Irvine Nature Center

Horseshoe Crabs at Irvine!

NOVEMBER 7 | By Guest Writer Intern Madeline Mahon

Irvine's youngsters in the Nature Preschool are currently working on raising baby horseshoe crabs right in their classroom. Though the natural habitat of horsehoe crabs is ocean waters with muddy and sandy bottoms, the animal adopts well to new settings, especially habitats as nice as Irvine’s.

The Atlantic horseshoe crab, like all other horseshoe crabs, in fact is not a crab but is closely related to scorpions and other arachnids. Though difficult to understand this looking at this creature from above, after flipping it over and viewing it from below it is quite understandable.

Parts of a Horseshoe Crab

• 1 hard shell: protects entire body
• 9 eyes: two large compound eyes and five simple eyes on the shell, and two simple eyes on underside in front of mout
• 5 pairs of legs!
• 1 long hard tail: strong enough to set them back to normal if they get flipped over. A damaged tail makes it very susceptible to predators. 
• 5 sets of ‘book’ gills: allow crabs to breathe underwater and out of water if kept moist. They also occasionally aid in swimming.

Horseshoe crabs can swim upside down at times, and feed on mollusks, worms and other small sea creatures on the sea floor.

The crabs start out very small (a female can lay as many as 120,000 eggs at once). They grow to be large, however, shedding their shells up to 17 times before full maturity at age nine. They can live from 20-40 years.