Box jellyfish live by the coasts of Australia and in the Indo-Pacific Ocean. They have up to 15 tentacles, which can reach 10 feet in length. Although they do not have a central nervous system, box jellyfish have advanced vision.
Box jellyfish, also called "sea wasps," hold venom that is among the most dangerous in the world. This venom contains toxins that attack the skin cells, heart and nervous system of humans. If stung, humans tend to go into shock or heart failure, and may drown before they reach shore. These jellyfish are light blue and somewhat transparent in color. Box jellyfish get their name from their box-like bells.