GWEN IFILL: It’s that time of year when many folks are heading to the beach. But along parts of the southeast coast, vacationers may run into some unwanted visitors, as the National Weather Service has issued hazard warnings caused by jellyfish found in Myrtle Beach, South Carolina.

That’s temporary, but what’s not are the persistent numbers of the slimy creatures populating the waters of the ocean.

Science correspondent Miles O’Brien reports, just in time for the summer, for our weekly series on the Leading Edge of science and technology.

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