Jellyfish: millions of years of stinging success
July 29, 1996
Web posted at: 9:20 p.m. EDT
From Correspondent Ann Kellan
BALTIMORE, Maryland (CNN) -- If you enjoy a dip in the ocean
this time of year, beware: it's jellyfish season.
But even though some species' stings can be deadly to humans,
they are an important source of food for sea life, and quite
spectacle behind glass. The National Aquarium in Baltimore,
Maryland, is one place to see them in a friendlier setting.
"Jellyfish have been around for millions of years. They're
very well adapted to surviving in the oceans," said Mark
Donovan with the National Aquarium in Baltimore. "And, what
makes them so neat ... they're kind of something that the
public doesn't really understand."
(519K QuickTime movie of jellyfish)
There are 2,000 species of jellyfish and many have unusual
names, like the upside down jellies, the moon jellyfish, the
tiny umbrellas, and the West coast and East coast nettles.
Seven different jellyfish species grace the aquarium's tanks,
from the tiny elegant jellyfish, as they're called, to the
lion's mane, which packs the most powerful sting of the
"They sting in order to capture their food," Donovan said.
"It's just a coincidence that man kind of goes into their
area in the oceans and gets stung."
The sting comes from tiny weapons on the jellyfish's
"They fire all these little nematocysts, which are millions
and millions of little harpoons, to kind of grab the food and
pull it into them," Donovan added.
The jellyfish have what are called oral arms that move the
food to their mouths. The jellies in the exhibit get to
feast on specially-prepared brine shrimp.
Looks can be deceiving
The aquarium's exhibit is not quite as simple as it seems,
but then neither are the jellyfish. They live in special
tanks, that are designed to simulate the moving ocean, which
keeps the jellies afloat. Without moving water, jellyfish
will sink to the bottom and die.
Another challenge to keeping them alive is keeping bubbles
out of the tanks. Bubbles can literally eat their stomachs
out, or collect on the jellyfish making them so buoyant they
Moving them from tank-to-tank is also tricky, because these
primitive creatures are 95 percent water.
Aquarium visitors also learn some interesting facts about
nature. For example, jellyfish are not even fish, they are
spineless invertebrates. And Man o' Wars (such as the
Portuguese) are not quite jellyfish. However, they are a
colony of stinging animals that are members of the same
family as jellyfish.
The jellyfish may be headless, heartless creatures, but
they've earned the respect of those who visit the aquarium's
exhibit. After all, they've managed to survive 650 million
years on this planet.
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