They’re Taking Over! (Jellyfish)

[n2doc]

Tim Flannery

A moon jellyfish and cross jellyfish floating in a remote channel near Victoria Island, British Columbia; photograph by David Hall from Beneath Cold Seas: The Underwater Wilderness of the Pacific Northwest, which collects his images of marine life in that region. It is published by University of Washington Press.

It’s become fashionable to keep jellyfish in aquariums. Behind glass they can be hypnotically beautiful and immensely relaxing to watch. Unless we are enjoying them in this way, we usually give little thought to the creatures until we are stung by one. Jellyfish stings are often not much more than a painful interlude in a seaside holiday—unless you happen to live in northern Australia. There, you might be stung by the most venomous creature on Earth: the box jellyfish, Chironex fleckeri.

Box jellyfish have bells (the disc-shaped “head”) around a foot across, behind which trail up to 550 feet of tentacles. It’s the tentacles that contain the stinging cells, and if just six yards of tentacle contact your skin, you have, on average, four minutes to live—though you might die in just two. Seventy-six fatalities have been recorded in Australia since 1884, and many more may have gone misdiagnosed or unreported.

In 2000 a somewhat less venomous species of box jellyfish, which lives further south, threatened the Sydney Olympics. It began swarming at the exact location scheduled for the aquatic leg of the triathlon events. The Olympic Committee considered many options, including literally sweeping the course free of the menace, but all were deemed impractical. Then, around a week before the opening ceremony, the jellyfish vanished as mysteriously as they had appeared.

Most jellyfish are little more than gelatinous bags containing digestive organs and gonads, drifting at the whim of the current. But box jellyfish are different. They are active hunters of medium-sized fish and crustaceans, and can move at up to twenty-one feet per minute. They are also the only jellyfish with eyes that are quite sophisticated, containing retinas, corneas, and lenses. And they have brains, which are capable of learning, memory, and guiding complex behaviors.



more
http://www.nybooks.com/articles/archives/2013/sep/26/jellyfish-theyre-taking-over/?pagination=false

[Owl]

1. Saw lots of moon jellies sea-kayaking in Alaska a few years back.

[longship]

2. Scary creatures. R&K nt

[enough]

3. The wave of the future.

snip from the article>

Jellyfish reproduction is astonishing, and no small part of their evolutionary success: “Hermaphroditism. Cloning. External fertilization. Self fertilization. Courtship and copulation. Fission. Fusion. Cannibalism. You name it, jellyfish [are] ‘doing it.’” But perhaps the most unusual thing is that their eggs do not develop immediately into jellyfish. Instead they hatch into polyps, which are small creatures resembling sea anemones. The polyps attach to hard surfaces on the sea floor, and are particularly fond of man-made structures, on which they can form a continuous jelly coating. As they grow, the polyps develop into a stack of small jellyfish growing atop each other that look rather like a stack of coins. When conditions are right, each “coin” or small jellyfish detaches and swims free. In a few days or weeks, a jellyfish bloom is observed.

snip>

[eomer]

4. I for one...

Obligatory post taken care of, you're welcome.

[DetlefK]

5. We need more sea-turtles. They feed on jelly-fish.