I don't know why I think this is cool, but I do...
Horseshoe Crab Blood is Gold
(Or why a living fossil may save your life)
by Chris Brunson
According to the Ecological Research & Development Group (ERDG) of Delaware, whose primary focus is the conservation of the world’s four remaining horseshoe crab species, “an extract of the horseshoe crab's blood is used by the pharmaceutical and medical device industries to ensure that their products (e.g., intravenous drugs, vaccines, and medical devices) are free of bacterial contamination. No other test works as easily or reliably for this purpose.
Horseshoe crabs aren’t bugs. They aren't really crabs, either.
The prehistoric-looking creatures known properly as Limulus polyphemus are more closely related to spiders and scorpions than true crabs. The innocuous sea creatures are living fossils and have been scuttling about quietly pretty much unchanged for some 250 million years.
So who cares? As a primate who can think, you should. The primitive immune system of the horseshoe crab makes them medically quite useful to humans. Every drug certified by the FDA must be tested using the horseshoe crab derivative known as Limulus Amebocyte Lysate (LAL).
The LAL extract made from horseshoe crab blood (which is bright blue, by the way), is used to test drugs and vaccine for possible bacterial contamination.
Horseshoe crab blood is worth an estimated $15,000 a quart, according to the Mid-Atlantic Sea Grant Programs/National Oceanic and Atmospheric Administration Web site (
www.ocean.udel.edu). Researchers have also found substances in the crabs that have potential as antibiotics as well as anti-viral and anti-cancer agents. Try to put a price on that untapped potential.
Whenever you get a vaccine, the crab’s life is linked to yours as a benefit from medical testing. That’s very good, because bad bacteria can be lethal. Gram-negative bacteria can be nasty stuff that cause life-threatening diseases like meningitis, typhoid, cholera, and toxic shock syndrome.
Some interesting things I found out about these critters...
Horseshoe Crab Facts & Figures
Despite their size and intimidating appearance, horseshoe crabs are not dangerous.
A horseshoe crab's tail, while menacing, is not a weapon. Instead, the tail is used to plow the crab through the sand and muck, to act as a rudder, and to right the crab when it accidentally tips over.
The horseshoe crab's central mouth is surrounded by its legs and while harmless, it is advisable to handle a horseshoe crab with care since you could pinch your fingers between the two parts of its shell while holding it.
Horseshoe crabs have 2 compound eyes on the top of their shells with a range of about 3 feet. The eyes are used for locating mates.
Horseshoe crabs can swim upside down in the open ocean using their dozen legs (most with claws) and a flap hiding nearly 200 flattened gills to propel themselves.
Horseshoe crabs feed mostly at night and burrow for worms and mollusks. They will, however, feed at any time.
Horseshoe crabs grow by molting and emerge 25 percent larger with each molt. After 16 molts (usually between 9 and 12 years) they will be fully grown adults.
Horseshoe crab eggs are important food for migratory shore birds that pass over the Delaware Bay during the spring mating season. Fish also eat the juveniles or recent molts.
In the 1900s, horseshoe crabs were dried for use as fertilizer and poultry food supplements before the advent of artificial fertilizers.
The medical profession uses an extract from the horseshoe crab's blue, copper-based blood called lysate to test the purity of medicines. Certain properties of the shell have also been used to speed blood clotting and to make absorbable sutures.
As for the blood...
The oxygen-carrying pigment in horseshoe brab blood is a protein called hemocyanin. It is very similar to the hemoglobinmolecule we have in our blood. Hemoglobin gets it’s red color (which makes our blood red) from the iron molecule in the center of the protein. Hemocyanin contains a copper molecule which results in a blue color.
Blood that uses a hemocyanin carrier isn’t uncommon, actually. Many arthropods and gastropods use hemocyanin. Where the horsehoe crab’s blood distinguishes itself is in its ability to detect bacterial toxins. Horseshoe crab blood clots quite quickly and visibly when in the presence of bacterial endotoxins. This ability has made horeshoe crab blood an invaluable tool in ensuring that medical drugs and equipment are sterile and bacteria free. This blue blood is the basis of an entire industry. That strange looking helmet bulldozing through the sand at the fish store is a medical marvel.
