Each Female Horseshoe Crab lays thousands of small greenish eggs
Horseshoe crabs arrive on the beach, usually at night on a new moon. The female crab digs holes in the beach about 6 inches in diameter and can lay as many as 100,000 eggs at one time. The male which is latched onto the female then fertilize the eggs.
Horseshoe crab eggs are a main source of food for migratory birds, most are eaten before they can even hatch.
As the embryo begins to grow it will start to resembles a trilobite. It will shed it’s shell several times in the egg before it starts to take on the shape of a Horeshoe Crab. After about 3 weeks, the embryo will have grown large enough that it is ready to hatch.
At this point it is in it’s Larvae stage. It then crawls to the surface of the sand and is picked up by the water and floats out to sea. The larvae will swim until it molts again, then it will spend the rest of it’s life on the bottom, as a horseshoe crab.
It will molt about once a year for ten years before it becomes an adult, ready to make that journey to the beach to reproduce producing more horseshoe crabs.