Box jellyfish

Box jellyfish, also known as Cubozoa, are known for the extremely potent venom produced by some species. They can be found in tropical waters of the Indian Ocean and Pacific Ocean. They have long tentacles and each tentacle has over 5,000 stinger cells. Stings from these and a few other species in the class are extremely painful and sometimes fatal to humans. More importantly, as their bodies are almost transparent, they can attack swimmers without being noticed. Jellyfish also have natural enemies such as sea turtles. Sea turtles have natural immune for the potent venom of Cubozoa. Furthermore, they like eating them. So if you want to surf in the sea where Box jellyfish roam, you'd better bring some sea turtles with you.