The word “jellyfish” tends to initiate a similar response in most people – “scream”, “run”, “this is going to hurt”. Being stung by a jellyfish is not pleasant and is something most would prefer to avoid. Our beaches warn us when they are out by flying a purple flag.
When exploring the seagrasses, this is not the first animal people thing they will encounter. Few associate jellyfish with the seagrass community. But within any community there are those we call residents (they reside here) and those we call transients (just passing through). It is the second group that we can place most jellyfish, at least the ones we are concerned about.
The sea nettle.
Photo: University of California at Berkley.
Jellyfish are animals, but not your typical ones. They are obviously invertebrates but differ from most others by having radial symmetry (having a distinct top and bottom, but no head nor tail). They possess ectoderm and endoderm (so, they have a skin layer and some internal organs) but they lack the mesoderm that generates systems such as the skeletal, circulatory, and endocrine. Though they do not have a brain, they do have a simple nervous system made up of basic neurons and some packets of nerve cells called ganglia. They seem to know when they are not in the upright position and know when they have stung something – which initiates the feeding behavior. But they are pretty basic creatures.
When you view a jellyfish the first thing you see is the “bell” and the tentacles – we always see the tentacles. The bell is usually round (radial), could be bell-shaped, or could be flat. It is made of a flexible plastic-like jelly material called mesoglea. Most of the mesoglea is actually water. When you place most jellyfish on the dock and come back in a few hours there may be nothing but a “stain” of where it was. It completely evaporated. There are some exceptions to this, like the moon jelly and the cannonball jelly, who leave thick masses of mesoglea for long periods of time.
Image: Wikipedia.
If you look closer at the “bell” you will see shapes within the mesoglea. Some are stripes, and may have color to them, others look like a clover leaf. These are the gonads of the animal. Jellyfish are hermaphroditic (the gonads can produce both sperm and egg), and they reproduce by releasing their gametes into the water column when triggered by some environmental clue to do so.
Around the edge of the “bell” many have a thin piece of tissue called the velum that can undulate back and forth and allow the jellyfish to swim. Swimming can involve moving up or down in the water column, or turning around, but the swimming action is not very strong and the tide and current actually plays a larger role in where the animals go – like pushing them through a seagrass bed.
Under the “bell” is a single opening, the mouth, that leads into a simple gut (the gastrovascular cavity). This serves as the stomach of the creature. But there is no anus, when the jellyfish has digested its food, the waste is expelled through the same opening – the mouth. This is called an incomplete digestive system.
Jellyfish are predators and hunt small creatures such as baitfish. Though they know whether they are upside down or not, and may be able to detect light, most have no true eyes and cannot see their prey. Some species may be able to detect scent in the water and undulate their velum to try and move towards potential food, but most drift in the water and hope the tide carries them to dinner. To kill their prey, they extend tentacles into the water. These tentacles are armed with stinging cells known as nematocysts. Each nematocyst holds a coiled harpoon with a drop of venom at the tip. They are encased in a cell membrane and are triggered when an object, hopefully food, bumps an external trigger hair that will fire the harpoon. This will then trigger the release of many nematocysts and the potential prey will be “stung” by many drops of venom. The venom can either kill or paralyze the prey at which time the tentacles bring it to the mouth. Many jellyfish have venom that is painful to humans, like the sea nettle and moon jelly, others have a mild venom that we do not even notice. Some have a very strong venom and can be quite painful, like the Portuguese man-of-war which has put some in the hospital. The famous box jelly of Australia has actually killed humans. We do have box jellies in the Gulf of Mexico, but they are not the same species.
This box jellyfish was found near NAS Pensacola in November of 2015.
Photo: Brad Peterman
As the tide pushes these transients through the seagrass meadows, their tentacles are extended and small baitfish like juvenile pinfish, croakers, and snapper become prey. But there are resident jellyfish as well.
With the Phylum Cnidaria (the stinging jellyfish) there are three classes. Class Scyphozoa includes the bell-like jellyfish that drift in the water column with extended tentacles – what are referred to as medusa jellyfish. But there are two other classes that include benthic (bottom dwelling) jellyfish called polyps.
