The Carapace of a horseshoe crab has three main features, the telson, the prosoma (head) and opisthosoma (abdomen). The shell is responsible for the structure of the body.
The digestive system is pretty intense. Since the horseshoe crab is in the class of Merostomata, that means that it has its mouth in between its legs. It's also the only Merostomata to eat crustaceans and things with hard shells.
Sea Worms, Crustaceans, and Small Molluscs
Eggs: Eggs are laid on the beach. Females come first onto the beach then release a pheromone to attract males. They then lay their eggs in the 88,000’s. After that, the males and females leave the deep water once again.
Larva: When the eggs hatch, the larva. After 20 days they molt and become juvenile.
Juvenile: In this stage, they grow their tails. The then leave the nest and go to the sea. The stay close to the shore. The shell doesn't grow with the horseshoe crab, so they molt so they can grow. When they get big enough they start to make it out to deeper water.
Adult: At the adult age at 10 years they can start to reproduce. The start to come to shallower waters. After that, they can reproduce until they die.
Shallow waters, and deep reefs.