Crash: A Tale of Two Species
The Benefits of Blue Blood

Horseshoe crab blood

It fuels the journeys of shorebirds along the Eastern Seaboard and feeds some loggerhead sea turtles and sharks. The horseshoe crab is intricately woven into the web of life. Yet this harmless and primitive sea creature not only plays a key role in nature, it occupies a crucial place in the human world as well.

Over three decades ago, medicine claimed this ancient animal as a new life-saving tool. In 1971 researchers discovered that when they exposed the horseshoe crab to E. coli bacteria, the crab’s blood clotted. The clotting indicated the presence of endotoxins, toxic substances released by E. coli and other gram-negative bacteria that could produce severe symptoms in exposed humans such as fever or hemorrhagic stroke.

The simplicity of its immune system is actually what makes the crab’s blood useful to our biomedical industry. Horseshoe crabs live under the constant threat of infection in a habitat that can easily contain billions of bacteria per milliliter. To fight off infection, the horseshoe crab has a compound in its blood — LAL, or Limulus Amebocyte Lysate — which immediately binds and clots around fungi, viruses, and bacterial endotoxins.

LAL’s endotoxin binding and clotting ability is what makes it so invaluable to our own pharmaceutical industry. Once the LAL test was recognized by the Food and Drug Administration (FDA) as an alternative to then current methods of testing for endotoxins, the pharmaceutical industry tapped in. Horseshoe crabs were abundant, their blood easy to harvest and the test took only one hour.

Today, LAL has become the worldwide standard screening test for bacterial contamination. Every drug certified by the FDA must be tested using LAL, as do surgical implants such as pacemakers and prosthetic devices.

Horseshoe crab blood has not only become a key weapon in our medical arsenal, it has also become big business. On the world market, a quart of horseshoe crab blood has a price tag of an estimated $15,000, leading to overall revenues from the LAL industry estimated at U.S. $50 million per year. But that pales in comparison to its value to the pharmaceutical industry.

Of course, to obtain LAL you need horseshoe crabs — and lots of them. According to the Atlantic States Marine Fisheries Commission, that $50 million dollar industry requires the blood of approximately 250,000 horseshoe crabs.

While the blood of a horseshoe crab can be extracted without killing the animal, there is some question of how harmful bleeding is to the animals. The LAL industry says the bleeding causes no long-term injury.

Adult horseshoe crabs are collected by trawlers and transported to the LAL lab, where they are washed to remove sand and other marine debris from their exoskeletons. Those crabs without visible injuries are placed on a rack and bled with a large-gauge needle. Up to 30% of the crab’s blood is removed. Within 72 hours, the bled horseshoe crabs are returned to the water, where their blood volume rebounds in about a week.

LAL manufacturers have measured mortality rates of less then 3%. Yet two recent studies estimate that between 10% and 15% of crabs do not survive the bleeding procedure, which accounts for the mortality of 20,000 to 37,500 horseshoe crabs per year. Another concern is that it takes the crab a few months to rebuild its blood cell count level back up after a bleeding. Horseshoe crabs could be bled up to three or four times a year, which would take a toll on the health of the animals. But LAL manufacturers claim they only bleed them once a year.

Whether we can or will protect the health of horseshoe crabs for their own benefit, for the good of other creatures, or for our own use remains to be seen. Despite supporting the fishing industry for over 100 years, the condition of horseshoe crab populations has largely been ignored by fishery managers until recently. With growing concern over declining populations, regulations on the harvest of Horseshoe Crabs have just recently been imposed, though some states are already loosening restrictions.

Perhaps science can step in and “give back” to the animal for all of the good it has done us. Researchers are focusing their attention on producing LAL without the horseshoe crab, exploring the potential to cultivate and produce LAL from other sources.

  • Itena

    I like this site, it is very informative.

  • usman b abdul ali

    we are joint this business horseshoe crab blood
    so many in my island in sabah malaysia please i joint
    to become suplyer this blood. i no comment.

