Weird Wednesdays: The Rolling Stonefish

Symptoms of stonefish stings include nausea, numbness around the stung area, vomiting, gasping, increased heart rate, intense pain and utter regret that you decided to vacation in Australia. (prilfish/Flickr, Creative Commons)

Symptoms of stonefish stings include nausea, numbness around the stung area, vomiting, gasping, increased heart rate, intense pain and utter regret that you decided to vacation in Australia. (prilfish/Flickr, Creative Commons)

Hello, readers, and welcome to this year’s edition of Weird Wednesdays! Or, perhaps more appropriately, Why You’ll Never Set Foot in The Ocean Again. This week’s topic: the venomous stonefish.

Before we start off, let’s look into some definitions. Specifically, the difference between a venomous creature and a poisonous one. Pleasant, right?

A venomous organism is specifically defined as a something that uses “a specialized delivery system such as fangs to deliver their venom,” according to the Toxicology Education Foundation. Thus, rattlesnakes, cone snails, black widow spiders and your fifth grade teacher are all defined as venomous. Typically, the venom is encased within the animal in a closed system, which means the rest of its body isn’t necessarily toxic.

Poisonous critters, on the other hand, passively secrete a toxin, either in their skin, their muscles or other cellular parts. If you eat or touch it, the toxins are absorbed into your bodily system, wreaking havoc on it.

It’s an important distinction. While a poison dart frog won’t bite you, you still wouldn’t want to pick it up (or kiss it). Rattlesnakes, on the other hand, while being venomous and will bite, are perfectly safe to eat if prepared correctly. (Fun fact: Several towns in Texas will often have “Rattlesnake Roundups” in which they catch rattlers and barbecue them afterwards.)

While there are thousands of poisonous fish in the world (the infamous fugu fish comes to mind), venomous fish are a little rarer, with only about 1,200 species recorded, according to a 2006 study. The most famous (and venomous) is our friend Synanceia verrucosa, the reef stonefish.

The reef stonefish hangs out in the temperate waters of the Indian and Pacific Oceans, north of the Tropic of Capricorn. Its face is permanently affixed in a charming-looking scowl, which has earned it the nickname of “Joe Butcher.” It comes in a variety of colors, including grey, yellow, red, brown, and rust, among others (which we’ll expand on a little bit later).

Its most interesting trait, however, besides having a face only a mother could love, is the fact that it’s the venomous equivalent of stepping on a Lego.

Stonefish are ambush predators. Like mantis shrimp and cone snails, they hang around buried in the sand at the bottom of the reef, looking like an innocuous piece of rock or coral. Their natural coloring helps camouflage them within their environment, hiding their true appearance until they ambush fish swimming above and then swallowing them whole. 

Of course, while its camouflage helps the stonefish stay disguised from its prey, it also helps disguise them from predators, and it prevents hapless seabathers from recognizing what they’re about to step on in the water.

Beachgoers beware, because stepping on a stonefish has painful consequences. The fish has thirteen dorsal spines in its back, each one connected to two venom sacs. When the fish feels threatened, it protrudes the spines, which pierce the foot, often through the boot soles, of whomever was careless enough to tread upon it. Often, more than one spine will pierce the foot, and the pressure will further squeeze out the venom.

Stonefish toxin is nasty stuff. It’s cytotoxic (deadly to cells), myotoxic (affecting the muscles), neurotoxic (affecting the nerves) and cardiotoxic (affecting the heart and blood vessels). It’s a powerful cocktail that blocks calcium channels (which help nerves fire and muscles move), and contains norepinephrine, a neurotransmitter and a hormone that helps trigger the fight or flight response (or a panic attack).

Symptoms of stonefish stings include nausea, numbness around the stung area, vomiting, gasping, increased heart rate, intense pain and utter regret that you decided to vacation in Australia.

While there have been no reported deaths from stonefish venom in Australia, and while there is antivenom available, the experience of being stung is so intensely unpleasant that most people try to avoid it. Tourists are warned to wear reef flats (thick-soled slip-ons for swimming) and avoid stepping in rocky coral areas where stonefish frequent. Or, y’know, just not go to Australia at all. You’d think people would learn by now.

This concludes the week’s Weird Wednesday. I hope you’re all sufficiently horrified, and if you’re not, then I’ll keep trying. See you next week!



Marlese Lessing is the news editor for The Daily Campus. She can be reached via email at marlese.lessing@uconn.edu. She tweets @marlese_lessing.