Some say that cockroaches, those survivalists par excellence, could inherit the earth. If they do, it’s likely they will be joined by jellyfish populating the oceans or whatever might remain of them. As scientist†Lisa-ann Gershwin details in her book, “Stung! On Jellyfish Blooms and the Future of the Ocean,” jellyfish in vast (really vast) numbers are now showing up all over the world, from the Black Sea to the coasts of Britain, Israel and Brazil.
Jellyfish blooms are a lot more than a nuisance to beachgoers not inclined to swim in waves teeming with gelatinous blobs and tentacles that can sting and poison. What’s going on now, as Tim Flannery writes in reviewing Gershwin’s book in the New York Review of Books,†is nothing less than the jellification (a term used even by scientists) of the ocean with far-reaching consequences and in no small part due to human activity.
Fossils of this gelatinous marine animal are the oldest ever found. The notable upsurge in their numbers is a very recent development and downright alarming for several reasons.
1. For all that they lack†backbones, a heart, blood, a brain or gills and are about 95 water, jellyfish can kill. The†box jellyfish,†Chironex fleckeri, has a bell (the jellyfish’s head) that’s about a foot across, attached to 550 feet of tentacles. 76 people have died from contact since with the box jellyfish since 1884. As Flannery writes, “if just six yards of tentacle contact your skin, you have, on average, four minutes to live ó though you might die in just two.”
2. Jellyfish are invertebrates but some, such as box jellyfish, can hunt medium-sized fish and crustaceans. The ox jellyfish does have some unique features that set it apart from other jellyfish: it has eyes with†retinas, corneas, and lenses and a brain that can learn, remember and direct complex behaviors (like swimming 21 feet per minute.)
3. Get enough jellyfish together and they can bring down a ship. That’s just what happened in November of 2009, when a net of gigantic jelly fish (the largest was 450 pounds) capsized a Japanese trawler and knocked its crew of three overboard. Millions of jellyfish also caused a†major coal-fired power plant in the Philippines to shut down in December of 1999. They’ve also been clogging up the cooling systems of nuclear power plants in Japan and India since the 1960s.
4. Jellyfish are intrepid travelers. Stowed away in the ballast water of ships, jellyfish have made the journey from the U.S. east coast to the Black Sea and been responsible for the vanishing of anchovies and sturgeon in†Bulgaria, Romania and Georgia. Jellyfish eat the eggs and young of anchovies as well as the same food of adult anchovies, who then starve to death.
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