Whenever water fleas (Daphnia pulex) sense a predator nearby, they grow their sharp, minute ridges below their tiny heads known as neckteeth. The predators of these water fleas are the glassworms or phantom midge larvae, commonly found in lakes all over the world. Through the incredible efforts of scientists, the attack of the phantom midge larvae on water fleas was recorded and is now known as one of the fastest attacks in the entire animal kingdom.
In the documented attacks, the glassworm ambushed the water fleas with its elongated, segmented bristles. The appendages unfurled rapidly then contracted into what seemed like a catching basket. In just about 14 milliseconds, the glassworm’s special bristles reached the water fleas. The instant this predator has the Daphnia in the basket, it merely requires 43 milliseconds more to retract and then it starts to swallow its prey.
The defenses of the water fleas is still a mystery. Their neckteeth seems to interfere with how the glassworm’s catching basket works. Because of this action, 80% of the water fleas that grow their neck teeth actually evade capture.