Horseshoe crab blood is highly valued, especially in the biomedical field. Its blue blood is essential in ensuring safe and sterile vaccines and medical equipment.[1][2][3][4]
In this article, we’ll delve into the science behind horseshoe crab blood, exploring not only why it’s blue but also its unique properties and how these make it indispensable in medicine. We’ll also touch upon the ecological and economic impacts and the ongoing search for alternatives. Importantly, we will talk about Factor C, a promising new alternative that may stop the process of horseshoe crab blood harvesting altogether!
Before we move on to that and to some sad facts regarding the mortality of horseshoe crabs that do have their blood drained, let’s look at the fun-to-discuss fact of how much horseshoe crab blood is worth.
A 2008 NPR article said the value of horseshoe crab blood was $15,000 a liter, and even today, this figure is given as a common answer. In reality, it seems that the exact value is hard to verify and would also logically fluctuate based on current demand and other conditions. With that in mind, it is generally agreed that horseshoe crab blood is among the most expensive natural resources utilized in the medical industry.[5]
Let’s move on now to what makes it valuable and unique.
Horseshoe crab blood is famous for its bright sky-blue color, a characteristic due to the presence of hemocyanin. Hemocyanin, containing copper, performs a similar function in horseshoe crabs as hemoglobin, which contains iron, does in human blood. While hemoglobin gives human blood its red color, hemocyanin is responsible for the blue color of horseshoe crab blood.[6][7]
Additionally, vertebrates like humans carry white blood cells in their bloodstreams, whereas invertebrates like horseshoe crabs have amebocytes. In horseshoe crabs, these amebocytes contain a special protein called Limulus Amebocyte Lysate (LAL), which has significant coagulative effects and is particularly useful in medical applications.[8]
The medical significance of horseshoe crab blood lies in its unique biological properties, primarily due to LAL. This component is crucial in the pharmaceutical industry for detecting bacterial endotoxins, which can be harmful. LAL tests are standard in ensuring that medical equipment and pharmaceutical products, such as intravenous drugs and vaccines, are free of these dangerous bacteria.[9][10]
During the COVID-19 pandemic, the importance of LAL was highlighted, bringing even more attention to the horseshoe crab. This is because LAL played a key role in testing the safety and efficacy of COVID-19 vaccines, ensuring they were free from bacterial contamination before public approval. This test is also employed to confirm the sterility of medical devices and surgical tools, guaranteeing their safety for use in medical procedures.
The indispensable nature of horseshoe crab blood in these critical areas, along with the related costs of extracting the blood safely (which we will discuss below), is a large part of what gives it its value. With that in mind, let’s move on to exploring the important ecological impact and why it’s so important to find a viable permanent alternative.
FACT: Annually, the pharmaceutical industry performs approximately 70 million endotoxin tests, underlining the extensive use and demand for horseshoe crab blood. This demand has fostered a multimillion-dollar industry encompassing the collection, processing, and supply of this resource.
The harvesting of horseshoe crab blood for biomedical use has significant ecological implications. This is true not only for the horseshoe crabs but for the broader marine ecosystem.
The process of harvesting horseshoe crab blood, often involving the collection and bleeding of live crabs, has raised concerns about its sustainability. While crabs are typically returned to the ocean after bleeding, the process can be harmful and sometimes lethal. This practice has contributed to a decline in horseshoe crab populations in some areas.
Horseshoe crabs are a keystone species in their ecosystems. They play a critical role in the food chain, particularly for migratory shorebirds that feed on horseshoe crab eggs. The reduction in horseshoe crab populations due to blood harvesting and other factors can, therefore, have cascading effects on these birds and other marine life that depend on them.[11]
In response to these concerns, regulations have been implemented to improve the traceability and record-keeping of horseshoe crab harvests. However, these regulations have not significantly limited the harvesting of horseshoe crab blood, leaving the long-term ecological impact a matter of ongoing concern and study.
