Today is World Oceans Day, so follow the lead of a creature that goes wherever the water takes it. Want to spot a lion"s mane jellyfish? Look in cold northern seas. Its bell is split into eight lobes, and beneath it hang long tentacles and oral arms. As it drifts with the current, stinging cells snare plankton and small fish. For humans, the sting can be painful. Reactions vary, and even a washed-up tentacle can still hurt. The rule is simple: admire it, then leave it alone. Some lion"s manes in Arctic waters have bells more than 6 feet across, but most sightings are smaller animals near shore after storms or strong currents.