Yes, jellyfish can still sting even when they are dead. This is because a jellyfish's body is about 95% water, and as long as the tentacles remain hydrated or damp, the nematocysts (stinging cells) can still fire their venomous harpoons. These nematocysts contain toxins that can be triggered by pressure or contact, causing stings even if the jellyfish is no longer alive. Therefore, touching a dead jellyfish or its tentacles can still result in a painful sting.

It is advised to avoid touching jellyfish washed up on the beach, whether they appear alive or dead, because their stinging cells can remain active for some time after death.