How horseshoe crabs save lives

Every time you get a flu shot, you should thank a horseshoe crab. Most medical interventions—vaccines, drugs, devices—have been tested on horseshoe crabs. Their blood clots immediately when it's exposed to dangerous bacteria. The biomedical industry bleeds horseshoe crabs routinely in order to make sure their products won't poison patients. But horseshoe crabs are in decline, and an NC company is trying to figure out how to raise them sustainably.

Meet the horseshoe crab, a creature that’s been around for 400 millions years. And here’s Rachel Kulberg, Ph.D, the scientist who’s trying to figure out a way to raise them.

" If you can see that hole there, that’s their mouth and it’s surrounded by these teeth-like bristles, and they don't have teeth so what they do is they is grab onto the food and walk with it and grind it and ingest it that way" said Kulberg.

We're standing in a backyard garden, where Kulberg hopes to raise horseshoe crabs.

"So this is CAARE, a backyard aquaponic farm in the heart of Durham, NC," said Kulberg. "It’s kind of a perfect animal to integrate into this system because it could be a high profit margin as well as an animal we should think about conserving."

Horseshoe crabs are big money to the biomedical industry. Every time you get a flu shot, you should probably thank a horseshoe crab. Basically any medical device or drug that goes into your body, (think vaccines, pacemakers, hip replacements) has been tested using the blood of horseshoe crabs.

The copper in their blood gives it that bright blue color, but that isn’t the only thing that’s special about it. Horseshoe crab blood clots almost immediately when it’s exposed to dangerous bacteria or fungi. It’s part of the reason horseshoe crabs have outlasted the dinosaurs. It’s also the reason the biomedical industry depends on them to make sure their products won’t cause infections.

Anthony Dellinger, research scientist at Kepley Biosystems explains. "Fishing participants will go out and collect the crabs and put them in a boat. They’ll transport them in a truck back to the facility. Then they’ll bend the crab in such a way to have access to the membrane. They’ll stick a syringe in that membrane and let the blood drain out."

"A horseshoe crab that’s maybe twice the size of this one to the industry is worth about $1,800," said Kulberg. "You get really attached to these creatures, which I don’t understand because how could you get attached to a creature that looks like that. They don’t get a cookie or orange juice like we do when we give blood, so what happens to these creatures after they’re put back in the wild, nobody knows, they’re not tagged."

Bleeding horseshoe crabs doesn’t kill them, and companies only take 30 percent of the crab’s blood. In exchange, millions of lives are saved from diseases like sepsis. However, according to research from Kepley Biosystems, in some areas of the US the combination of bleeding, over-harvesting and habitat destruction has caused a 95 percent decline of spawning horseshoe crabs.

So horseshoe crabs are stressed out. "We’ve only really been harvesting them for the biomedical industry for a short snap second in their lifetime," said Dellinger. "We want to offer a new way to collect horseshoe crabs, whereby you’re not pulling them from the wild, but you’re actually maintaining them in a managed closed loop system, a trackable one so we know which horseshoe crab is being bleed."

It’s difficult to keep horseshoe crabs alive longer than six months, and Kulberg says she thinks it’s because of their diet. So she and her team from Kepley Biosystems are experimenting with different types of food. Rachel says her dream is to eventually spread their knowledge of raising horseshoe crabs to farmers.

"We can potentially set up contract farmers with to integrate them into their farming systems because God knowns farmers could use more income," she said.

But for now, since horseshoe crabs have saved millions of lives, we thought it was only right to give them some treats.

 - Rossie Izlar

Rossie Izlar is the associate producer on the UNC-TV Science team.