The deadly box jellyfish Chironex fleckeri is commonly called the sea wasp.
Chironex fleckeri is also known as the Australian box jellyfish. It lives in coastal waters of northern Australia and parts of the Indo-Pacific. The nickname “sea wasp” reflects the extreme pain and danger of its sting, not an appearance resembling a terrestrial wasp.
Its tentacles can extend to about 3 metres and carry millions of cnidocytes, specialized stinging cells that fire microscopic structures when triggered by contact. A severe sting can affect the cardiovascular system rapidly and may be fatal within minutes without urgent treatment.
The name can cause confusion because “box jellyfish” refers to the broader class Cubozoa, while Chironex fleckeri is one particular species. Crystal jelly, moon jelly and lion’s mane jellyfish are different jellyfish and are not alternate names for this species. “Australian box jelly” and “sea wasp” are the key common names readers are likely to encounter.