Why do Portuguese man-of-war jellyfish have more toxic stings at different times of the year?

We've never heard before that the actual amount of stings each jellyfish has would actually vary, but we certainly know there is annual variation in the amount of people who get stung. This is due to the annual variation in the number of jellyfish in the sea; they change over seasons and are often linked to blooms of plankton, their main food source. Recently there was a boom in the number of jellyfish around the UK, and this caused a big problem for fish farms around the coast.Another interesting fact - Portuguese man-of-war are actually not jellyfish, they are a form of colonial hydroid, lots of little tiny animals stuck together!