  • madola

    this crab you can get too many!in east coast of asia,if you really need the blue blood for supply, why not you make another partner here,don’t say $15,000..per quart, if you want it,you just give us your technologies and we do the works here and supply it for you..!$10,000per quart enough for us..! how about that? if this thing real,is it good offer.?

  • Roberto

    It would be good to get a crab blood supply from elsewhere, but that is not the most important point. We are destroying global ecological networks. The horseshoe, with its valuable blue blood, is also depended upon for its eggs — as food for migrating birds and other species. Sure, Malaysia should sell the blood, but that won’t help the migrating bird species in this hemisphere.

  • Helia

    I get out of scientist, researchers and profiteers that say it doesn’t hurt the animal, as if they can ask the animal that question. While it holds true that scientist and researchers are making huge progress in the conservation of life, how many species must die or be eradicated before realizing that the human race cannot survive without them.

  • Nina Miller

    When is this show going to be aired again?

  • NATURE Online

    To find out when “Crash” will air again in your local area, click the “schedule” link at the top of the site.

  • Will B

    Why don’t they rehab the crabs while they build their blood back up so they can sell the crabs that die to the eel fishers. Love PBS and thanks to all who make it possible.

  • anon 001

    Perhaps the blood harvesting companies should consider feeding the horseshoe crabs before releasing them back into the wild(to help replenish their strength). At $15,000 a quart you would think a bit of feed isn’t too much to ask. Think of it like the courtesy snacks we get for donating blood. Free cookie anyone?

  • Bonnie Towles

    I was appalled at the harsh, indifferent handling of the crabs and at the cost charged for their blood. Typical of big pharmaceutical companies … It is unfortunate that the video mentioned the cost since now every yahoo will be catching and trying to bleed the creatures. As for their decline, perhaps it has something to do with bleeding them … It would be nice to have a link to info re: how the process was developed and how much and how often blood can be drawn. Also, on research to create a synthetic replacement. The ban on catching them for bait should be permanent. So few fisherman destroy so many crabs just to catch eels that they should be helped to segue into a different means of making a living …

  • kuala88

    singapore has success fully find out the enzymes that use to detect medicine . if this can be use for the replacement, horse shoe crabs will be saved.

  • GO Crabs!

    All the comments about not hurting the crabs are awesome but how do you suppose we continue to test all of these medical devices and drugs for endotoxin without the crabs blood. Until we find another way to make the lysate without crab blood those crabs are saving human lives! If these devices were released before they were tested for endotoxin and they were dirty it would cause a horrible fever and possibly shock or death to the patient. Not to mention that if the patient is having a medical device used on them or they are taking a drug their immune is probably already compromised and they do not need any more stress from the endotoxin being introduced into their bodies. SOOO until an alternative is found I say GO Crabs!

  • Em

    Actually, there IS an in-vitro pyrogen test that has proven to match (and even surpass) the LAL in accuracy, precision, cost, and speed. Five methods of endotoxin testing have already been validated in Europe, and if pharmaceutical and medical device testing companies would just contribute to helping validate the methods in the US as well, we would have more human-relevant information that could TRULY save human lives. There are alternatives. We just need to get the industry to support in-vitro testing instead of the outdated and less-accurate animal tests that are easier for them to continue doing.

  • Tony McGuane

    I think that it is interesting that the crabs have blue blood in the first place lol! But truthfuly it was kind of boring.

  • michaelpDHS

    I agree that blue blood is pretty cool but there really is no sure way on how to track how many die which could help the population.



  • Cynthiaaa

    Itss weird how the crabs blood is worth so much $ .. !

  • Dariusz

    If Limulus ever extinct the all of animals of earth will die.
    Because Limulus were feed and kept all of ecosystems in earth since since since,since How many years??

  • Crabula

    Why cant they be farmed instead of released and a blanket ban on wild horseshoe crab fishing be created? The image above is quite perturbing though. As someone who works in biotechnology research with this blood i can say that the amount of blood its possible to save using these creatures will far outweigh that which is taken, and that doesn’t just include humans. What if the technology or methods discovered using horseshoe crab blood led to the end of a disease that would otherwise kill millions of horseshoe crabs? Just a thought :)

  • Ben

    There are no publications yet as to the artificial production of Limulus Amebocyte Lysate. However, microbial production of LAL is a focus of my research. Keep in mind all you environmentalists that this feat will require the genetic engineering of a new host species, as ‘organic’ Limulus Amebocyte Lysate cannot be produced outside of 4 horseshoe crab species. So you can’t win them all.

