Specimen Showcase | The Blue-blooded Horseshoe Crab

We sometimes use “the blue blood” to describe nobility. Do you know that the blue blood really exists in nature? In horseshoe crabs!

American Horseshoe Crab (side view)

The blood of horseshoe crabs is white originally but will turn blue when in contact with air. The blue comes from hemocyanin which is a copper-based oxygen-carrying molecule. Horseshoe crabs are the true blue blood! 👍🏻

American Horseshoe Crab (bottom view)

They are also an ancient group that still look similar to their fossil relatives, even after millions of years. Thus, they are also called the “living fossils”; although this term is actually not accurate as horseshoe crabs still experienced evolutionary changes over time even if their overall morphology presents resemblance with their long extinct ancestors.

Close-up of the legs and other body parts of American Horseshoe Crab

Only four horseshoe crab species are found around the world today, with two of them occurring in Hong Kong. You can find juveniles on mudflats at low tides, and sometimes adults during breeding seasons, but avoid disturbing them😉.

We have specimens of 3 horseshoe crab species in the museum. Do have a look at them when you visit us!😉

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