Polyp jellyfish resemble flowers. The “bell” part is a stalk that is stuck to a rock, pier, or seagrass blade. Their tentacles extend upwards into the water column giving the creature the look of a flower. Instead of drifting and dragging their tentacles, they hope to attract prey by looking like a hiding place or other habitat. The sea anemone is a famous one, and a good example of the polyp form. But it also includes corals and small polyps known as Hydra. Hydra are tiny polyps that are usually colorless and can easily attach to a blade of turtle grass. Here they extend their tentacles into the water column trying to paralyze small invertebrates that are swimming by or grazing on the epiphytes found on the grass blades.
The polyp known as Hydra.
Photo: Harvard University.
Another jellyfish that drifts in the current is Beroe, what some call the “football jellyfish” or “sea walnut”. This a relatively small blob of jelly that lacks tentacles but rather has eight rows of cilia/hair (ctenes) along its side that move quickly and move this animal through the water. But like their medusa cousins, not against the tide or current. These jellyfish do not sting, they lack nematocysts, and hence are in a different phylum known as Ctenophora. Kids often find and play with them when they are present, and they are luminescent at night. These stingless jellyfish feed on small plankton and each other and are another transient in the seagrass community.
The non stinging comb jelly.
Florida Sea Grant
There are certainly species of jellyfish to be aware of and avoid. But as you look deeper into this group there are harmless and fascinating members as well. Most of these Hydra are very small and hard to see while snorkeling, but they are there. Another creature to try and find while you are exploring and play “seagrass species bingo”. Have fun and stay safe.
In recent weeks there have been reports of large masses of jellyfish along the Gulf Coast. I have actually heard people state “I would rather be in the water with 100 sharks than 100 jellyfish”. Maybe that is true from some. Honestly, it seems dealing with sharks could be easier. Jellyfish are just there in a swarm. The more you try to move them away, the more they come towards you – it is like trying to avoid the smoke from a campfire.
But jellyfish exist and people sometimes have to deal with them. The thing they hate about them, of course, are their painful stings. As Jimmy Buffett puts it – “They are simple protoplasm – clear as cellophane – they ride the winds of fortune – life without a brain”. This is prreeettttyyyyy close.
Jellyfish are common on both sides of the island. This one has washed ashore on Santa Rosa Sound.
The “cellophane” jelly material is called mesoglea and it is a protein-based material that is 90% water. Lay a jellyfish on a deck and see what is left at the end of the day – not much. The bell undulates rhythmically controlled not by a brain but by a series of nerves – what some scientists call a “nerve net”. At the base of the bell is a single opening – the mouth. There are no teeth and whatever they swallow enters a simple gut where digestive enzymes do their work. But it is the only opening – so, waste material must exit through the same opening. Yes… they go to the bathroom through their mouth. Nice eh…
Then there are the tentacles – those lovely tentacles. These are armed with small cells called nematocysts that harbor a small dart tipped with a drop of venom. Each nematocyst as a small trigger which, when bumped, will fire the dart injecting the venom. When you bump a tentacle, you are literally bumping hundreds of these nematocysts and receive hundreds of drops of venom. Some species hurt, some do not. Those that hurt are no fun.
So, why SO many at one time in one place?
Most jellyfish feed on small food. Those food sources tend to multiple when the water is warm (and it is warm right now) and there are lots of nutrients in the water. When we have heavy rain (and we have had heavy rains this year) the runoff introduces large amounts of nutrients to the system. Warm nutrient rich water mean increase in jellyfish food, which in turn means increase in jellyfish. With winds and tides working together (and we saw this with the recent front that passed through), the jellyfish are shoved into smaller locations. In recent weeks that has been close to shore and the thick masses of jellyfish we have witnessed.
They do fly the purple flags when jellyfish are spotted. It us unusual for them to be a problem on both the Sound and Gulf sides. So, usually if they are bad on the Gulf side, you can move your beach day to the Sound and be fine. And remember – this too shall end. It won’t last forever.
I’d like to be a jellyfish… cause jellyfish don’t pay rent…
They don’t walk and they don’t talk with some Euro-trash accent…
Their just simple protoplasm… clear as cellophane
They ride the winds of fortune… life without a brain
These lyrics from Jimmy Buffett’s song Mental Floss sort of sums it up doesn’t it. The easy-going lifestyle of the jellyfish.
