What do spiders curl up into a ball when they die, and how their motion inspires modern robotics.
If you have spotted a dead spider while cleaning your house or won a fierce battle with one, you'd probably have noticed that they curl up into a ball with their legs pressed up towards its body. But why is that?
As it turns out, spider legs don't use muscles to extend, rather, they make use of their bodies natural fluids, much like hydraulics.
Spider legs are actually tiny little tubes that can be filled with hemolymph liquid in a fraction of a second. At the base of the legs, where they connect to the spider's body, are extender and flexor muscles to help the spider perform forward and backward motion. But the legs themselves only have flexor muscles, which prevent the spider from ever extending its legs with muscles. When the legs, or "tubes", are filled with hemolymph, they extend.
However, postmortem, there is no hemolymph to extend the legs anymore, therefor the flexor muscles experience rigor mortis.
Robotic engineers are designing components that are inspired by the awesome design of spider legs and how the hemolymph system works, to further improve robotic engineering and technologies.
Take a look at the video below by YouTube channel, SciShow, on Why Do Spiders Curl Up When They Die?