What Makes Horseshoe Crab Blood So Special?

A horseshoe crab is a marine creature that belongs to the family Limulidae. The Horseshoe crabs are not true crabs or crustaceans, they are chelicerates, which more or less resemble arachnids like scorpions and spiders. In recent years, the blood of Horseshoe crabs has been used for health benefits. We in this article, are exploring why the blood of Horseshoe crabs is very special. Roll down!

What Are Horseshoe Crabs?

Horseshoe crabs resemble arachnids and crustaceans but are a member of the arthropod family. They prefer to live in the shallow waters along the muddy and sandy floors of the oceans. The fossils records of Horseshoe crabs show that they have been living around us for more than 480 million years.

What Is The Physical Appearance Of a Horseshoe Crab?

The body of the Horseshoe crab is enclosed in a carapace – the hard shell. They have 2 well-developed compound eyes and 2 median eyes which help them to detect both visible and ultraviolet light. Additionally, a pair of lateral eyes and single parietal eyes are located on the top of their head. They have 44 pairs of walking legs which allow them to walk on the floor of the ocean. Behind the legs, are located a pair of gills which helps them to breathe under the water.

Why The Blood Of Horseshoe Crab Blue In Colour?

The blood of the Horseshoe Crab has unique coloration, it is blue or bluish-green. The blood of Horseshoe crabs contains a copper-containing respiratory pigment called hemocyanin, which when comes in contact with air, changes color. Hemocyanin helps in the transport of oxygen to different parts of the body. Like humans, the blood doesn’t scabs or clots.

What Makes Horseshoe Crab Blood So Special?

Their blood is so unique because it provides many health benefits to humans. The blood is rich in Limulus Amebocyte Lysate (LAL), a protein that provides many health benefits to humans. Moreover, it is used used in pharmaceutical industries for the production of useful medicines and drugs.

What Are The Use Of Horseshoe Crab Blood In the Medical Industry?

The blood of Horseshoe crab has many health benefits, some of them are:

  • The protein in the blood of Horseshoe crabs helps to test the presence of endotoxins in the sample.
  • The blood can also be used in the laboratory to detect the presence of contaminating enzymes.
  • It is also useful to check the presence of bacterial substances which causes fever in humans.
  • The blood is used in the development of vaccines against measles.
  • Recently, in 2021, the vaccines for the pandemic (COVID-19) contain the blue Horseshoe crab.


The Horseshoe crab resembles scorpions and crustaceans but is not a true crab. The fossils records of Horseshoe crabs show that they have been living deep in the ocean for about 4480 million years. The uniqueness of Horseshoe crabs is that their blood contains hemocyanin which gives the blood a blue color. The bluish blood has many advantages, as it provides health benefits

About the author


I am a Scholar and a dedicated content writer. I am on a mission to stamp out the importance of one of the ocean's most fascinating and remarkable creatures, the sharks, and to let people know about their role in keeping the ecosystem in equilibrium.