Horseshoe Crabs

Horseshoe Crabs

The horseshoe crab is one of my favourite invertebrates!⁠

They're actually more similar to arachnids than crabs and they're living fossils - the oldest known species has been around for 450 million years! There's 4 species of horseshoe crab known to science today and their not dangerous - despite their appearance!⁠

The blood of a horseshoe crab is also bright blue! It contains immune cells that are exceptionally sensitive to bacteria and as a result horseshoe crab blood is used to test if vaccines are safe from contamination!⁠

Sadly horseshoe crabs are threatened by habitat loss as well as being collected for their blood (though they're returned not all of them survive). ⁠

Let me know if you've ever seen a horseshoe crab in the comments!⁠