Horseshoe crabs are known as living fossils that have survived in the depths of the seas for millions of years. However, these ancient creatures are not only remarkable for their evolutionary history, but also for their blue blood. This blue blood, which has a revolutionary role in the pharmaceutical industry, has unique properties that detect and trap bacteria at the microscopic level.
Alright, blood of horseshoe crabs Why are they so valuable and how did these animals become the unsung heroes of the biomedical industry? In this article, we will explore the harvesting of horseshoe crabs’ blue blood, its importance in medical applications, and the effects of this process on the crabs.
Characteristics of Living Fossil Horseshoe Crabs
Limulidae, horseshoe crabs or horseshoe crab They are a family of animals belonging to the suborder Limulina, known as crabs, that live in marine and brackish water environments. However, since they do not belong to the crustacean phylum like real crabs, their commonly used name is incorrect and they are not crabs.
Horseshoe crabs live in and around shallow waters with soft sand or muddy bottoms and are seen in intertidal areas during spring tides. Especially in Asia. consumed as food These crabs also fish feed, fertilizer and scientific research However, in the 2000s, their population began to decline due to the destruction of coastal habitats and overfishing.
Considered to have originated 450 million years ago, horseshoe crabs living fossil According to molecular analyses conducted in 2019, horseshoe crabs are closely related to the Ricinulei family in the arachnid class.
Horseshoe crabs live on the seabed, usually near the coast. When it is time to mate, they swim in shallow waters and are hunted by predators who remove them from their habitats. These creatures have special adaptations that allow them to withstand harsh conditions such as extreme temperatures and salinity. On average, These creatures can live for 20-40 years.is in danger of extinction due to unconscious hunting.
The Blue Blood of Horseshoe Crabs
Horseshoe crabs use hemocyanin to carry oxygen in their blood, and due to the copper in hemocyanin their blood is blue. They have amebocytes in their blood to defend against pathogens. Amebocytes are the cells of vertebrates has a structure similar to white blood cells.
Amebocytes obtained from the blood of Limulus polyphemus are used to produce Limulus amebocyte lysate (LAL), which is used in medical applications to detect bacterial endotoxins. For this reason, horseshoe crabs are collected and released back into the sea after their blood is collected. Although most survive the process, mortality varies depending on the amount of blood collected and the stress experienced during transport. Estimates of mortality after blood collection range from 3-15% to 10-30%.
Blood collection, can reduce the number of eggs that female horseshoe crabs lay or prevent them from laying. According to the biomedical industry, horseshoe crabs that have been 30% bled spend one to three days out of the ocean before being returned. They can survive on land for four days as long as their gills remain moist. Some scientists suspect that some companies are not returning horseshoe crabs to the ocean and are selling them as fish bait.
The Role of Horseshoe Crabs in the Medical World
Horseshoe crabs play an important role in the medical world, especially baby blue bloodIt attracts attention with this special feature. detecting microbes thanks to its ability in testing the safety of many drugs and medical devices It is used. In addition, some substances in its shell, in the production of medicines and surgical sutures is also used.
The blue blood of horseshoe crab plays an important role in testing the sterility and toxicity of medical supplies. This blue blood is produced by only five laboratories worldwide.worth thousands of dollars per liter. The five companies that collect the crabs’ blood are: Associates of Cape Cod, Lonza, Wako Chemicals, Charles River Endosafe and Limuli Labs.
In cancer diagnosis This blood, which is also used in medicine, is of critical importance for human life. With its blue blood and unique characteristics, the horseshoe crab has formed the basis for many revolutionary discoveries in the medical world. Every year, approximately half a million horseshoe crabs are caught and bled alive.
Found in the blood of the horseshoe crab Amebocytes The cells, called coagulation factors, can detect the presence of bacteria even at microscopic levels and contain a special chemical that can trap them. Using this feature, pharmaceutical companies process blood to obtain a chemical called coagulant. Coagulant is used to detect contamination in any mixture that comes into contact with blood. If there are dangerous bacterial endotoxins in the fluid, the horseshoe crab blood extract immediately forms a clot. This clot forms a substance that scientist Fred Bang calls “gel.”
When there is no bacterial contamination, coagulation does not occur and the solution is determined to be bacteria-free. This is simple and LAL, a rapid test The (Limulus amebocyte lysate) test is used to detect possible infectious agents and has replaced the previously used longer and more expensive tests on “large rabbit colonies”. Pharmaceutical companies have abandoned rabbit tests because they find this new method both faster and more cost effective.
Horseshoe Crabs Have Been Used for Different Purposes Throughout History
The bodies of horseshoe crabs have been used for different purposes throughout history. For example, “crab manure” These animals, known as wolves, were used to enrich agricultural areas in the past. In the 20th century, they became an organized industry, especially around the Delaware Bay. Crabs steamed and ground and was used to spread over agricultural lands. The remaining animal feed were given to pigs as food. Millions of crabs were hunted for this purpose.
However, in the 1970s, as the horseshoe crab population began to decline due to human influence, the fertilizer industry declined and eventually disappeared. However, crab fishing was revived in the 1990s when fishermen realized that they could use horseshoe crabs as bait to catch large snails.
Blood Harvesting Method Does Not Harm or Kill Animals
Biomedical horseshoe crab collectors bring the crabs to the laboratory after catching them and They remove 30% of their blood by making a hole in the tissue around their heart.This blood is used to obtain a product called Limulus amebocyte lysate (LAL).
After being caught for biomedical purposes, horseshoe crabs are taken to remote areas to be released back into the sea. This process usually takes between 24-72 hours. Industry representatives claim that most of the crabs do not die during this process. However, it is estimated that 10% to 30% of the crabs that are bled may die during this process. This process can be compared to human blood donation; the crabs usually recover after receiving some nutrients.
But some researchers say that in areas heavily fished for biomedical purposes (such as Pleasant Bay in Massachusetts), They noticed that very few female crabs laid eggs.This suggests that the bleeding process of the crabs may be negatively affecting them, if not killing them.
Researchers at New Hampshire and Plymouth State Universities began testing this hypothesis by attaching accelerometers to female horseshoe crabs that were bled to see what effects the process had on the animals’ behavior and physiology. They describe their findings in a paper published in the journal The Biological Bulletin. Their research shows that the process of bleeding crabs makes them more lethargic, slower and less able to follow the current than their peers.
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