Horseshoe Crab

Lesson Plan - Get It!

Audio:

Did you guess that the critter in the beginning of the lesson is a horseshoe crab?

Nice job! Horseshoe crabs can be found deep in the ocean or on the beach. Adult horseshoe crabs stay deep in the ocean when they are feeding. When it is time to reproduce, they return to land. That is why you might spot them on the beach!

Did you know a horseshoe crab is not actually a crab? It isn't even a crustacean! Horseshoe crabs are arthropods. Insects, spiders, and scorpions are all arthropods. They have segmented bodies, jointed limbs, and a large shell that covers the body.

A horseshoe crab has fourteen legs! Just like crabs, horseshoe crabs have claws and a hard shell that covers its body. They also have a long tail. Look at the horseshoe crab's tail in the picture below.

• Do you think it looks dangerous? Why or why not? Tell a parent or teacher.

Guess what! Horseshoe crabs are harmless. Their tails may look dangerous, but they only use them for one thing. Can you guess what that is? Tell a parent or teacher.

Horseshoe crabs use their tails to flip themselves back over if they accidentally end up on their backs. If they got stuck lying on their back, an animal could come and eat them! 

Horseshoe crabs eat worms, clams, small crustaceans, and even algae! Did you know they don't have any teeth? Instead, they need to crush their food with their legs. After they have crushed their food, they can then eat it.

• Can you see their legs in the picture below?

Horseshoe crabs lay eggs. They lay their eggs up on the beach. When the eggs hatch, larvae come out. The larvae make their way to the ocean water. Here they eat and then molt their shell off for the first time. Molting is similar to how snakes shed their skin. This means they grow out of their old shell, then grow a new shell.

After they molt for the first time, they are considered to be a juvenile horseshoe crab. These small horseshoe crabs stay close to where they were born in the shallow waters of the ocean. As they grow older, they swim to deeper spots in the ocean.

Nice work! You learned about horseshoe crabs and their physical traits. Tell a parent or teacher what a horseshoe crab looks like. Then, move on to the next section.