Living Legends
Horeshoe crab (Limulus polyphemus)
Horseshoe crab shells are frequently found washed up on Capers Island and other beaches. To know if it is a true molt or shed of its exoskeleton is sometime difficult to determine. If it looks like the shell is peeling open around the upper edge, it is probably a molt. If the shell is stinky and some arms, gills, and mouth can be seen, it is probably a dead horseshoe crab.
These invertebrates are living legends. They are nicknamed living fossils because they have been on this planet for 450 million years. And they haven’t changed! One reason their kind has survived for such a long time is due to their incredible immune system. We are going to try to summarize and simplify scientists’ discovery of horseshoe crab’s immune system and will include links to more detailed articles below!
Scientists learned:
1) Horseshoe crabs contain blue blood due to the copper in their blood. ( we have iron in our blood therefore it is red).
2) In their blood there are special “hemocytes” aka protective baddie blood cells.
3) The hemocytes are able to find unwanted bacteria and other organisms invading the horseshoe crab.
4) These cells then clot and help destroy the unwanted toxins in the horseshoe crab’s body!!! (in the most simplest explanation please click on this link for a VERY detailed explanation).
Because of this incredible immune system, humans actually use the compound Limulus Amebocyte Lysate, aka LAL, which is derived from horseshoe crab blood to test medical equipment and vaccines to make sure they are sterile. There is a synthetic version of this compound that was created in the 90’s called Recombinant Factor C, or rFC.
Due to its population decline, biologists are pushing for humans to use the synthetic version of this compound. Horseshoe crabs are declining due to habitat loss, over harvesting for bait usage or bleeding, pollution, and other factors. Invertebrates lack some fundamental protections that charismatic megafauna often receive. Because horseshoe crabs play a vital role in the ecological food chain, have been around for a long time, and are important to humans they and other invertebrates should have better protections!
Check out these links for more information on horseshoe crabs and their amazing immune systems: