My Appreciation for Walking Armoured Beach Frisbees

Pedro Hay

There is a good chance many people read that title and immediately threw their copy of Salient into the bin, because surely nothing good can come from an article with such a nonsensical bullshit headline. It sounds like something clearly cooked up by a dangerous raving maniac. 

Well, unfortunately for those people, they will now never know what makes these frankly insane creatures so special. They will not understand why they matter, why we should care about them, or how there may even be some life advice hiding beneath their armoured little shells. 

The horseshoe crab—yes, a much more boring name than “walking armoured beach frisbee,” but what else was I meant to do, gently invite your attention?—is an armoured little tank of a specimen that belongs to the phylum Arthropoda. That group includes insects, crustaceans, arachnids, and other weird creepy things with too many legs. Despite its name, the horseshoe crab is actually more closely related to spiders than to anything you would reasonably expect to find in a seafood platter. There are only four surviving species of the horseshoe crab today, mostly found across South and East Asia, with one species living along the Atlantic coast of Northern America. 

As far as lifestyles go, horseshoe crabs are basically living Mortal Engines. They crawl around the ocean floor on their six walking legs, pinching up whatever small prey they come across before shoving it into the grinder on their underside. Cute! 

This grinder is made of bristly structures called gnathobases, located at the base of their legs, right where the legs meet the body. As the crab walks, its legs move in opposite directions, grinding the gnathobases together while pushing food toward its mouth. Basically, the horseshoe crab spends all day scuttling around with an industrial shredder attached to its stomach.

You’ve got to respect a creature that is, quite literally, always on the grind.

By now, you may be thinking, “Oh my god, these things are screwed up, what could be so important about these freaks?” To which I reply: you are being SO impatient and, quite frankly, rude. I’m getting there. 

First of all, horseshoe crabs have been around for a LOOONG time. The tuatara outside the TTR block? Infantile compared to these guys. Horseshoe crabs have remained practically unchanged since the Triassic period, around 250 million years ago. Fossil evidence from similar ancestral species suggests their lineage may stretch back even further, to roughly 445 million years ago. That would mean these little bastards were crawling around before trees existed. 

Somehow even wilder than that, horseshoe crabs also carry a secret goldmine inside their creepy little bodies; something so ridiculous it sounds like I'm making it up. 

They have bright blue, medicinally valuable blood. 

Horseshoe crab blood is copper based, giving it a vibrant blue colour—the complete opposite to our red, iron-based blood. And while looking like “liquified Smurf” is already interesting enough, this blood is far more than a freaky party trick. It contains cells called amoebocytes, which are crucial in testing vaccines and other medical products for bacterial contamination. Specifically, blood from the Atlantic horseshoe crab is used to create a clotting agent called limulus amoebocyte lysate, or LAL. 

For decades, LAL has been used to test vaccines for dangerous bacterial toxins. When contamination is present, LAL clots around it, acting like a tiny biological fire alarm. In other words, the blood of this weird ancient frisbee-spider has helped keep modern medicine safe.

Naturally, because this blood is extremely valuable—worth thousands of dollars per litre—humans did what humans do best and exploited the hell out of these beautiful creatures. Creatures, by the way, that have existed peacefully on this planet for FAR longer than we have.

Every year, more than 1 million horseshoe crabs are hauled out of the ocean and taken to biological facilities to be bled. There, they can have up to 30% of their blood drained by machines that sound, quite frankly, like something a vampire would design. 

An estimated 10% to 15% of horseshoe crabs die during the bleeding process, and scientists suspect even more die after being released back into the ocean. It does not take a marine biologist to see how grim that is. 

The good news is that research centres around the world have been developing alternatives to LAL. These alternatives do not require sucking these poor little things dry. Thanks in part to this process, horseshoe crab populations in parts of North America are beginning to recover, slowly clawing their way out of the “vulnerable” category.  

Yay. Finally, some good news. 

But before we all start jumping for joy and clapping like the credits are about to roll, it is time to sit back down. Because, of course, it is not all peaches and cream.

Across Asia, horseshoe crabs are still in serious trouble, driven down by overfishing, pollution, and habitat loss. The tri-spine horseshoe crab, despite having an objectively badass name, is now considered extinct in Taiwanese waters. Across much of greater Asia, its populations continue to slide toward deeper endangerment each year. 

Depressing, I know. I did not want to end this piece there, because while it is easy to sink into the despair of what can feel like an impossible fight against humanity’s casual disregard for nature, there is still hope. Annoying, stubborn, inconvenient hope.

There is always something that can be done. 

Next time you are at the supermarket, maybe skip the can of tuna. It smells weird anyway. Take power away from the fisheries that keep pushing further into the habitats of our ugly little scuttling marine friends. Go to the conservation talk advertised outside the lecture hall you have been avoiding. Look online and find out what you can do, even if it feels tiny. Especially if it feels tiny.

Do not let hopelessness consume you. Be like the horseshoe crab. Get up every day and keep crawling. Keep moving forward. Maybe even keep shoveling small worms into your terrifying grinding stomach-mouth. Progress does not always have to be graceful. Sometimes, it just has to keep going.

P.S: They can backflip. 

Yes, I saved that until the very end. Sometimes horseshoe crabs get stuck upside down, and then they simply launch themselves into a little prehistoric backflip and flip themselves upright again. 

Hell yeah.