through life with no bones, brains or heart, jellyfish lead surprising complex
lives. They are marvelously adapted to a drifting, predatory life in the
ocean. Suspended in the water, the animals gently pulse.
Jellies: The Jewels of the Sea.
Jelly Photos by Dean Solomon
Jellyfish are more than 95% water and have no heart, bones, or brain, and no real eyes. A network of nerve cells helps them move and react to food or danger. Simple sensors around the bell rim let jellyfish know whether they are heading up or down, into the light or away from it..
Jellies have been on the earth for over 650 million years. They were here before dinosaurs and sharks.
Jellies inhabit all oceans of the world. Some jellyfish even live in freshwater lakes.
The largest jellyfish has a bell that can reach 8 feet across and tentacles that extend over half the length of a football field.
Using jet propulsion, jellies can swim up and down in search of their zooplankton food. One Mediterranean jellyfish an inch and a half long pulses 3600 feet a day, a distance equivalent to a 33 mile swim by a six-foot human.
The upside-down jellyfish contains microscopic algae within its tissues. These algae release nutrients which the jellyfish absorbs. If the algae die, the jellyfish will begin to consume its own tissues and may even die.
Jellies are considered a delicacy by many people. After they have been dried and de-salted, they are (according to some) not only delicious, but low in fat, calories, and salt and rich in nutrients. Others claim they taste like rubber bands.
Jellyfish are extremely fragile animals and require a special tank when they are kept in aquariums. Because they tend to get stuck and tear easily, most of the tanks are cylindrical, with no corners.
The umbrella-like form of an adult jelly is called a medusa, so named because of its resemblance to the Gorgon Medusa of Greek mythology with hair of writhing snakes.
Australia's box jelly is the most dangerous jellyfish. Its toxin is more potent than cobra venom and can kill a person in minutes.
called the saucer jelly, this alien-looking creature is named for its
translucent moonlike circular bell. Instead of long, trailing tentacles, these
jellies have a short, fine fringe that helps funnel food—often trapped by
mucus on the bell—into the mouth and the four clearly visible stomach pouches.
This jelly is found worldwide in temperate and tropical waters, where it feeds
in quiet bays and harbors. Although the moon jelly does have a sting, it poses
little threat to humans.
jelly is commonly seen in Monterey Bay during spring and summer, sometimes in
large groups. A cross jelly’s bell grows to about four inches in diameter and
is rimmed with hundreds of fine white tentacles. Four white canals visible under
the transparent bell form an obvious “X” pattern after which the cross jelly
Graceful and nearly
transparent, these jellies have long, delicate tentacles. When disturbed, they
give off a green-blue glow because of more than 100 tiny, light-producing organs
surrounding its outer bell. They can expand their mouths when feeding to swallow
jellies half their size. They’re harvested for their luminescent aequorin,
used in neurological and biological experiments to detect calcium.
Like large bird eggs cracked
and poured onto the water, their three-foot, translucent bells are yolk-yellow
at the center, with hundreds of tentacles clustered around the margin. The
egg-yolk jelly is one of the larger species of jellies commonly found in the
waters of Monterey Bay. With only a mild sting, this massive jelly usually
drifts motionless or moves with gentle pulsing. Acting like an underwater spider
web, it captures other jellies (its favorite food) that swim into its mass of
The Stinging Truth
If you were to think of a major marine predator, probably one of the last creatures to come to mind would be the jellyfish. Although jellyfish look harmless, they are in fact very efficient predators. They are able to stun or kill their prey with stinging cells called cnidocytes. Each of these cnidocytes contains a tiny harpoon called a nematocyst that when triggered by touch or chemicals not only shoots into the prey, but causes the other cells in the area to activate as well. A toxin is also released which stuns or kills the food. The potency of the toxins varies greatly among the different kinds of jellyfish. That is why some jellyfish, like the sea nettle, are only annoying and some, like the box jellyfish, are extremely dangerous if you come into contact with them.
If you are stung, apply vinegar or alcohol immediately to keep the nematocysts from being fired. Next, apply a paste of water and meat tenderizer to the skin. The meat tenderizer will break down the proteins that make up the jellyfish toxin and provide some relief from the pain.
of us have in our veins the exact same percentage of salt in our blood that
exists in the ocean, and, therefore, we have salt in our blood, in our sweat, in
our tears. We are tied to the ocean. And when we go back to the sea...we are
going back from whence we came."
John Fitzgerald Kennedy
are listening to "On your Shore" by Enya
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