The hydraulic secret behind why spiders curl up after death

Science · Published 8 October 2026 Swipe more like this →

In short: Ever noticed a spider's legs tucked tightly against its body after it dies? This movement isn't caused by muscle contraction, but by a fascinating biological mechanism.

While we often assume limbs move via muscle tension, spiders rely on a hydraulic system to extend their legs. Because they lack the muscles required to push their limbs outward, the loss of internal pressure upon death causes the legs to retract and curl inward.

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