An excerpt from 99 Ways to Die: And How to Avoid Them.

In response to this chapter, I expect to receive a battery of soaking wet letters from infuriated marine biologists, since each species deserves their own chapter, but my editor cut me off.

Flamboyant cuttlefish

The flamboyant cuttlefish is not to be confused with the flamboyant cuddle-fish, which does not exist. The cuttlefish, Metasepia pfefferi, looks like an orchid that ran away from its stem to become a fish. Everyone has dreams.

Found in the shallow sands of tropical waters of Australia and Southeast Asia, flamboyant cuttlefish live up to their name by putting on an ostentatious show to attract the ladies by changing the colors and psychedelic patterns on their skin. It’s OK to show off when you are one of the most poisonous animals in the sea. The good news is, as long as flamboyant cuttlefish isn’t on the menu, you’ll be just fine. These marine mollusks are poisonous, not venomous, so you would have to ingest them to die. There are many places where cuttlefish is on the menu, just make sure it’s not the flamboyant one.

Striped pyjama squid

We need to work on the names of deadly marine life. For instance, this guy is named like he’s ready for a sleepover but is a serial killer. Additionally, the striped pyjama squid is not even a squid. The nomenclature is absurd.

While the name may be incongruous, the choice of clothing is slightly more appropriate, as this fish is dressed in black and white stripes, like a 1920s chain-gang escapee. This stripped cuttlefish is having his O Brother, Where Art Thou? moment, except this convict has no problem getting caught. Like many cephalopods, the pyjama squid can camouflage by changing color, but if he doesn’t feel like changing colors, he’ll just hit you with his venom. Striped pyjama squid is both poisonous (so don’t eat it) and venomous, secreting a toxic slime that can paralyze humans. I suppose I should mention that the striped pyjama squid is found in Australia, but it feels redundant. I will abstain from describing the bizarre way these Indo-Pacific cephalopods breed. This is not one of your BookTok romance novels; this is lifesaving literature.

Blue-ringed octopus

After surviving a lethal pandemic, a Virginian woman took a relaxing trip to Bali. She posted a video to social media of her and her friends passing around a tiny octopus with blue-ringed spots, and the video quickly went viral as the internet collectively shouted, “Put it down!”

She was holding a blue-ringed octopus, and she was lucky it was having a good day. As adults these potent portables never get much bigger than a kiwi fruit, but have enough toxin to kill 26 humans in a matter of minutes.

Their painless bite delivers tetrodotoxin, similar to the poison in pufferfish meat, that blocks muscle cells including the breathing muscle of the diaphragm. There is often no sign you’ve been bitten until it is too late. But thanks to this book, your next Bali vacation is less likely to be ruined by this blue-ringed baby.

Barracuda

Ooh, barracuda,
Heart’s infamous carnivore,
Little Queen of seas.

It felt like the right moment for a haiku. No fish inspires music and death poetry like the barracuda. This sawtooth predator is often cast as a maleficent villain, and that is because it is. The great barracuda grows to six feet, but the smaller species can be just as deadly, living in groups called batteries. The slender fish have torpedo-like speed, going from zero to over 30 miles per hour in seconds, attacking their prey in a self-explanatory method known as ram-biting.

Barracuda prefer clear, warm, coastal waters, hunting near reefs and seagrass. This big kahuna is present in Hawaii as well as the Eastern Seaboard, frequenting the coasts from North Carolina to Florida. Attacks by barracuda are rare but have been documented, including attacks in Key West and North Carolina. While they don’t attack humans often, it’s best not to test a barracuda.

And if the barracuda’s bite wasn’t vicious enough, this vindictive fish will come back to haunt you even after death. If you manage to catch and eat a barracuda, they can carry a type of fish poisoning known as ciguatera, which is a whole ‘nother chapter.

These saltwater fish are not to be confused with South American freshwater piranhas, which have also killed humans. Piranhas are carnivorous fish, native to the Amazon, which hunt in schools participating in feeding frenzies. They are attracted to splashing water and blood. Actually, go ahead and confuse the two types of fish; they have similar styles, just different salinity. To avoid an attack, stay away from these fish with sharp teeth, and exit the water when bleeding.

Cone snail

Sally sells seashells by the seashore but purchase with caution because one of those shells could kill you. Turns out Sally is a bit of a sociopath. This particular shell may be Mother Nature’s retaliation for humans absconding with millions of shells from her sandy shores to decorate ocean-themed bathrooms.

