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Large number of moon jellyfish encountered around Mission Bay

**Note about the video:** The narration appears not to be working, but it shows some of the jellyfish that have been showing up on San Diego's beaches. Hopefully, the sound quality will be fixed, soon.

Moon jellyfish
Photo by Dan Kitwood/Getty Images

Moon jellyfish have been seen washing up on shore in large numbers, lately, in San Diego. This isn’t anything unusual, it happens just about every year. The numbers are said to be higher than usual with reports reaching over 100 individuals at a time in the Mission Bay area alone. There are also large numbers of them seen offshore. Paddle boarders state that they are often surrounded by jellyfish underneath them.

Moon jellyfish are generally not harmful to human beings. Their sting is said to be mild and pose no threat. If you touch one of these jellies, be sure to keep your hands away from your mucous membranes such as your eyes, nose and mouths. If you’re stung, make sure you wash the sting with salt water and see a lifeguard for treatment. Mostly, the issue with them washing up on the beach is that they’re slippery and can cause you to fall if you step on them.

These jellyfish congregate in large numbers along just about every coastal area in the world. Though they have a temperature preference for waters that are between 48-66 degrees Fahrenheit, they can actually tolerate much higher and lower temperatures. Though most jellies float with the currents, moon jellyfish can propel themselves by expanding and contracting its bell. They mostly eat plankton and other small animals which they trap with their mucous-filled tentacles.

The recent increase in jellyfish sightings may be linked to a change in the weather as well as more rain washing nutrients offshore. The increase in numbers and stranding of these jellyfish can be a boon to sea turtles and shorebirds who feed on these creatures. The annual increase happens just in time for nesting and breeding season.

Several species of jellyfish often “invade” San Diego shores during the warmer months of the year. Some of these species’ stings are worse than others, so all should be approached or handled with the highest of caution. Stings can be extremely painful and some species’ stings can do damage.