Top 10 facts about jellyfish

In my debut novel, The Thing about Jellyfish, Suzy Swanson — an awkward, methodical 12-year-old who refuses to engage in small talk — learns that her former best friend, Franny, has drowned. Franny was a good swimmer, and no adult can sufficiently explain how something like this could happen. Desperate for answers, Suzy becomes convinced that the true cause of her friend’s death was a rare jellyfish sting. She’s determined to prove it. As Suzy researches her hypothesis, she becomes utterly obsessed with jellyfish.

Obsession with jellyfish? I can relate. The Thing about Jellyfish was born from my own deep fascination with these bizarre creatures. Here are 10 things about jellyfish I learned while writing the book, many of which are stitched into the book’s plot and structure.

1. They look like aliens. Actually, they look like all sorts of things: there’s one species of jellyfish that looks like a neon fried egg, another which looks like Darth Vader, and more than a few that look like party dresses, with endless layers of coloyrful ruffles. They come in all shapes and sizes – from the size of a thumbnail to nearly 40 meters in length. But all of them have a haunting, other-worldly, beauty – like they’ve come from a different world entirely.
2. They’re mindless, like zombies. Jellyfish have no brains. They also have no blood, no bones, no heart. They don’t even have sides – no left side or right side, no back or front. These animals are so different from what we think of as “animals” that that Renaissance scholars actually classified them as plants.
3. They’re dangerous like zombies, too. Jellyfish sting humans at a rate of 150 million per year, which means that in the minute or so it’s taken you to read this far, nearly 500 people have been stung. By the time you’re finished, that number’s going to be about 1,200.
4. Those stings can be as deadly as anything on this planet. Take the Australian box jellyfish, Chironex fleckeri, for example. Considered the most venomous marine animal on Earth, this creature’s sting can cause paralysis, cardiac arrest, and death within a few minutes – barely enough time for a victim to reach shore. Its cousin, Carukia barnesi, known colloquially as the Irukandji Jellyfish, causes such agonizing pain that victims beg for death. It’s the Irukandji that my main character, Suzy, identifies as the true cause of her friend’s drowning.
5. Jellyfish are some of the oldest living creatures on earth… Jellyfish species, it turns out, have been around for at least 600 million years — before dinosaurs or bony fish, before insects or trees, before flowers or ferns or fungi. Jellies have survived five mass extinctions, including the “Great Dying” (the Permian-Triassic extinction), which wiped out up to 96% of marine species and 70% of life on Earth. Jellies are a bridge between simple, ancient life forms, and the wildly diversified life we see around us today.
6. …and they’re likely to stick around for a while. Environmental changes — like warming seas, ocean acidification, and pollution — bring tens of thousands of species to the brink of extinction every year. Perversely, though, those very changes are a boon to jellyfish. In fact, jellyfish populations are now rising so fast that some scientists believe these creatures might one day starve whales to extinction. It’s a fearsome thought: these weird gelatinous creatures, which don’t even have bones or brains, could starve the mighty whale to extinction.
7. Some are downright miraculous. Consider, for example, Turritopsis dohrnii, the “immortal jellyfish.” When stressed, this animal can actually grow younger. That’s not mere metaphor: it is capable of moving backwards through its life cycle, returning to a less mature physical state. This is as if each of us could just refuse to move any further into adulthood and choose to become young children again.
8. We’re learning more about them every day. We know of about 2,000 types of jellyfish, and we’re finding new ones every year. To date, humans have surveyed just 5% to 10% of the oceans — and even less of the deepest parts of the ocean. Some estimate that two-thirds of marine species remain wholly undiscovered.
9. Jellyfish clone themselves. The jellyfish life cycle includes an eerie mix of sexual reproduction and outright cloning. And when a jellyfish is injured, the damaged tissue cells themselves can regenerate as fully-grown jellyfish. Not too long ago, Australian marine biologists left an injured Cassiopea jellyfish alone in its tank…and returned to find it in the company of 200 youngsters, each likely an exact copy of the original!).
10. Jellyfish are a perfect metaphor for adolescence. Like adolescents, jellies are dangerous and fragile — easy to wound, but also capable of inflicting harm. They drift past each other feeling alone and never fully connecting. And like adolescents, they have no idea how beautiful they are.

You can buy Ali Benjamin’s The Thing About Jellyfish from the Guardian bookshop.