Animal · Australia, Papua New Guinea, Indonesia
Box jellyfish
Chironex fleckeri — the name this animal has in the language scientists everywhere share.
The box jellyfish is a pale, almost see-through sea animal with a bell shaped like a cube and long trailing tentacles that carry a powerful sting. It hunts prawns and small fish in warm coastal water.
Picture credit: Rickard Zerpe (CC BY 2.0) · Peter Southwood (CC BY-SA 3.0) · Wikimedia Commons
Where does the box jellyfish live?
Home: Warm coastal waters of northern Australia and Asia.
In the wild it lives in these countries: Australia, Papua New Guinea, Indonesia, Timor-Leste, Malaysia, Singapore, the Philippines, Vietnam.
The short profile
Fully grown: bell up to 30 cm across, tentacles up to 3 m. It weighs about 2 kilograms. On the menu: meat.
The story behind it
Unlike most jellyfish, a box jellyfish does not simply drift. It pumps its cube-shaped bell and swims at a steady pace, turning and steering between mangrove roots and sandbanks. Around the edge of the bell sit twenty-four eyes in four groups; some are simple light detectors, others have a lens, like our own eyes. The animal has no brain at all, only a ring of nerves that joins everything together. Up to sixty tentacles hang from the four corners, each one covered in stinging cells that fire the moment they touch a prawn or a fish. In northern Australia, beaches are netted in the warm season and swimmers wear thin stinger suits, because a serious sting needs medical help at once.
Find it on the globe
Box jellyfish is there as a tiny animated figure that breathes and looks around. From far away the planet is only a blue ball; detail arrives as you zoom in, and this one appears once you are close enough. Open it on the globe.
It sits at its real coordinates, not near them — the same numbers listed in the facts above. Switch off the layer for this kind of place and it disappears again; the buttons for that are down the right-hand edge.
Questions children ask
Why is it called a box jellyfish?
Because of its shape. Seen from above, the bell is square, and from the side it looks like a small transparent box with a tentacle hanging from each corner.
Can a box jellyfish see without a brain?
It has twenty-four eyes and no brain. Four of those eyes even have a lens, like ours. The signals run through a ring of nerves around the bell, which is enough for the animal to avoid obstacles and swim towards clearer water.
How dangerous is a box jellyfish sting?
Very. It is one of the most painful stings in the sea and a bad one can be life threatening, so it always needs medical help at once. In northern Australia swimmers wear thin stinger suits and many beaches are netted in the warm season.
Where these numbers come from
Every figure on this page was checked against public reference sources before publication. Where sources genuinely disagree, the text says so.
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