Nematocysts can continue to fi

Nematocysts can continue to fire even after a jellyfish has died, so it's important to remove lingering tentacles stuck to the skin. Rinsing with vinegar will usually render undischarged nematocysts inactive. Seawater can also help remove residual nematocysts. But don't use fresh water because any change in salt balance alters the osmotic pressure outside of the cnidocyte and will trigger the nematocyst to fire.