Mortality and Decline in Horseshoe Crab Populations Due to Blood Harvesting: The harvesting process of horseshoe crab blood for biomedical uses involves collecting and bleeding the animals before releasing them back into the sea. Although most of the animals survive this process, mortality rates following blood harvesting vary from 3–15% to as high as 10–30%. It is also estimated that between 450,000 – 700,000 a year are taken from beaches during spawning season. The mortality rate is often cited as 15%, and the number taken as half a million. This harvesting practice, coupled with the stress experienced during handling and transportation, has led to a decline in horseshoe crab populations, particularly on the East Coast of the United States.[12][13]
The conservation status of horseshoe crabs has been a growing concern, especially in light of their increased harvesting for medical purposes. In the 1990s, a significant rise in the harvest of these ancient creatures for both biomedical use and as bait in conch and American eel fisheries prompted the need for coast-wide management. To address this, the Atlantic States Marine Fisheries Commission developed a management plan in 1998. This plan, alongside its subsequent addenda, established mandatory state-by-state harvest quotas and led to the creation of the Carl N. Shuster Jr. Horseshoe Crab Sanctuary off the coast of Delaware Bay. These measures, along with innovative bait conservation techniques, have been instrumental in reducing commercial landings of horseshoe crabs in recent years, demonstrating a proactive approach to conserving this vital species.[14]
Horseshoe Crabs, the Living Fossil: According to information found on Wikipedia, The fossil record of Xiphosura, the group to which horseshoe crabs belong, dates back over 440 million years to the Ordovician period. The oldest representatives of the modern family Limulidae, to which current horseshoe crabs belong, are estimated to be about 250 million years old, dating back to the Early Triassic period. These extant forms of horseshoe crabs have been described as “living fossils,” indicating their ancient lineage and minimal evolutionary change over millions of years.
The development of synthetic alternatives to horseshoe crab blood, such as recombinant Factor C (rFC), marks a significant advancement in the biomedical field. This innovation offers a sustainable option for endotoxin detection, potentially reducing the reliance on horseshoe crab blood.[15]
First commercialized in 2003, rFC provides a more sustainable method for endotoxin detection, potentially reducing dependence on horseshoe crab blood. Research has shown that rFC assays are comparable to traditional LAL-based methods in detecting endotoxins, offering similar efficacy.
Despite its benefits, the adoption of rFC in some organizations has been slow due to concerns about its newness or perceived lack of equivalency to LAL tests. However, rFC has been well-established for almost two decades, and numerous peer-reviewed studies have confirmed its reliability and effectiveness.
Perhaps even more importantly, it has shown its effectiveness in practice. In 2018, Eli Lilly’s Emgality, a migraine drug, became the first FDA-approved drug tested using rFC, marking a significant milestone in its acceptance. Since then, regulatory bodies around the world have approved many other drugs tested with rFC, and it is now used by hundreds of organizations in over thirty countries.[16]
Other factors slowing down mass adoption include its status in some regions, such as the US and Japan, as a “non-pharmacopeial assay”. In simple terms, this means it hasn’t been officially adopted in standard-setting publications. While this doesn’t stop its use, it does stand as one of the things preventing the transition to rFC.
To aid in the transition to rFC, vendors offer solutions to streamline the validation process, including full validation protocols and advanced software that supports multiple BET methods, including rFC. This support makes it easier for laboratories to adopt rFC assays, enhancing their efficiency and sustainability. Embracing rFC as an alternative to horseshoe crab blood could be a critical step in balancing medical needs with ecological conservation.
All this to say, rFC is a viable and increasingly adopted alternative to horseshoe crab blood for endotoxin detection. However, the complete replacement of horseshoe crab blood in the industry depends on further regulatory acceptance and the willingness of more organizations to transition to this sustainable alternative.
There is no doubt about the value of horseshoe crab blood. But exploring this topic exposes bigger issues such as a decline in horseshoe crab populations affects not only the crabs themselves but also the broader marine ecosystem.
The development of synthetic alternatives like recombinant Factor C (rFC) offers hope that one day we can talk about the value of Factor C and not the sustainability of an ancient species.
Thomas DeMichele is the content creator behind ObamaCareFacts.com, FactMyth.com, CryptocurrencyFacts.com, and other DogMediaSolutions.com and Massive Dog properties. He also contributes to MakerDAO and other cryptocurrency-based projects. Tom's focus in all...
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