Completely fascinating on one hand, and absolutely terrifying on the other – The Jellyfish!
These gelatinous blobs mostly drift through our oceans, often at the whim of the current and the wind, with no other goal other than to feed, reproduce.. and scare unsuspecting swimmers!
With around 200,000 jellyfish stings recorded in Florida annually, you may like to know what kinds of jellyfish Florida has lurking in it’s waters, and what (if any) danger they pose.
And so, here is our list of some of the most common (or just simply interesting!) jellyfish species in Florida.
Moon Jellyfish are super common in Florida, (maybe the most common). They’re also really common throughout the worlds oceans too.
They have limited motion so they mainly drift with the current whilst feeding by attracting plankton with it’s tentacles, which it then brings into its body for digestion
Because of their reliance on currents to transport them around, you’ll find them washed up on on the shore quite a lot of the time.
Moon jellyfish range in size between around 10–16 inches (25–40 cm) across their diameter, and have a very clear/transparent appearance. They can be easily identified by their four horseshoe shaped markings that are purple-ish in color.
With their very translucent appearance a moon jelly can be a bit more difficult to spot than some other jellies, especially when you’re in very clear water to begin with.
But thankfully moon jellies aren’t harmful to humans, in fact they have a very mild sting that most people won’t even feel (others may simply feel some mild irritation).
Portuguese Man O’ War
Be wary of the Portuguese Man o’ war. Their long tentacles have been known to wrap around unsuspecting scuba divers and devour them whole..
No I’m only kidding. But they do have very long tentacles though, that part’s true 🙂 – Up to a staggering 165 feet long tentacles in fact!
They can be found in most oceans around the world and are a pretty common jellyfish species in Florida waters.
The top half of them floats above the water, acting as a sail and relying on winds and currents for transport – This is why they can often be found washed up on Florida beaches.
Though they are not actually a jellyfish, the Portuguese Man o War is a siphonophore (which is related to the jellyfish family). It’s a bunch of different organisms that are working collectively together.
The tentacles of the Man o’War can still actively sting you even several days after their death so it’s important that you never attempt touch to one even if it may be dead or else you could get a nasty surprise!
The sting from one of these guys can be very painful. Though there are thousands of cases of stings recorded each year, death caused by Portuguese Man O War are rare, and often the case of a bad allergic reaction to the sting.
I’ve found record of two confirmed deaths due to the Portuguese Man O War; one in Florida in 1987, and the other in Sardinia as recent as 2010. Whilst I did find reference to other deaths (a total of 3 deaths in the United States in total), I unfortunately couldn’t locate the full details of them.
The venom of the Box Jellyfish make it one of the deadliest creatures in the ocean.
They’re named as such because of their box shaped bell, and range in size depending on their species, from as small as your thumb nail, to about 12 inches long with 10 foot tentacles. (Box jellies aren’t bad swimmers either, some reaching speeds of up 4.6 mph!)
The deadliest species of Box Jellyfish are the ones that are found in Australia and the Indo Pacific region, but box jellies can be found throughout the world’s oceans, including the Caribbean, Atlantic and Pacific.
Luckily they aren’t a very common sighting in Florida, and those which you do come across in Florida waters aren’t the truly deadly and terrifying species that you see in the Phillipines.
You should however still exercise extreme caution if coming across one as their sting can be extremely painful, and though rare in these parts, they have the potential to cause a very serious and potentially fatal reaction.
Atlantic Sea Nettle
The Atlantic Sea Nettle is semi transparent, typically pale pink or yellowish in color with white spots and brown stripes, but interestingly this jellies appearance can differ slightly depending on it’s geographical location.
It ranges between 4.0 to 9.8 inches in diameter, and the tentacles of the Atlantic Sea Nettle can reach up to 19.7 inches (50 cm) in length.
It also has four thick, ribbon-like arms inside those tentacles that are what draw food up towards the mouth of this jellyfish.
The carnivorous Atlantic Sea Nettle feeds on plankton, minnows, crustaceons and other jellies!
The sting of the Atlantic Sea Nettle is rated as moderate in terms of pain. It’s not a human killer, though it could induce an allergic reaction, which depending on the person could be very serious.
Cannonball jellyfish (aka cabbagehead jellyfish) are another common jelly that can be found in Florida waters, and washed up on Florida beaches.
They can reach a decent size, and as you probably guessed, they’re named for their round bell which is similar to that of a cannonball.
The bell can reach 10 inches (25cm) in diameter, and it’s also a decent swimmer, using it’s cluster of arms both to aid the cannonball jellyfish in it’s propulsion, but are also for catching prey (which is mainly plankton).
The sting from a cannonball jellyfish is pretty mild and therefore they’re pretty harmless to humans. Their sting can cause minor irritation of the skin like itching, but they would definitely cause irritation to the eye! (so still best not to touch them)
Spider crabs commonly inhabit the bell of the cannonball jellyfish and you can quite often find one hiding inside of one eating the leftover plankton that is caught by the jelly.
