Meet our guest, glowing a phosphorescent shade of green: a new jellyfish which has arrived from Japan and was observed for the first time in the Mediterranean Sea during a routine survey conducted by Dr. Gur Mizrahi, a researcher from the laboratory of Dr. Dan Tchernov in the Leon H. Charney School of Marine Sciences: the Aequorea macrodactyla (Cnidaria Hydrozoa), a species of medusa spotted repeatedly in the Sea of Japan. The good news: This medusa is not dangerous to humans. The bad news: its arrival heralds that much more dangerous visitors can get here as well. “This is a particularly unique jellyfish, as it contains a fluorescent green-colored protein the role of which, despite many theories, is still not clear to science. Despite its small body – just a few centimeters in length – it devours plankton and small crustaceans; but we can stay calm – as it’s not dangerous to humans,” said Dr. Mizrahi.