Why Do Spiders' Legs Curl Up Like That When They're Dead?
Spiders lack blood and some leg muscles, so what is going on?
Usually, it's the number of legs and that strange scuttling motion that sets off arachnophobes. But with all eight legs motionless when you find an unfortunate deceased spider behind the sofa, we ask the question: why do their legs curl up when they die?
Inside a spider, there isn't blood like a mammal but a fluid called hemolymph – a pressurized liquid that helps the spider's body act a bit like a hydraulic system.
The muscles in a spider's legs help bend the legs inwards, and the hydraulic hemolymph liquid is pushed into them to spread them outwards.
Spider legs don’t have extensor muscles, which means that the flexor muscles can get stronger and stronger. This helps the spiders grip onto their prey species and climb up vertical surfaces.
Author's summary: Spiders' legs curl up when they die due to their unique anatomy.