The Box Jellyfish (Cubozoa) is one the most venomous jellyfish on the planet. It is found in subtropical and tropical waters. The box jellyfish are invertebrates distinguished by their cube-shaped medusae.
The medusa form of a box jellyfish has a squarish, box-like bell. From each of the four lower corners of this hangs a short stalk which has one or more long, slender, hollow tentacles. The rim of the bell is folded inwards to form a ledge known as a velarium which restricts the bell’s opening and creates a powerful jet when the bell pulsates. As a result, box jellyfish can move quicker than other jellyfish; speeds of up to six meters per minute have been recorded.
Although the box jellyfish has been called “the world’s most venomous creature”, only a few species in the class have been confirmed to kill humans, and some species pose no serious threat at all. For example, the sting of Chiropsella bart (a jellyfish) only results in short amount of itching and mild pain.
Once a tentacle of the box jellyfish makes contact with skin, it pumps nematocysts with venom into the skin, causing the sting and agonizing pain. Rinsing the sting with vinegar is used to deactivate undischarged nematocysts to prevent the release of additional venom. A 2014 study reported that vinegar also increased the amount of venom released from already-discharged nematocysts; however, this study has been criticized on methodological grounds.