‘Living fossil’: the blue-blood arthropod that has changed little in 445m years

Published 11 August 2026 · health

Tenacious and confounding, the horseshoe crab pre-dates dinosaurs and has copper-based blood vital to vaccine safety They pre-date dinosaurs, eat food using their legs and

Tenacious and confounding, the horseshoe crab pre-dates dinosaurs and has copper-based blood vital to vaccine safety They pre-date dinosaurs, eat food using their legs and contain blue blood that we use to keep us healthy. Horseshoe crabs are the supreme, if offbeat, survivors of the invertebrate world.

Often called “living fossils” for visually obvious reasons – horseshoe crabs resemble a sort of prehistoric helmet (their Japanese name translates as “helmet crab”) – these animals have barely changed appearance along a lineage that stretches back 445m years.

It’s invertebrate of the year again! From 3-12 August, every day we will profile one of the thousands of amazing invertebrates that our readers have nominated. And then, when you’ve heard about all of them, we’ll open the voting so you can choose your favourites.

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