Xiphosura - Horseshoe crab

Creature Feature – Xiphosura

This week is the letter ‘X’, and today’s featured creature is the order Xiphosura, otherwise known as horseshoe crabs!

Horseshoe crabs are older than the dinosaurs and are an incredibly important species. Did you know? They have also helped to keep most of us alive. If you have ever had a vaccine, chances are that it was tested for safety using horseshoe crab blood! Four species remain today.

Xiphosura - Horseshoe crab


Phylum: Arthropoda

Order: Xiphosura

Superfamily: Limuloidea

Family: Limulidae

Xiphosura Fact File

? Size: Females can reach lengths of up to 2ft and weigh up to 5kg, whilst males are typically 25-30% smaller

? Distribution: One species, (the Atlantic horseshoe crab) is found in North America along the Atlantic and Gulf coasts from Maine to Mexico. The other three species are found in Southeast Asia

? Diet: They are not picky eaters and consume almost anything. They feed on small clams, crustaceans, and worms; however, they will also eat other animals and even algae. Because they have no mandibles or teeth, they crush hard food between their legs before passing it to their mouth

? Behaviour: During the late spring and early summer, adult horseshoe crabs travel from deep ocean waters to beaches along the East and Gulf coasts to breed. When the females come to shore, they release natural chemicals called pheromones that attract the males and send a signal that it’s time to mate

? IUCN Status: The Tri-spine horseshoe crab is Endangered and the Atlantic horseshoe crab is vulnerable. In recent years, population declines have occurred as a consequence of coastal habitat destruction and overharvesting