Cannonball jellyfish are also commercially harvested as food for humans.
Like the Portuguese Man O War the By-The-Wind Sailor is also not a true jellyfish but a collective of organisms working together in unison.
It also operates like the man o war by relying on winds and currents and is transported by it’s ‘sail’ that sits above the surface of the water. What’s interesting is the direction in which the sail points has been found to be different depending on which part of the world they are.
By-the-wind sailors will leisurely drift around with the currents and tides, and are therefore often found washed up on Florida shores, (sometimes in the hundreds or even thousands), especially after a storm.
It’s stinging tentacles beneath the surface of the water will catch small prey like fish, plankton and invertebrate eggs
They are only small, about 7cm long, and are pretty harmless to humans. Their sting is very mild (if felt at all) and may only cause slight irritation to the skin. You would however definitely want to avoid touching one of these and then touching your eyes!
The pink meanie was only discovered back in the 2000’s in the Gulf Of Mexico. It was then finally classified as a unique species ten years later, and was the first newly classed species of jellyfish since 1921.
This cannibalistic jelly will quite happily feast on other jellyfish, which primarily includes feasting on moon jellyfish.
Using it’s huge 70 foot long tentacles it can ensnare multiple victims at the same time! (As many as 34 jellyfish have been found in a single pink meanie!)
The pink meanie can grow very large and can have a diameter of 3 feet, and whilst it does call the Gulf of Mexico it’s home, and a few do get spotted around Florida beaches it is also quite a rare jellyfish to come across. So if you do happen to see one, make sure you snap a picture of this rare finding!
Cassiopea (Upside Down Jellyfish)
One of the most common types of jellyfish in the Florida Keys, and found often in mangroves is the upside down jellyfish (Cassiopea).
As you can see, it’s name comes from the fact that it’s tentacles face upwards and it therefore has the appearance of looking upside down.
The upside down jellyfish gracefully pulsates through the water and settle on the bottom with their tentacles facing upwards towards the sun.
The algae which lives on the underside (tentacles) of this jelly provides food and nutrients for the jellyfish, but it requires sunlight in order to do this. This is the reason you’ll find them upside down and in shallow and well lit areas within mangroves & coastal areas.
The sting from coming into contact with an upside down jellyfish is very mild, but also it’s possible for them to sting you without even touching you as this jelly will release venom filled mucous into the water, which can sting you if you swim through it!
Probably best to admire these from a distance and to avoid swimming through their venom bombs!
Named because of the mushroom like shape of it’s Medusae, the mushroom jellyfish can sometimes be mistaken for the cannonball jellyfish (which also has no tentacles).
The mushroom jellyfish is larger and flatter than the cannonball, and the cannonball jellyfish also has a distinctive brown edge around the bell which the mushroom jelly does not.
In place of having tentacles, the mushroom jelly instead have 8 oral arms, which it uses to consume plankton.
Due to their lack of tentacles Mushroom jellyfish don’t pose much of a threat to humans, and their stinging cells are located within the inside of their bell.
You would definitely have to try quite hard to get stung by one of these and if you did, then the sting is still considered quite mild.
Mauve Stinger (Purple Jellyfish)
Mauve stingers, aka purple jellyfish can be found all over the world in warm and temperate seas.
It’s a fairly small jellyfish overall, with its bell reaching a diameter of about 1.2–4.7 in, and tentacles that are up to approximately 3 meters in length, and their colors include mauve, pink, light brown and yellow.
Mauve stingers have some interesting characteristics that really set it apart from some of the other jellies on our list, in that both the bell and the tentacles are covered in stinging cells.
It’s also bioluminescent (glow in the dark). It’s glowing is visible during low light when the medusae is stimulated by turbulence (eg. waves), and causes the jellyfish to flash for a brief period.
Though generally not considered dangerous their sting can be very painful, and the pain of the mauve stinger can last a while as well. (Dead purple jellyfish can also sting, so don’t touch!)
This jelly will feed on a wide variety of things, which includes plankton, larvae and fish eggs, and it’s also a cannibal! The Mauve Stinger consuming the young of it’s own is pretty common!
Mauve stingers are very well studied jellyfish, as large swarms of them have been known to wipe out whole entire fish farms.
They’ve also made a nuisance of themselves in the tourism industry as well, with beaches having to be closed due to the large volumes that have invaded them. (It’s not a great swimmer, which is ultimately how large swarms can end up washed up on beaches, or inshore areas).
Protection Against Jellyfish Stings
- Look out for the warning signs or a purple flag which would indicate that there are potentially harmful marine life in the water.
- Know the area prior to entering the water by researching and also talking to the local lifeguard
- Protective layers such as wetsuits, stinger suits, rash guards, rash leggings and protective footwear like dive boots can help to protect you against stings.
- Stay out of the water during jellyfish season when numbers may be particularly high
- Never touch a jellyfish, even if you believe it to be dead