One of my most painful experiences free-diving involved an unexpected scuffle with a nearly invisible creature that had no eyes, no brain, no heart, no circulating blood, and no spine. Yet somehow it managed to best me, and I have all those things! It was over 20 years ago, but I still remember the chilling effects from the thousands of tiny nematocysts (stinging cells) released by the cloud of thimble jellyfish larvae I swam through. After diving deep on a free-dive, I began to surface, but a translucent cloud blanketed me in all directions. I had no choice but to push through this mystery phenomenon or stay in Davey Jones’s locker forevermore. As I surfaced, it became clear that this cloud was a living swarm of jellies! With no good options, I swam under and through them multiple times on my way to the boat. “It wasn’t so bad,” I told myself kicking onto the boat, “phew, crisis averted.” But slowly as the day went on, a rash began to form anywhere my skin was exposed. By midnight, I was running a 103 fever, nauseous, and cursing Poseidon himself for surely these creatures were otherworldly underwater demons.
This was, of course, before I truly understood and appreciated how jellyfish are fascinating marvels of simplicity, engineering, and even enlightenment. Critical components that have allowed these ancient creatures to survive for over 500 million years. Apparently, brains only get you so far. But being really dumb and, basically an invisible stomach, you can really run with that, as jellyfish have come to dominate huge ecosystems throughout the ocean, by doing nothing more than hiding in plain sight. And although they may lack higher order skills and complex survival tools of fish and sea-going mammals, jellies are perhaps our greatest marine teachers. They are a gelatinous canary in a coal mine for the climate crisis, critical species extinctions, and habitat destruction. But only if we listen closely, as they are very silent masters of subterfuge washing up next to you before you even realize what is happening. The question is—are we too smart, too complicated, to hear and heed their simple lesson?
But first, what really is a jellyfish? Is it more fish, more jelly, or neither? Born out of the Cambrian explosion of life, 250 million years before the first dino-“roars” would echo across the ages, jellyfish have survived through simplicity. Among the very first animals on Earth, they learned to float on the ocean’s good graces, going wherever the currents take them. While many do have simple jet or rowing motions, this serves mostly for small up and down movements and the intake of unsuspecting prey. So, they are indeed much more jelly, and not at all like fish. However unimpressive, these primitive mechanisms of locomotion are potentially the first attempts of any animal on Earth to move. They are the wheel of the ocean, still spinning away today! To see a jellyfish, is to witness the epic struggle of life bursting free into the glorious wild cacophony of dynamic motion that defines our natural world. Swimming with a jelly is nothing short of magical underwater time travel.
“Jellyfish stings are probably their most complex and mindblowing mechanism. Located on the tentacles are thousands of tiny stinging cells called cnidocytes.”
Of course, try not to get stung. Jellyfish stings are probably their most complex and mindblowing mechanism. Located on the tentacles are thousands of tiny stinging cells called cnidocytes. These passive stingers help to defend the jelly as well as stun their smaller prey. If touched, tiny, microscopic needle-like harpoons (nematocysts) shoot out of the cell within a millionth of a second—one of the fastest actions in nature. The harpoon has a small coil attached to it, injecting venom with the pressure of a bullet. Amazingly, jellies have a kind of biological algorithm controlling this process so only the right type of motion activates a release, otherwise they would be constantly injecting their own tentacles. Depending on the species, stings produce a small rash or a quick death, if left untreated. So, it is wise to know what types are in the water before swimming.
Thankfully, jellyfish can also bring plenty of positive benefits to humans. Recently, scientists have been studying their venom for its unique ability to halt cancer cell growth in humans. And beyond their vital role in the ecosystem, they have revolutionized science and medicine. Jellies have a unique glowing compound called Green Fluorescent Protein, “GFP” for short. In a flash of brilliance, scientists discovered they could encode this glowing protein into genes allowing them to see how genes express themselves down the line. This discovery opened a new horizon of biological and medical research to study disease and biological processes so profound it earned the Nobel Prize in 2008. And more amazingly, jellies might even hold the key to immortality. Or at least help you knock off a few years. Huge advances in recent decades have shown promising research into the reversal of aging as a viable cure for disease. Turritopsis dohrnii, known as the “immortal jellyfish,” has helped anti-aging researchers deepen their understanding of epigenetics (the biological levers that turn genes on an off) as this simple little jelly can transform its existing cells into a younger state to survive starvation, physical damage, or other stressors. It is jellies’ simplicity that makes them ideal for studying basic cellular biology. They possess magical cellular superpowers, including limb regeneration, that are helping scientists unravel the mysteries and potential of the human genome.
And like all great magic, jellies are accompanied by a brilliant display to distract the eye. They use an enchanting form of bioluminescence to distract predators and lure prey. Whom do you think magicians got the idea from? These light shows are hypnotic and alien. One of my absolute favorite activities during a night dive (hopefully a dark moonless night) is signaling “lights out” to my group. It takes a second, but as your eyes peer out, adjusting to the immense blackness of the silent sea, life erupts in all directions. Creatures, including jellyfish, speak to each other through brilliant spectrums of flashing blue, green, and red color explosions. All sequenced, perfectly evolved to harness the ancient power that all cells possess, even human, to create low levels of light. Simple, elegant, and mysterious.
