The animal with the most expensive blood in the world

The crab, also known as the horseshoe crab, is a living fossil species that lived along the coastline for 445 million years, long before dinosaurs appeared on Earth. They have the most exotic and precious blue blood of any animal alive today, according to IFL Science.

Sam’s blood plays a key role in vaccine production, helping to save millions of lives. Unlike iron-rich red blood in humans, American horseshoe crab blood (Limulus polyphemus) contains a lot of copper, creating its characteristic blue color. Instead of white blood cells, they possess cells called amebocyte that are extremely effective in detecting bacterial endotoxins. Even at doses of less than one part per trillion, amebocyte can trigger blood clotting, forming blood clots around invading bacteria to help protect the horseshoe crab’s body against toxins.

Pharmaceutical companies have used amebocyte for decades as a way to test vaccines for contamination, in a test called Limulus Amebocyte Lysate. This is a very important test because the risk of infection can be harmful, even leading to death, for vaccine users. Due to the effectiveness of the test, horseshoe crab blood costs up to 15,000 USD/liter.

However, researchers are looking for a more sustainable alternative because overharvesting is causing horseshoe crab numbers to decline. Although harvesters only take 30% of the crab’s blood before releasing it into the ocean, about 20% of the crab cannot survive. Female horseshoe crabs reproduce less after blood collection, affecting the recovery of this species.

Known as horseshoe crabs, horseshoe crabs are not members of the crustacean family but are actually related to spiders. They are members of the subphylum Pincers, which includes spiders and scorpions. Similar to those two types, horseshoe crab also molts as it grows older. Each time they molt, they crawl away from the front of their shell and leave their exoskeleton behind.