Box jellyfish uses four eyes to look up out of the water

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Recent research has concluded that box jellyfish of the species Tripedalia cystophora have a remarkable system of navigating through the mangrove swamps in which they inhabit – they use visual cues laying above the water line.

"It is a surprise that a jellyfish — an animal normally considered to be lacking both brain and advanced behaviour — is able to perform visually guided navigation, which is not a trivial behavioural task," said Anders Garm of the University of Copenhagen. "This shows that the behavioural abilities of simple animals, like jellyfish, may be underestimated."

Despite being considered simple animals, it has been known to science for over 100 years that box jellyfish have an amazing 24 eyes of four different types – some of which are similar in structure to those of vertebrates and cephalopods – and that those eyes are used for avoiding obstacles and controlling swimming manoeuvres. 

The new research being reported in the April 28 issue of Current Biology, a Cell Press publication, reveals that four of the eyes are always peering up out of the water, no matter which way the jellyfish is oriented. This proves invaluable to the jellyfish which live between the roots of mangrove swamps in the Caribbean, staying close to the surface in order to consume copepods that become abundant in the light shafts penetrating from the mangrove canopy.

By examining the function of the "upper lens eyes" researchers ascertained that the four eyes cover precisely the field of vision needed to see into the terrestrial world, and can detect the mangrove canopy from a distance of at least 8m.

"We have shown that the box jellyfish can use vision to navigate in their habitat, and we now want to understand how their simple nervous system supports such advanced behaviours," Garm said. They also want to know if other box jellyfish species do the same thing in the places where they live.

For further information please read the paper: Garm et al., Box Jellyfish Use Terrestrial Visual Cues for Navigation, Current Biology (2011), doi:10.1016/j.cub.2011.03.054