What happens chemically when the opossum plays dead?

When an opossum plays dead, a response known as thanatosis occurs, triggered by extreme stress or fear. Chemically, the opossum's body releases high levels of stress hormones like cortisol, which can induce a state of paralysis and a drop in heart rate. This mimics death, causing the animal to become limp and unresponsive, while also producing a foul-smelling secretion from its glands to deter predators. This strategy effectively makes the opossum less appealing to threats until the danger passes.