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| At the Ocean Institute, Julianne Steers grows phytoplankton to feed brine shrimp, which then feed jellies. Elisabeth Deffner |
When is a fish not a fish? When it's a jelly!
Black jellyfish usually live deep in the sea. But every five to eight years, they rise to the surface where they can be seen by humans.
By Elisabeth Deffnerfrom the September 18, 2007 edition
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Julianne Steers was aboard a 22-foot Boston Whaler in the Pacific Ocean when she saw them in the sea: rare black jellyfish.
Every five to eight years, black jellyfish – which normally live at ocean depths of 2,000 to 3,000 feet – rise to the surface. In the summer of 2005, a large number of black jellies surfaced off the coast of southern California, where Ms. Steers is a marine biologist at the Ocean Institute in Dana Point. They hadn't been seen in the area since 1999.
"Black jellies are a remarkable species, often growing up to a meter [about three feet] in bell size," says Ms. Steers. The "bell" is what some people call the body of the jellyfish.
When Ms. Steers spotted the black jellies, she collected a few and took them back to the lab. She hoped they would reproduce so that she and other researchers could study them. She was disappointed when they didn't – but she plans to try again the next time black jellies surface.
Until then, she has plenty of work to do with the aquarium's hundreds of moon jellyfish. These are one of the most common types of jellyfish.
Ms. Steers began investigating the interesting characteristics of the elegant white creatures when she started working at the Ocean Discovery Center at the University of California, Los Angeles. Later, when she worked at the Aquarium of the Pacific in Long Beach, Calif., a co-worker told her that some of the facility's moon jellyfish had small wounds caused when the jellies bumped up against the walls of their aquarium.
One day she removed a wounded jellyfish from the tank and put it in a small bowl by itself. Using a tiny pair of scissors, she removed the dead tissue. The jellyfish then regenerated its tissue. In other words, it grew new tissue to replace what she had removed.
Ms. Steers knew that jellies could make new tissue – but she was excited to learn that they could regenerate so much at one time.
Anatomy of a jelly
Just what are jellyfish, anyway? Well, they are not fish. Fish have skeletons, and jellies do not. Scientists also say that they don't have brains or hearts – but this hasn't affected the animals' survival. Jellies have inhabited the earth's oceans for more than 500 million years. There are more than 200 kinds of jellies, and most of them have a body shaped like a bell. From the bell's edges, tentacles hang down that stun or kill prey. "Oral arms," which dangle from the center of the bell, bring food to a jelly's mouth.
Some kinds of jellies are so small that the bell measures less than an inch across. And one of the biggest types of jellyfish, the North Atlantic lion's mane, can have a bell that grows up to eight feet in diameter.
Jelly tentacles grow to different lengths, too. The irukandji – a tiny jellyfish found off the coast of Australia – has tentacles that usually grow between one and 10 inches long. But the tentacles of the North Atlantic lion's mane can grow to more than 120 feet long.
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