Chiropsalmus quadrumanus
Chiropsalmus quadrumanus, commonly known as the four-handed box jellyfish, is a species of box jellyfish found in the western Atlantic Ocean, the Gulf of Mexico and the Pacific Ocean. The sting is venomous and dangerous to humans, especially children.
Dead zone (ecology)
Despite most other life forms being killed by the lack of oxygen, jellyfish can thrive and are sometimes present in dead zones in vast numbers. These jellyfish blooms produce mucus and waste, leading to major changes in food webs in the ocean. The organic carbon is metabolised by bacteria which return it to the atmosphere in the form of carbon dioxide in what has been termed a "jelly carbon shunt".