Everyone who visits the Gulf coast knows about these guys, but few people… very few… like them. For most, the term jellyfish signals “pain”, “fear”, and “death”. The purple flag is flying, and no one wants to enter the water. Folks from the Midwest call local hotels and condos asking, “when are the jellyfish going to be there?” It’s understandable. Who wants to spend their week vacation on the Gulf inside a hotel because you can’t go swimming?
I found this along the shore last winter. These are cannonball jellyfish.
I would almost (…almost) rather be diving with a shark than hundreds of jellyfish. When you spot them, they are everywhere. Quietly swarming like ghosts. You push them off and they appear to move towards you – almost like smoke from a campfire, you can’t get away.
They are creepy things. But amazing too!
As Mr. Buffett’s points out, they are simple “protoplasm”. Their body is primarily a jelly-like substance called mesoglea – and most of that is water. If you place a dead jellyfish on your dock and come back that afternoon, you will probably find just a “stain” of where it was – there is almost nothing to them.
The “bell” of the jellyfish is mostly mesoglea. Some jellyfish have thick layers of this, others much thinner. Some have a small flap of skin along the margins of the bell called the velum which they can undulate and swim – but they are not strong swimmers. If the tide is going out, swim as they may… their heading out also.
The bell shaped body of a jellyfish with numerous tentacles.
Many species of jellyfish have interesting markings within the bell. One has a white-colored structure that forms a 4-leaf clover. Another has red triangles all connecting at the center of the bell. For many, these structures are the ones that produce the gametes. Jellyfish reproduce sexually but are hermaphroditic – meaning they produce female eggs and male sperm in the same animal. There is no physical contact between animals, they just release the gametes into the ocean when they are in thick swarms and wah-la… new jellyfish – many new jellyfish.
On the bottom of the bell is a single opening that leads to a single pouch. This opening is the mouth, and the pouch is called the gastrovascular cavity. Jellyfish are predators – carnivores. There are no teeth, and most do not seek their prey – their prey finds them. Hanging from their bell are the tools of the killing trade, the part of this animal we do not like… the tentacles. Some tentacles can extend for several feet beyond the bell, others you can hardly notice them – but this is where the killing happens.
Along the tentacles there are small capsules called cnidoblasts which contain small cells called nematocyst. These nematocyst contain a coiled dart which at the end contains a drop of venom. There is a trigger associated with this cell. The jellyfish does not fire it – instead, the prey bumps the trigger and the nematocyst “fires”. The drop of venom is injected, along with the hundreds of other nematocysts along the tentacle the fish just bumped. This venom paralyzes the prey, other tentacles coil around it firing more nematocysts, and the tentacles retract towards the mouth – bingo… lunch.
This box jellyfish was found near NAS Pensacola in November of 2015. Photo: Brad Peterman
Of course, the same happens when people bump into them. For us it is painful and unpleasant – but we are not consumed. That said, some species are quite painful. Some will force people to the hospital, and some have even killed people. The Box Jellyfish is the most notorious of these deadly ones. Known for their habits in Australia, there are at least two species found in the Gulf. The ones found here are not common, and there are no reported deaths, but they do exist. The Four-Handed is the one more widespread here. It actually has eyes, can detect predators and prey and swim towards or away from them, and the male fertilizes the female internally – not your typical jellyfish.
The more familiar painful one is the Portuguese Man-of-War. This creature is more like a sponge in that it is not just one creature but a large “condo” of many. Some cells are specialized in feeding, these are found on their long tentacles. Others specialize in reproduction; these are found near the blue colored air bag. They produce this blueish colored air bag which is exposed above the surface. The wind pushes on the bag like a sail and this moves the creature across the environment in search of food. Hanging from the bag are long tentacles which are made up of individuals whose stomachs are all connected. So, when one group of cells makes contact and kills a prey – they consume it and the tissue is moved through the connecting stomachs to feed the whole colony. To feed a whole colony, you need a big fish – to kill a big fish, you need a strong toxin, and they have it. These are VERY painful and have put people in the hospital, some have died. Some say that the Portuguese man-of-war is not a “true” jellyfish. This is true in the sense that they belong to a different class of jellyfish. There are three classes, the Scyphozoans being what we call the “true” jellyfish – Portuguese man-of-wars are not scyphozoans, but rather hydrozoans.
