ScienceDaily (Nov. 26, 2009) — With thousands of stinging cells that can emit deadly venom from tentacles that can reach ten feet in length, the 50 or so species of box jellyfish have long been of interest to scientists and to the public. Yet little has been known about the evolution of this early branch in the animal tree of life.

Courtship behavior of the box jellyfish Copula sivickisi. The male (top) and female (bottom) engage in a complex mating ritual unique among cnidarians (jellyfishes, hydroids, anemones, corals and their kin). (Credit: Image courtesy of Alvaro E. Migotto)

In a paper published November 18 in the Proceedings of the Royal Society, NOAA researchers Allen Collins, Bastian Bentlage and Cheryl Lewis Ames of the Northeast Fisheries Science Center's National Systematics Laboratory and colleagues from the University of Kansas, Pacific Biosciences Research Center in Hawaii and the University of Queensland in Australia have unraveled the evolutionary relationships among the various species of box jellyfish, thereby providing insight into the evolution of their toxicity.

"By determining the relationships among the different box jellyfish, some of which are capable of killing a healthy human, this study can help in the future development of antivenoms and treatments for their stings," said Collins, a specialist in Cnidaria (pronounced nidaria), the phylum of animals that includes box jellyfish. "Researchers will now be able to make more informed choices about organisms for future venom studies, and make predictions on which species are likely to be of public health concern in addition to the known culprits."

Beyond their toxicity, box jellyfish have other interesting characteristics.Some species have as many as 24 eyes, capable of sensing light and forming an image of their surroundings. Why they have complex eyes, how well they see, and what role vision plays in their mating and feeding behavior remain unknown.

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