They may not be as lethal as their
coastal cousins but the sting of an oceanic box jellyfish is still hard
to ignore: "The pain goes right through your lymph glands and lasts for
hours," says marine biologist, Andy Dunstan, drawing on first hand
experience.
But the chance to learn more about this little known species lured
Dunstan and others from the crew of Undersea Explorer - a combined
adventure dive and scientific research vessel based in Port Douglas -
into a sunset dive with the animals early last month.
"We discovered a spawning aggregation off Osprey Reef, on the outer edge
of the Great Barrier Reef," explains Dunstan. "The jellyfish released
clouds of sperm and then died soon afterwards.
The team sent specimens to the School of Tropical Biology at James Cook
University where senior lecturer, Dr Jamie Seymour, has tentatively
identified the species as "Caribdea".
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"These jellyfish gather to
spawn about eight to ten days after every full moon. The males spawn
first with the females spawning about half an hour later.
"We have recorded sightings, in waters off Hawaii and the Florida coast,
of these animals gathering in single spawning aggregations containing
hundreds of thousands of individuals."
But while only hundreds were seen spawning together off Osprey Reef,
Seymour reports that other aggregations observed off Cairns and
Townsville have numbered in the thousands.
Dunstan describes their jellyfish discovery as being "really cool" -
despite noting that Undersea might have to cut back on naked dives at
the site after a full moon.
"The regular timing of these aggregations will give our researchers
reliable access to the animals," he said, "and could ultimately help us
develop diver safety guidelines with world-wide application."
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