It’s not actually the shell that’s lethal but what’s inside: the cone snail. Found in tropical waters of the Indo-Pacific, nothing about this snail is slow. In fact, this carnivorous snail shoots a lightning-fast harpoon full of a toxic cocktail that paralyzes victims instantly. The harpoon is generally meant for fish, since the five-inch snail has yet to eat a human, but the snail slightly overshot the potency of its toxic cocktail, so if a human is harpooned it can cause total body paralysis, including paralysis of the muscles needed to breathe, resulting in death. With immediate medical care, breathing can be supported with a ventilator and the toxin effects reverse in several days.

The cone-shaped snail’s shells tend to be intricately patterned and beautiful, so you’ll want to pick them up, but don’t do it. It is a trap. If diving or swimming in tropical waters of the cone snail, you should know what they look like and avoid them. It is also recommended to wear shoes at the beach, so everyone knows you’re a tourist but also to avoid stepping on a cone snail. Lastly, there is an old adage that if you hold a seashell to your ear, you can hear the ocean, but you can also get a deadly cone snail harpoon in your ear, so leave the shells on the sand and keep swimming.

Electric eel

The electric eel is catfishing you, because this Amazonian river knifefish is not even a real eel. But it is electric. This freshwater fish is so hot it managed to boogie-woogie its way into a chapter for ocean creatures.

These eels can grow up to eight feet long and emit a constant 10 volts but can quickly power up skin cells called electrocytes. Electric eels can generate up to 800 volts of electricity, meaning they have the same shocking electrical potential as a car battery. Currents above 500 volts are considered high voltage, meaning they can cause deep burns and cardiac arrhythmias.

A standard household power outlet is 120 volts, and while I was Googling this simple fact for comparison, I became concerned by the number of Reddit threads dedicated to questioning the safety of sticking cutlery into power outlets. The answer is “no,” it is not safe to stick a fork in a power outlet.

There are documented human deaths by electric eels, usually due to drowning or cardiac arrest after multiple shocks. The probability of encountering an Amazonian electric eel for many is slim to none, but most people have unfettered access to power outlets and forks, so maybe I should do a chapter on that?

Nudibranch

Nudibranchs are tiny colorful sea slugs. They are extremely festive, decked out in elaborate neon-colored ruffles, tassels, and fringe. In the wild, if an animal is easy to see, it is usually because they have no need to hide. These kids are the wilderness equivalent of RuPaul’s pride parade float, there to be seen, but the background music is blaring loud and clear, “Can’t Touch This.”

Nudibranchs steal jellyfish toxin, ingesting it and adding it to their arsenal. They take the jellyfish stinging cells, swallow them, then excrete them onto their backs. Some nudibranchs make their own toxins but when you are this good-looking, someone will let you copy their work. Ask any high school student.

The high school quarterback of nudibranchs is Glaucus atlanticus, but all his friends call him the blue dragon. He copies the homework of one of the deadliest creatures in the sea, swiping stinging cells from our next guest, the Portuguese man o’ war.

Portuguese man o’ war

Not only is the Portuguese man o’ war not a jellyfish, but it is a they. The man o’ war is a siphonophorae which is a complex of multiple organisms living together as one being. Colonies of genetically identical clones called zooids join together to create one living organism, like a homicidal flashmob.

The P. war looks like a floating kidney with tentacles, colored in translucent purple and blue, well actually, “It’s not just blue, it’s not turquoise, it’s not lapis, it’s actually cerulean.” And for macabre style points, the man o’ war fills its cerulean floaty up with carbon monoxide gas, because why use air when you could use a poisonous gas?

They float on the surface of the sea buoyed by gas-filled bladders called pneumatophores that resemble 18th-century warships, which is how they got their name. These warships are reliant on atmospheric pressures to sail. Ocean currents create armadas of thousands of man o’ war pneumatophores, drifting together on the sea surface, with deadly tentacles swaying up to 165 feet below.

If a human touches a tentacle, which is not uncommon on the U.S. Atlantic seaboard, the sting will cause pain, swelling, and rope-like hives. Symptoms can progressively worsen to collapse of the cardiovascular system and death.

If stung, remove the tentacles with tweezers or a gloved hand. The next steps have some conflicting studies but a 2017 study by the University of Hawaii showed vinegar stopped further discharge of the man o’ war stingers, and recommended soaking the affected area in hot water. Alternatively, the U.S. Department of Defense paid Alatalab to develop StingNoMore spray that works for man o’ war envenomation, but then didn’t tell anyone about it, so now you know.

Ashely Alker is an emergency physician and author of 99 Ways to Die: And How to Avoid Them.