Why do the legs of a dead spider curl up under its body? simple answer .

Spiders do not have muscles for extending the legs at these joints. Spiders, like most creatures, desiccate upon death, losing their waters, explaining why spider legs curl up upon death.

voluntary muscles are controlled by the cerebellum.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.