Box jellyfish

Box jellyfish (class Cubozoa) are cnidarian invertebrates distinguished by their cube-shaped medusae. Some species of box jellyfish produce extremely potent venom: Chironex fleckeri, Carukia barnesi and Malo kingi. Stings from these and a few other species in the class are extremely painful and can be fatal to humans.

Nomenclature

"Box jellyfish" and "sea wasp" are common names for the highly venomous Chironex fleckeri. However, these terms are ambiguous, as "sea wasp" and "marine stinger" are sometimes used to refer to other jellyfish.

Anatomy

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 pedalium or stalk which bears one or more long, slender, hollow tentacles. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates. As a result, box jellyfish can move more rapidly than other jellyfish; in fact, speeds of up to six meters per minute have been recorded.