Biologist studying little-understood black jellyfish

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Posted by on August 26, 2005 at 23:19:13:

DANA POINT, Calif. - (KRT) - They float dreamily in the current, pulsating in brainless bliss as their kind has for hundreds of millions of years.

But these jellyfish are in a tank, not the open ocean. The tank is at the Ocean Institute in Dana Point, Calif., and outside the glass, children attending summer science camp shriek in delight at the marine oddities in an array of other tanks around the room - a spiny, 10-pound lobster named Boris; chameleon-like flatfish that change colors to match the gravel in their tank; scorpion fish armed with venomous spines.

The room is the domain of marine biologist Julianne Steers, who, between answering children's questions and tending the pumps and filters that circulate water for the institute's exhibits, has begun to ask fascinating questions.

Steers has captured a number of black jellies, the strange, warm-water jelly fish that washed up for weeks on Orange County shores.

Little is known about these extra-large jellyfish, with their striking, blood red color. They've shown up in large numbers off Orange County just three times in the past 16 years, and only five times since 1926.

The black jellies recently drifted farther north. But Steers plans to breed the ones she caught to learn more about their life cycles and perhaps find out why they sometimes appear so far north of their usual range.

"We can look and see if there's a connection to the red tide," she said. "We can raise the temperature to see if their chemical makeup changes. There is so little known about black jellies, the possibilities are endless."

The floaters, in a tank complete with a gentle current that pushes them around in a slow circle, are juvenile moon jellies. Steers has grown them for years, becoming intimately acquainted with their bizarre life cycle that includes several stages, among them a stationary form with a stalk, called a polyp, that looks like a plant.

Steers hopes the black jellies will grow in a similar manner. One team of scientists produced some larvae in 1999, but Steers could be among the first to raise them to adult form.

The species has been known to science for only a short time. Specimens were first collected and named in 1997.

Now Steers is working to grow the jellies with scientists from the Birch Aquarium at the Scripps Institution of Oceanography, the Cabrillo Marine Aquarium in San Pedro, Calif., and the Long Beach Aquarium of the Pacific.

Scientists know they usually inhabit warmer waters to the south, where they grow to enormous size - 3 feet in diameter with tentacles 15 feet to 20 feet long - and develop their dark crimson color.

Those that washed up in Orange County, while impressive, had probably become smaller during their journey north.

"These animals are definitely at the end of their life," Mike Schaadt, exhibits director at the Cabrillo Aquarium, said. "They're not going to grow into monsters again. They're going to decompose."

Although they are classed as animals, jellyfish - more properly, sea jellies, since they aren't fish at all - are such ancient life-forms they seem truly exotic. They belong to a group called cnidarians, with fossils dating back 540 million to 650 million years.

When it comes to mating and reproduction, the ways of land mammals are simple by comparison.

Jellyfish go through five distinct stages to reproduce.

"It's kind of convoluted," Steers said. "It's not, `Let's just mate and be done with it.'"

Even odder, perhaps, is how jelly fish are organized.

They have what some scientists call a "neural net" that coordinates pulsations, and some evidence indicates they might react to pain. But the net does not qualify as a brain.

The tentacles that hang below are usually armed with stinging cells and, once prey is immobilized, help move it toward the oral opening for digestion.

Yet these tentacles perform their simple operations on their own, without a real brain supervising their movements.

Steers hopes the fact that the jellies that made it to Orange County are near the end of their lives will work to her advantage. At this stage, they tend to release their reproductive material, which would likely make breeding them easier.

Practical uses could emerge from such studies - for example, learning the jellyfish's trick of regenerating damaged tissues, potentially of great use to medicine.

But mostly, Steers wants to open new doors to science.

"I'm more along the lines of, `Can I learn something new about these animals?'" she said.



Jellyfish such as black jellies go through five distinct stages in order to reproduce:

  • Gametes released by males and females mingle in the water, resulting in sexual fertilization.
  • A larva, or planula, develops.
  • his forms a polyp, followed by a budding polyp, which looks a bit like a plant.
  • The polyps form ephyrae, or freshly budded-off disks that will grow into a jellyfish. The ephyrae are identical.
  • The large, bell-like adult form is called a medusa.

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