The colonial Portuguese man-of-war. Photo: NOAA
Another interesting thing about jellyfish, is that they are all not jellyfish-like. As we just mentioned, there are two other classes and one other phylum of jellyfish-like animals. Hydrozoans and anthozoans are not your typical jellyfish. Rather than being bell-shaped and drifting in the ocean looking for food, they are attached to the seafloor and look more like flowers. Their tentacles are usually smaller but do contain nematocysts. Their toxin can be strong, some do eat fish, but most have a weaker toxin and feed on very small creatures – some only eat plankton. These would include the hydra, sea anemones, and the corals. As mentioned above, this also would include the Portuguese man-of-war.
Comb jellies are those jellies that drift in the currents and have no tentacles. We commonly collect them and toss them at each other. When I was growing up, we referred to them as “football jellies” because of this. The reason they do not sting is not because they do not have tentacles (some species do) but rather they do not have nematocyst and cannot. Rather they have special cells called colloblast that produce a drop of sticky glue at the end which they use to capture prey. Not having toxins, they cannot kill large prey but rather feed on smaller creatures like plankton and each other – they are cannibals. For this reason, they are in a whole different phylum.
The nonvenmous comb jelly. Photo: Bryan Fluech
The jellyfish of the Gulf are a nuisance at times but are actually amazing creatures.
I have played in the waters of the northern Gulf of Mexico all of my life… but I have never heard of this – “sea lice.” It has been in the news recently and I have had a couple inquiries concerning it so I decided to investigate.
A few weeks ago there was a report of “sea lice” in Walton County. Bathers were leaving the water with a terrible skin condition that was itchy and painful, particularly in areas beneath their bathing suits. Photos of this show a series of welts over the area – almost like a rash. What was causing it? And what can you do about it?
Illustration of the “thimble jellyfish”. Graphic: University of Michigan
My first stop was Dr. Chris Pomory, an invertebrate zoologist at the University of West Florida. Dr. Pomory indicated that the culprit was most probably the larva of a small medusa jellyfish called the thimble jellyfish(Linuche unguiculata), though he included that it could be caused by the larva any of the smaller medusa. Dr. Maia McGuire, Florida Sea Grant, told me a colleague of hers was working on this issue when she was in grad school at the University of Miami. Published in 1994, it too pointed the finger at the larva of the thimble jellyfish. Here I found the term “Sea Bathers Eruption” (SBE) associated with occurrences of this. I also found another report of SBE from Brazil in 2012 – once again pointing the finger at the thimble jellyfish larva. So there you go… the most probable cause is the larva of the thimble jellyfish. Note here though… Dr. McGuire indicated that SBE was something that was problematic in south Florida and the Caribbean… reports from the northern Gulf are not common.
So what is this “thimble jellyfish”?
Most know what a jellyfish is but many may not know there are two body forms (polyp and medusa) and may not know about their life cycles. The classic jellyfish is what we call a medusa. These typically have a bell shaped body and, undulating this bell, swim through the water dragging their nematocyst-loaded tentacles searching for food. Nematocysts are small cells that contain an extendable dart with a drop of venom – this is what causes the sting. Nematocysts are released by a triggering mechanism which is stimulated either by pressure (touch) or particular chemicals in the water column – hence the jellyfish cannot actually fire it themselves. The thimble jellyfish are dioecious, meaning there are male and females, and the fertilized eggs of the mating pair are released into the ocean. These young develop into a larva called planula, and these seem to be the source of the problem. Drifting in the water column they become entrapped between your skin and your bathing suit where the pressure of the suit against the skin, especially after leaving the water, causes the nematocyst to fire and wham – you are stung… multiple times. The planula larva are more common near the surface so swimmers and snorkelers seem to have more problems with them.
So what can be done if you encounter them?
Well – there are two schools of thought on this. (1), go ahead and stimulate the release of all nematocysts on your body and get it over with or (2) do everything you can to keep any more nematocysts from “firing”. Some prefer #1 – they will use sand and rub over the area where the jellyfish larva are. This will trigger the release of any unfired nematocyst, you will deal with the pain, and it will be over. However, you should be aware that many humans have a strong reaction to jellyfish stings and that firing more nematocysts may not be in your best interest. Some will want to take a freshwater shower to rinse them off. This too will trigger any unfired nematocysts and you will be stung yet again. Using vinegar will have the same response as freshwater.
