What are jellyfish? Jelly fish are free swimming marine animals. They can be found in all oceans on Earth. They are usually a gelatinous bell shaped body with tentacles trailing from underneath. Many jellyfish will not harm you if they sting but some are extremely painful and some are deadly.

How they sting. Jellyfish sting their prey using nematocysts – which are stinging structures located in specialized cells called cnidocytes. When a human or animal comes in contact with a jellyfish it can trigger pressure to build up inside the nematocyst rapidly up to 2000 pounds per square inch (14,000 kPa) until it bursts. This is a huge amount of pressure, I pump up my soccer balls to 70 psi !!!

“ Each jellyfish tentacle is covered with thousands of cells called cnidoblasts, which house nematocysts containing stinging threads. When a jellyfish encounters another object, pressure inside the nematocyst causes the threads to uncoil. The stinging cells spring out at the victim like tiny darts, firing venom into it. The venom is a neurotoxin designed to paralyse jellyfish prey.” Stephanie Watson from Boston University says in her article “How Jellyfish work”

This video shows how this happens