  • Lynn K Stimeling

    Ben and Em – do you have links to current studies and other info? I’m a Green Eggs and Sand grad but am finding information for those with a casual interest in HSC hard to dig up.

  • Debra

    After reading what others have said here, its important for all to understand why they dont do more for the crab. It cost money. Right now, it does not cost them to feed this crab. They have people catch them and release them and those crab go off and eat on there own. To feed them, cage them, and clean after them, it would double the price for what their blood cost now. As for using something else instead of the crab, they were using rabbits. Rabbits are easy to reproduce but still cost to feed, cage and clean after them. Most people dont want rabbits used in tests. This can also be a costly issue if people take you to court to stop the use of rabbits. Since no one said much about the crab it was a cheap way and a better way to save money. I am not sure if they tag the crab to make sure they are not bleeding the same one to soon, or to find out how many die, but it would be a easy method but again it costs money. So we hope that we can find a alternative but here comes what I keep saying ….it costs big money. But there is hope. The show did have other methods they were working on for the fisherman that catch eel. But the biggest issue is to save the crab for endless reasons besides their blood and birds and sharks. They save people. Millions of people. So now we need to support these people that are trying to save them. This could be one of the biggests harmful things, if they die off! It would be like all the bee’s dieing. Think of what that would do.

  • Peter Louie

    Has there been a study done on the amount of bleeding from the crabs and theri survival rate afterwards? Instead of taking 30% of its blood; perhaps 10 or 15% of bleeding may reduce their motality rate down from the 15 to 20% down to 5% or lower!

  • phil

    What is not well explained here is that there are literally thousands of strains of E.coli bacteria, and nearly all of them are completely harmless to human beings. They live inside us and on us all the time. There are a few strains that are dangerous, among them E.coli 0157, which is commonly found in the faecal matter of factory farmed animals. this seems to be a very archaic method of detecting contamination which could surely be eradicated using High temperature autoclaving or similar. This sounds like a cheaper alternative to me, and as the crab protest rate is very small, everyone is happy(?)

  • kannan

    Good info i need more information on this business.I’m from malaysia.

  • Robotics

    Very strange subject.. thanks for sharing!!

  • brandon

    I found this artical to be very informative. I think i may start catching crabs and join in on the purse. Any information would be great. Like how to get started, draining techineques and who to sell the blood to. I am eager to get started next spring. Maybe they will have a pbs special about me.

  • Jack

    Why not use a genetic approach to transform E.coli with required components to use the E.coli or any other system as bioengineers of LAL?

  • James

    I feel horrible for these creatures, people think they can just take from any resource…

  • Kyle

    It occurs to me that to guarantee that crabs aren’t harvested more than once a year, all that need be done is to mark their shells with some type of paint/marker that deteriated after aprox a year (so long as harvesters could be kept honest).

  • Laura

    As a microbiologist who has been using horseshoe crab products to perform testing of medical devices and drugs for nearly 15 years, I wanted to address some of the concerns/questions posted here.

    - Crab mortality: The previous test, which is still used some, used rabbits. The rabbits always died in the end. The vast majority of the crabs survive and are even seen by the LAL manufacturers year after year. Horseshoe crabs are in more danger from loss of habitat as their environments are being destroyed, than from the dangers of the lab.

    - Frequency of bleeding: The major US manufacturers collect the crabs once a year during several very busy weeks, I belive in the spring. They clean and tag the crabs. If one comes in that already has a tag, they can see when/where it was last bled. They do see “repeat donors” from previous years.

    - “Why not take less blood from them?”: They will actually stop bleeding on their own before reaching a critical blood loss. Each crab determines how much blood it “donates”. Very few crabs die during the process and they have a full year to recover.

