We just learned about the Tentacles of a jellyfish.
Another part of a jellyfish is the Nematocyst.
This is the part of the jellyfish that stings its prey, or even stings a person.
They are almost like traps on the jellyfish's tentacles that just wait until they get touched a tiny bit, and then they shoot out and then squirt toxins into their prey to stun them or kill them.
(from: wikipedia - cnidocyte)
Kid Facts - Blast from the past: Chromatophore