Then she’s not convinced, and she goes for another round.”

As Zizzari peered through a microscope watching the deliberations, only 24 of 40 females made up their minds within 15 minutes. Those that reached a decision preferred, 3-to-1, to touch their reproductive tract openings to a droplet from a male vexed with a nearby rival, she and her colleagues reported December 4 in Biology Letters. Even in a species that evolved anonymous sperm-banking, it seems, competition inspires special effort. 
