Harvesting blood from horseshoe crabs for medical research

Written by: Lisa Stelzner

Daily Dose of Science Blog

Maybe some of you know that horseshoe crabs have blue blood (due to the presence of copper, not iron).  You may also know that their blood is very special, because it has a chemical (coagulogen) that will clot when in the presence of bacteria (the blood coagulates and turns into a gel).  This ability makes horseshoe crab blood extremely valuable to pharmaceutical companies to test if there are bacteria present in solutions.  These solutions used to be tested on rabbits, but this was a slow, expensive and inhumane process. When horseshoe crab blood was discovered in the 1950s, scientists mostly switched to using it instead for their testing, in a method called LAL, the Limulus amebocyte lysate test.

I agree very much with the author that one reason why this is so mind-blowing is because: “
I don’t know about you, but the idea that every single person in America who has ever had an injection has been protected because we harvest the blood of a forgettable sea creature with a hidden chemical superpower makes me feel a little bit crazy.”

Every FDA-certified drug must be tested by LAL. This means companies need a LOT of horseshoe crab blood.  The crab’s ecology allows them to acquire it, since they swim into very shallow water en masse to mate. Humans can collect them and drain their blood in the lab.  Only about 30% of the blood of each crab is drained, however, in hopes that the crabs will survive, can be released into the wild, and reproduce so that the medical industry isn’t the cause for their extinction, and loss of this very valuable resource (the blood can sell for $15,000 a quart).

Everything isn’t all fine and dandy for the crabs, however.  10-30% of the bled crabs die, and the ones that survive and are released are lethargic and are less likely to move to shallow waters to mate.


Photo is a screenshot from a PBS documentary called Crash

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Lisa Stelzner
I'm a plant biology PhD student studying monarch butterflies in Michigan, but I'm interested in lots of other types of science, too. I am interested in how breeding monarch butterflies choose their habitat based on floral species richness and abundance. Few studies have been conducted on optimal foraging theory when it involves an organism searching for two different kinds of resources, and butterflies are an ideal study system to investigate this, since many species are ovipositing specialists and only lay eggs on one species of hostplant, but are feeding generalists and nectar from a broad variety of flowering forbs.