Jellyfish are found in every
ocean of the world. They are even found in some freshwater lakes and
ponds.[6]
Jellyfish range from the size of
a thimble or the eraser tip of pencil to approximately eight feet in
diameter with tentacles that reach 200 feet. That is as long as two blue
whales.[1]
Each jellyfish tentacle is armed
with thousands of cells called cnidoblasts. Inside the cnidoblasts are
nematocysts, each of which contains a coiled stinging thread. When a
fish or other object becomes tangled in the tentacles, the pressure
inside the nematocysts causes the venomous threads to uncoil like a
spring-loaded harpoon