But if they’re so ancient and so simple, how have they survived when most other creatures died off or out-evolved them? The simple answer is sex. Jellyfish are masters of making more jellyfish. Upwards of 40,000 eggs can be released daily by an individual jellyfish. Jellyfish blooms can consist of hundreds of millions of individuals. Some jellyfish start producing more jellyfish only days after they are born. It’s all about numbers. And because they are so simple, they can tolerate a wide variety of ocean conditions where other more complex creatures would perish. And despite their simplicity they do something very clever. Once a jellyfish egg and sperm meet, they form a larva that drops to the sea floor and attaches onto a hard structure creating a jellyfish polyp. Scientists believe this polyp stage has the ability to wait days to years before releasing not just one, but multiple juvenile jellyfish buds into the water column when conditions are favorable.
It is these incredible reproductive abilities that distinguish jellyfish as a harbinger of danger much greater than a minor sting. For millions of years jellyfish have occupied a critical niche within the ocean. Due to their great numbers and large breadth of tolerable ocean habitats, they provide a food base for a huge amount of ocean creatures. This movement of energy and nutrients through the ocean food web is a critical phase of the larger biogeochemical cycle that maintains a healthy balance of earth life, the same one we evolved humans rely upon for food, air, and water. A disruption is catastrophic. Like a coal miner running away from a dead canary, if we see too many jellies, society better get moving—something has gone terribly wrong.
Why? Because jellyfish are ancient survivors. They don’t mind going back to the way things were—when the Earth wasn’t habitable for humans. As the oceans warm to levels not seen in ages, we are witnessing huge explosions in jellyfish populations. As we decimate larger predators higher on the food chain, we witness huge explosions in jellyfish populations. In the over 400 oceanic dead zones no longer suitable for life across the planet, we witness huge explosions in jellyfish populations. And in regions where jellies aren’t normally found such as the Black Sea, in little under a decade, we have witnessed explosions in jellyfish populations. These types of explosions create a catastrophic decline in zooplankton populations, an important jellyfish food source. This creates a cascading effect allowing algal blooms, previously controlled by the zooplankton, to explode, thus decimating the foundation of our food webs and potentially destroying whole ecosystems. Keep in mind, these ecosystems provide 50% of the oxygen you just inhaled. And worst of all, once jellies take over an ecosystem it is extremely difficult, often impossible, to reverse course. These masters of minimalist adaptation can survive with little resources in even the worst environments. Jellyfish overpopulation is a harbinger of a time when planet Earth was not compatible with you and me. So this simple creature has a simple lesson; but are we too evolved, have our societies become too complicated to notice their ancient wisdom? Hopefully not. We will heed their warning and will continue to value the insight they offer and their magical magnificent presence out among the waves.
Cool Jellyfish Facts
- Some jellies are so fragile they are almost impossible to collect and study.
- The longest creature on Earth is the lion’s mane jellyfish. It grows up to 120-ft long.
- Many jellyfish species are edible.
- The box jellyfish known as Chironex fleckeri is the world’s most venomous animal.
- Roughly 4,000 species in the jellyfish subphylum Medusozoa are found in the ocean, only 50 species from the class Cubozoans, or box jellyfish, are considered highly fatal.
- The deadliest box jellyfish can kill a human in 2-5 minutes.
- About 150 million people are stung by jellyfish each year.
- At least 100 people die from box jellyfish stings each year, but the actual number is probably much higher.
- Some jellyfish, like the box jelly, have evolved true eyes (up to 24) surrounding their head, allowing them to see in 360-degree.
- Although many species are commonly considered jellyfish due to their similarities, there are only about 200 species of “true jellyfish” in the class Scyphozoa.
What to Do If Stung by a Jellyfish?
The first and best action is to avoid getting stung, which means find out if certain times of the year or month have more jellies. Next, learn the local species in your area so you can identify how cautious you need to be around them, and consider wearing rashguards or thin wetsuits to minimize your exposure.
Never touch a dead jelly—the stinging cells remain active long after the creature dies. If stung, peeing on someone is a terrible idea. Mainly because you are either peeing or being peed on by someone. More importantly, it won’t help with the venom. The first action is to remove any tentacles or stingers still in the skin, but not with your hand, as this will sting your hand. Next, use warm to hot water and soak and wash off the area thoroughly. If you are stung on large areas of your body (half an arm) or exhibit signs of a worsening reaction from a small sting (difficulty breathing, severe pain lasting longer than 2 hours, large swelling, vomiting) seek emergency medical treatment immediately. Most stings are harmless, but rarely they can be fatal, so treat them accordingly. Debate exists within the scientific community as to whether vinegar actually works on stings. But don’t pee, use baking soda, or rub the area, it may only cause more stingers to fire. Most importantly, avoid any jellyfish that looks like a box (cube) with a tentacle hanging off each corner (four total) of the box. That’s a box jelly.
Jellyfish Found in Hawai’i
Three species of box jellyfish are found in Hawai‘i, but they are generally not fatal to humans unless an individual is allergic. They are an elongated cube shaped with one tentacle hanging from each side of the cube. High wind conditions can sometimes blow them in, and specific times of the month or year correspond to their life cycle. They typically arrive 9-12 days after a full moon, so consult your moon phases.
These beautiful jellies have a full-moon-shaped head, up to 16 inches, and short fringe-like tentacles. They are generally harmless to humans, but still give a little sting so be wary.
With a 4-12 inch bulbous head and club like tentacles, these jellies have a characteristic brownish-yellow color due to the symbiotic photosynthetic algae that live in their tissues—just like the colorful coral reefs.
Portuguese Man O' War
Although technically not a true jellyfish, these clonal organisms have a small bluish to purple asymmetric bubble on their colorful head and short to long (up to 100-ft) colorful tentacles. They are generally not fatal but pack a big sting, avoid them if you can.