As Spring approaches, horseshoe crabs migrate toward shore where they will lay their eggs. Males arrive first and patrol the shallow water in search of females. During the full and new moons, when the high tide water reaches its highest levels (spring tides), the animals come ashore to lay their eggs.
When a female arrives, heading straight for the beach, a male will turn to join with her by grasping the end of her opisthosoma (the posterior-most part of her shell) with his specially-modified first pair of walking legs.
