There have been recent news stories about giant jellyfish washing ashore from Maine to the south coast of Massachusetts. These stories have claimed that some of these lion’s mane jellyfish have been the largest on record and even might be the largest animals in the ocean.
The truth of these accounts is rather suspect. For one thing, it is rather difficult to measure the size of a jellyfish when it is out of the water. Gravity compresses and spreads out the bell portion of the animal, and that makes up the bulk of its mass. For example, a jellyfish bell that measures four feet across on the beach would appear to be much smaller if the animal was floating in the water.
Some claims that lion’s mane jellyfish are larger than blue whales date back a full century and are very much disputable. The claimed size certainly included the animal’s long tentacles, and such things hardly compare with a blue whale.
In any event, the current spate of jellyfish sightings is not necessarily that unusual. Many factors influence jellyfish populations, including water temperature and food supply. It is possible that warming water temperatures may be influencing the jellyfish population this year, but there is not enough data to know for sure.
People do need to be cautious around lion’s mane jellyfish. They do sting and while their stings are not as bad as those of a number of other species, they can be a problem for people who have allergic reactions. Furthermore, the stinging cells remain active in a jellyfish that has washed ashore.
Sightings of these animals are continuing, and reports of larger specimens continue as well, even if they don’t compare with blue whales.
Photo, posted September 13, 2015, courtesy Derek Keats via Flickr.