    - “I’ll catch some and bleed them in my basement for that much money!”: NO! For one, I doubt any of the people posting that have any training in handling horseshoe crabs. Also, the blood has to be taken in a very, very clean or sterile environment to ensure that the blood is not contaminated. Plus, it’s not just a matter of getting the blood from the horsehoe crab, the blood goes through additional processing.

    - Alternative methods: There is definitely research going on trying to find alternate methods. So far, the man-made versions being developed don’t work as well as the real stuff and can not be used at all with a lot of products that must be tested. Also, it takes a lot of research and testing to have a new test method approved for use. Unfortunately it’s usually a pretty slow process. Someone asked about autoclaving everything because “E. coli is easy to kill”. Well, there are a lot of Gram-negative bacteria other than E. coli and yes, most of them are rather easy to kill. The problem is that the endotoxin is still there, even if the bacteria are dead. The only way to remove endotoxin is with very high-temperature heat. Many drugs and medical devices (especially anything made of plastic) can not handle temperatures high enough to destroy the endotoxin.

    I am sure that eventually we will have a synthetic substitute to the component in horseshoe crab blood. In the mean time, these wonderful, prehistoric animals (they are older than the dinosaurs!) are saving potentially millions of lives a year. They definitely deserve our respect and continued efforts to protect them and their environment.

  • Rick

    I have a house on Nantucket Sound where there are hundreds of dead horseshoe crabs on the beach. Can the carcass of a recently dead horseshoe crab on the beach be transported in a timely manner to the processing facility, which is not far away, to process the blood?

  • zana

    i work on horseshoe crab ecology in the east coast of Peninsular Malaysia…I call for total protection of this harmless creature!!!

  • Jay

    Thanks for the info Laura. As a wildlife biologist/micro biologist I often find myself riding the fence on these matters. My instincts are rooted in conservation and because of that, stories like these make me cringe. However pragmatism asserts the value of these practices. Interesting read. Zana, I sincerely wish you luck in your endeavor.

  • Mimi

    Mankind is so unbelievably greedy! We think this planet and it’s creatures are here for us to use, destroy,and exploit. There is also the fact that humans are reactive as a rule not proactive so we won’t take action to conserve or protect until things are dire. Add to all this that big business rules! They do as they please and screw the planet.

    We are clearly destroying this beautiful planet as well as ourselves all for the almighty dollar.
    I could just puke thinking about it.

  • Joyce

    I tell everyone i see now, the story of the Horseshoe Crab, also I ad as long as their is a need by the “company, this creature of life for other life will be saved. the question is full protection, or will they go back to be hunted..
    as the many creatures used in the “best interest of lives… it is such a twisted decision all of the time. I just loved
    the fact a picture of these creatures donating (did they sign a clawmark), they never dared show a rabbit,dog,cat,turtle,bird,monkey, or in their greatness a gorilla… i guess we will see how this goes with the “company, it should only be 3 to 5 years before they are no longer “donating..

    ps that picture is right out of a scarey movie or ufo book, just think people on that line

  • Jo O’Keefe

    Laura, Thank you for your responses. In one sentence you said that you do not repeat bleed crabs that you can tell have already been bled. In another you say that they have a year to recover — seeming to indicate that you will bleed them again.

    What percentage are female? They are bled when they are spawning. They come ashore by the thousands to spawn and, while on the beach, are scooped up by fishermen and taken to a lab.

    Is there a way to prevent bleeding an egg-filled female?

  • Matt

    Mimi, make sure when you are dying of sepsis from an infection, to tell the doctors not to use any medication on you, or surgery for that matter, as medical tools are tested using LAL. Infact, don’t use any medication, household products, etc, because then you might just be deemed a ‘hypocrite’.. hmm.. but of course *you’re* not destroying the planet, right? You must live in a mud hut and eat food you harvest yourself. How on earth are you commenting on here if you are so worthy and ideal? How selfish, as you say..

  • Robert

    I have the financial means to build a big enough lab to grow and bleed these crabs which would be farming. I would not have to hurt the ones in the wild.
    Is that legal ?
    And who would i contact for the specs for the process and selling of the blood ?

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