Image from Monty Graham/Dauphin Island Sea Lab
If you have any interest whatsoever in jellyfish—and, really, who doesn't?—then you should head on over to the National Science Foundation (NSF) website and read their special report on the environmental causes and ramifications of large jellyfish swarms. The interactive site is chock-full of videos, pictures (of course), interesting trivia (for example: a single jellyfish may release up to 45,000 eggs in a day) and several excellent primers on the species' ecology and swarm behavior.
Image from NOAA
It's no secret that jellyfish have slowly, but steadily, begun taking over the oceans in recent years. Thanks to climate change, overfishing, habitat deterioration and other anthropogenic impacts, jellyfish have flourished, both in size and in sheer numbers, often forming swarms of hundreds of millions of organisms.
The Japanese had a harrowing experience in the summer of 2005 when almost 500 million jellyfish—each weighing around 450 pounds—took up residence in the Sea of Japan on a daily basis. On a global scale, the massive swarms have cost the fishing and tourism industries hundreds of millions, perhaps even billions, of dollars in damage since 1980.
As Kimberley wrote about a few months ago, many biologists believe the growing presence of these gelatinous, seemingly innocuous, creatures signals that something is deeply wrong with the world's marine ecosystems. If the pace of their invasion is any indication, it may already be too late to save some of the most vulnerable ones.
Though jellyfish populations typically rise and fall over a 16 to 18-year period, their natural life and reproductive cycles seem to have accelerated under conditions of global warming and anthropogenic impact; indeed, 2008 marked the eight consecutive year that their numbers continued their meteoric rise.
Here are a few more interesting tidbits you'll find on the NSF's website:
1 microsecond is the time it takes a jellyfish stinger to hit its target. The discharge of the jellyfish's stinger is among the fastest movements in nature.
1/3 of the total weight of all life in Monterey Bay is from gelatinous animals.
20-40 people are killed annually from box jellyfish stings in the Philippines alone.
Some of the areas that have witnessed the largest increases in numbers—and the most spectacular swarms—include Hawaii, the Gulf of Mexico, the Bering Sea, the Mediterranean Sea, Australia, the Black Sea and the North Sea. You can see the full breakdown of swarm locations in recent years here.