The Significance of the Horseshoe Crab

October 20, 2001

Biology 1321

Topic Exploration

The Significance of the Horseshoe Crab

The horseshoe crab belongs to one of the oldest living fossil groups called the Arthropoda. This bottom-dwelling organism is related to lobsters, crabs, spiders, and scorpions. Today, only four species of the horseshoe crab remain alive. Three of these species live along the coastline of Japan and Vietnam, and the fourth lives along the Atlantic Ocean. Limulus polyphemus, is the scientific name given to the Atlantic Coast horseshoe crab. It also means massive blood clotting. Did you know that the horseshoe crab plays an important role in the production of bacterial free medications? Medical and pharmaceutical companies use Limulus Amebocyte Lysate (LAL), a product produced from the blood of a horseshoe crab, to protect people from developing a deadly fever when they are injected with new drugs. Scientist, over 50 years ago, started to realize that people were developing a pyrogenic response (fever) when they were introduced to new vaccines and intravenous drugs. They soon realized that bacterial components, left over after sterilization, remained on the sterile solutions. The potent fever producing bacterial cells became known as endotoxins. Auspiciously, researchers found that solutions could be screened for endotoxins by inserting the solution into a rabbit to see if it produces a fever. If the rabbit produces a fever then they knew the solution was not sterile and would eliminate it. In addition, the shell of the horseshoe crab produces a very special component (chitin) used to facilitate burn victims, and help clean contaminated water. In the future, leukemia may be diagnosed early by another substance found in the blue- blood of the horseshoe crab.

Many researchers wonder why the horseshoe crab benefits from being sensitive to endotoxins. For example, they knew that the horseshoe crab could not develop antibodies, because it lacks an immune system. Furthermore, the researchers wondered how it maintained a healthy life because it was constantly being exposed to infection since it lives in saltwater. On the other hand, the horseshoe crab contains compounds that bind to bacteria and viruses. The final result, endtoxins help aid in wound control, but also provide additional help with a protective barrier that keeps infection out. In the early 1960’s, Dr. Frederick Bang, a Johns Hopkins researcher, discovered the LAL test (crab blood test). Bang found that when an ordinary marine bacterium was injected into the skeleton of Atlantic Horseshoe crab, massive blood clotting occurred. Massive blood clotting is called Limulus Polyphemus. Subsequently, Dr. Bang collaborated with Dr. Jack Levin and concluded that the clotting was due to an endotoxin. Furthermore, endotoxins have been known to stop the growth of cancer cells. Moreover, the researchers were able to figure out the puzzling question behind the blood clotting cells, and they came up with the answer amebocytes. The free cell reagent that resulted was called Limulus Amebocyte Lysate. Limulus is the nonspecific name given to the Horseshoe crab, and Amebocyte is the blood cell that contains the active components of the free-cell reagent. In addition, a New Jersey Sea Grant development has recently revealed an unusual protein found in the blood of the Atlantic horseshoe crab. The protein traces and attaches to the vitamin B12. This new discovery helps to detect early vitamin deficiencies, which include anemia and mental disorders in babies. Also, the shell horseshoe crab produces a very helpful substance called chitin. Chitin is a non-toxic and earth friendly material that helps assist in the removal of lead in drinking water.

Even today, the LAL blood tests are still very effective and important. The advantage of having this test is to help aid doctors in there hastily approach in diagnosing spinal meningitis, and urinary tract infections. Plus, LAL is a major instrument in the development of new vaccines and pharmaceutical drugs. For example, if doctors were not able to sterilize new drugs, we as a society would ultimately die because of our major dependency on new antibiotics and medicines for ordinary illnesses. Furthermore, without the convenience of chitin, people who have been seriously burned would not receive a faster recovery rate and people would not be drinking clean water. Many people around the world do not understand the importance of the horseshoe crab, and until they do, people will not help support the preservation practices already underway to conserve them.

While I was exploring the information on the horseshoe crab I did not realize how beneficial the horseshoe crab was to the human race. I am glad that supporters of the horseshoe crab have posted things on the Internet to help educate people on this weird looking creature. I think all of the authors have written something significant about the blue blood of the horseshoe crab. Furthermore, all of them approve and support the current research that is being done to the horseshoe crab. I definitely support their conclusions. I am glad that FDA has stepped in to protect the welfare of the horseshoe crab in the United States, because in Vietnam the population of the horseshoe crab is decreasing dramatically. In North America we have rules and regulations in place to protect the blue blood of the horseshoe crab, because is very expensive and rare. For example, scientists are only allowed to take their blue blood certain times of the year. I hope in the future, the horseshoe crab will help in the research of cancer victims.

Bibliography

Thomas J. Novitsky, Ecological Research and Development Group

PH. D. The Horseshoe Crab

http://www.horseshoecrab.org/med/med.html.

2001

Tom O’Connell. Atlantic Horseshoe Crab.

http://www.dnr.state.md.us/fisheries/education/horeseshoe/horseshoefacts.

February 26, 1999

National Aquarium In Baltimore. Horseshoe Crab Living Fossil.

http://www.aqua.org/animals/species/prhcrab.html.

1991

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