Workers in Japan haul in swarms of Nomura's jellyfish from the waters off Iwate Prefecture in December 2005.

 

 

A Nomura's jellyfish floats off Japan's Nagasaki Prefecture in August 2005.
Relatively little is known about Nomura's jellyfish, so Shin-ichi Uye, a professor at Hiroshima University, and colleagues across Japan have been studying the giant jellyfish in the lab to learn more about their habits and reproductive strategies.

The scientists are still not sure why thousands of the creatures appear off the Japanese coast in some years but not others.

"It is possible that they have a 'rest stage' or hibernation period in their development over several years, but then their numbers shoot up given certain environmental stimuli," Uye said.

Fact: Despite their name, jellyfish are actually not fish! Jellyfish are made up of over 95% water, and they do not have brains, hearts, gills, bones, or blood. So, if jellyfish are not fish, what are they? Jellyfish belong to an animal group called invertebrates, because they do not have backbones. Fish are vertebrates, because they have backbones.
Via Edhelper