The sea wasp, also known as the Australian box jellyfish, is highly venomous and lives in waters around the coast of South East Asia and northern Australia.
The sea wasp is the largest box jellyfish known, and the main body can reach approximately 25 centimeters / 10 inches. Fifteen tentacles trail below the body, and these extend to about three meters / 10 feet when the animal is hunting its regular diet of shrimp and small fish. When swimming, the tentacles contract up into the body to become about 150 millimeters / 6 inches long.
Unfortunately for swimmers, this jellyfish is almost entirely transparent and very difficult to see. Stinging cells on the tentacles are activated by pressure and release an extremely potent venom that instantly causes excruciating pain, leading to unconsciousness and death if untreated.