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By Erik Stokstad
When water fleas detect certain predators that are hiding nearby, they develop tiny, sharp peaks under their heads called necks. These predators – larvae of ghost midges, also called glass worms – are common in lakes around the world. Scientists are now trying to figure out how the work done on the ties captured the first high-speed images of a glassworm attack – and found it to be one of the fastest in the animal world.
To document 48 attacks, scientists each placed three water chips (Daphnia pulex) and a glass worm in an aquarium specially designed for high-speed shooting. Where & # 39; a Daphnia snaking at hand, the glass worm ambushed him with long joined silks that quickly unfolded and contracted (above) into a "catch basket". hairs that move laterally during the attack. Other researchers had doubted that these lip hairs could move because they lacked muscle. But they could be powered by the pressure of internal fluids.
The new videos also allowed the researchers to time the attack: the worm hair reaches the Daphnia in just 14 milliseconds on average, one of the fastest known strikes, they reported last week in PLOS ONE. (For comparison, mantis shrimp attack in just 4 to 8 milliseconds, and record ants and trap spiders take less than 1 millisecond.) Daphnia in his basket, he needs only 43 milliseconds more to retract and start swallowing his prey.
The nature of DaphniaThe defenses remain a mystery. Scientists say that brains probably interfere with the action of the catch basket. Other experiments under more realistic conditions show that about 80% of Daphnia with neckteeth avoid capture, compared to only half that lacked these defenses. For those who do not escape, at least, the end is thankfully fast.
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