Jellyfish and You

Everyone has seen them, but do you really know what exactly they are? And which will sting you? Which ones are dangerous? If you’re like most snorkelers or divers, chances are you have seen more than one jelly fish. But don’t despair! Not all jellyfish in Key Largo are ones you have to worry about, and if treated with caution can be a beautiful part of a snorkel or dive. These gelatinous creatures, many with orb-like bell bodies and stinging tentacles, have a sneaky way of ruining a day in the water. The irony is they’re fascinating and oddly beautiful creatures.

Jellyfish are even considered the oldest multi-organ animal! They are free-swimming carnivores drifting in the wind and currents, although some can add an extra bit of slow propulsion by contracting their bell where the tentacles attach. The diet consists of plankton, crustaceans, small fish, and even other jellyfish. So nothing to worry about for you!


Common Jellyfish in Key Largo

Moon Jellyfish:

A variety of jellyfish seasonally make their way though the Keys. The most common one you’ll see will the the good old moon jellyfish. Ranging in shades of pink and purple, this type of jellyfish has a translucent white, saucer-shaped bell with a blue-gray transparent disk at the center. Tentacles hang from the outer fringes of the bell. While they’re not poisonous, you’ll definitely know if you brush up against one because they’ll produce a sharp, uncomfortable stinging sensation. Moon jellyfish are seen here year-round, but more often in late summer/early fall. They tend to float gently


A much less friendly (and thankfully MUCH less common!) of our jelly visitors is the infamous Portuguese Man-o-War. You can easily identify this bad boy by the the deep blue/purple sail-shaped bell floating at the surface. That’s also how they get their alternate name the “bluebottle.” The deep colored tentacles trail behind them for 10-15 ft. This guy can deliver a pretty painful sting! It’s in your best interest to avoid these guys. The up side is that very rarely do we actually see Man-O-Wars when snorkeling/diving, as they only rarely come in. Interestingly, they are not actual jellyfish, either! Rather than being one organism, it’s a collective of individual animals called zooids or polyps. They all have to work together to survive as they won’t individually.

Comb Jellyfish:

 Also a common site on the reefs. But good news: These guys don’t sting! The comb jelly looks different from other jellies, and is not made up of a bell and tentacles. Instead, it is a small (a few inches long) translucent oblong body with little bumps. For this reason, it’s sometimes called a sea walnut. Comb jellies are translucent but refract light, appearing to have rainbow colors running down their bodies.. They can also make their own light (bioluminescence), flashing when disturbed. You’ll often find them floating gently just under the surface of the water, and if you get close enough you can see the colors moving up the sides of their bodies.


What to Do if You Get Stung

You’ve been stung! What do  you do now? Well, it’s actually pretty easy. The best way to deal with a jellyfish sting is deactivate the stinging cells and remove the tentacles/stinging cells. Don’t put fresh water on a sting! This may actually activate any un-stung tentacles left on your skin. You can rinse the area with saltwater and then apply vinegar. That’s right, normal off-the-shelf vinegar (which many boats will have on hand) can help calm the sting and deactivate the stingers. And using a razor or side of a card to scrape the skin can remove any remaining tentacles or stingers.


We have other jellys that come and go through the Keys, but these guys are the “locals” that we do see and notice. So the next time you’re out snorkeling or diving, take a look near the surface for your free-floating friends! You can make an awesome photo with a well placed jellyfish near the surface. And if you’re aware you can observe them without threat of sting.


comb jellyfish
Common comb jellyfish
moon jelly
Moon Jellyfish
man o' war
Portuguese Man-O-War
Jellyfish – What exactly ARE they?