So what do you if you DO NOT to get stung more? Well… the correct answer is to get the bathing suit off and rinse in seawater that DOES NOT contain the larva… easier said than done – but is the best bet.
Is there any relief for the pain and itch?
Dr. McGuire provided the following:
Once sea bather’s eruption occurs (and you have taken off your swimsuit and showered), an application of diluted vinegar or rubbing alcohol may neutralize any toxin left on the skin. An ice pack may help to relieve any pain. The most useful treatment is 1% hydrocortisone lotion applied 2-3 times a day for 1-2 weeks. Topical calamine lotion with 1% menthol may also be soothing. Nonsteroidal anti-inflammatory drugs such as ibuprofen and aspirin (but not in children) may also help to reduce pain and inflammation. If the reaction is severe, the injured person may suffer from headache, fever, chills, weakness, vomiting, itchy eyes and burning on urination, and should be treated with oral prednisone (steroids). The stinging cells may remain in the bathing suit even after it dries, so once a person has developed sea bather’s eruption, the clothing should undergo machine washing or be thoroughly rinsed in alcohol or vinegar, then be washed by hand with soap and water. Antihistamines may also be of some benefit. Other treatments that have been suggested include remedies made with sodium bicarbonate, sugar, urine, olive oil, and meat tenderizer although some of these some may increase the release of toxin and aggravate the rash. Symptoms of malaise, tummy upsets and fever should be treated in the normal fashion.
This is a “new kid on the block” for those of us in the northern Gulf. It has been in south Florida and the Caribbean for a few decades. As the Gulf warms, more outbreaks may occur, there is really not much to be done about that. Hopefully most reactions will be minor, as with any other jellyfish sting.
Summertime and swimming at the beach just go together naturally in Florida with our state’s more than 1,000 miles of coastline. Many fond memories are created along these salty margins and the Panhandle region of the state has some of the top-rated beaches in the world. It is a great place to experience a relaxing, cool dip in the Gulf of Mexico on a balmy summer day. One thing to be aware of though is the possibility of an encounter with one of the Gulf’s “stinging” inhabitants and what to do if this occurs.
The Moon Jelly is a Common Inhabitant Along Panhandle Shores. Photo courtesy Florida Sea Grant
There are actually several different organisms that have the capability to sting. This is primarily their mechanism for capturing food but it may also serve to deter predators. Most belong to a group of organisms called “Cnidarians,” which includes the jellyfish. Most jellyfish are harmless to us and are important food sources for many other marine creatures, including some sea turtles, fish and even other jellies! Some species are even dried, shredded and eaten by humans. However, there are several types of jellyfish that will inflict a sting when brushed against and some that are actually a serious hazard. Keep in mind that people also react differently to most venoms, exhibiting varying degrees of sensitivity. The most dangerous types include some of the box jellyfish species (visit HERE for general map of worldwide jellyfish fatalities), and the blue-colored Portuguese man-o-war, which is sometimes common on our shores after sustained southerly winds during summer. A few of our locally common species that cause pain but of a generally less-severe nature include the moon jelly, sea nettle, and cannonball jellyfish. We even have some species of hydroids that look very much like a bushy brown or red algae. They are usually attached to the bottom substrate but when pieces break off and drift into the surf they can provide a painful encounter.
If you are stung there are a couple of things you can do to help and a couple of things you should not do. First, move away from the location by getting out of the water so you don’t encounter more tentacles. Carefully remove any visible tentacle pieces but not with your fingers. You should also change out of swimwear that may have trapped pieces of tentacles or tiny larval jellyfish against the skin. Do not rinse the area with fresh water as this causes the remaining stinging cells to fire their venomous harpoons. If symptoms go beyond a painful sting to having difficulty breathing or chest pain you should immediately call the Poison Information Center Network at 1-800-222-1222 or call 911.
Another thing to watch for in areas where public beaches display the beach warning flag system is a purple flag. This flag color at the beach indicates dangerous marine life and quite often it is flown when jellyfish numbers are at high levels. All of this is being written, not to scare you away from our beaches, but to help you enjoy our beautiful coastline with a little better understanding of what is out there and what to do if you happen to have a brush with a jellyfish. The vast majority of encounters are a minor irritation in an otherwise pleasant experience.
