WATCH: Irukandji box jellyfish lures then eats a fish
THIS is how the Irukandji box jellyfish feeds.
It attracts tiny larval fish by twitching its tentacles, using them as a lure to then sting and reel in its prey.
Not bad for an animal that doesn't have a defined brain.
James Cook University has published the results of this first feeding study of the Irukandji, in the PLOS One online journal.
The study of the "Carukia barnesi" was done at JCU's Australian Institute of Tropical Health and Medicine in Cairns.
Lead author Robert Courtney said the creatures are 96% water, have no defined brain or nervous system, yet they're able to use their tentacles as a fishing line and lure.
"They're not opportunistically grazing - they're deliberately fishing," he said.
"They're targeting and catching fish that are at times as big as they are, and are far more complex animals.
"This is a really neat animal that is displaying a surprisingly complex prey capture strategy."
During the night they rest, but during the day, the stretch their tentatcles as long as 1.2 metres with the "nematocyst clusters" (stingers) evenly spaced along like a fishing line.
"The nematocyst clusters look like a series of bright pearls, which the jellyfish twitches to attract the attion of its prey, like a series of fishing lures," Mr Courtney said.
"It's a very deliberate and selective form of prey capture."
Once the fish touches the stinger, it is paralysed by the Irukandji's venom.