The horseshoe crab's shape is ideal for bulldozing through the mud and sand, and clinging to the bottom to avoid being overturned in rough water. Its body is made up of two portions. The horseshoe got its name because its shell resembles a horse's hoof. Females larger than males. Lay their eggs on the beach, not much metamorphosis.
Hatchlings look like small adults but without tails.
Maturity in 9-12 years. Southeast Asia and the Atlantic coast. Muddy shores of river estuaries, mangroves. Horshoes are arthropods but of a separate class called merostomata and are the only members of the Order Xiphosura. There are now only 4 species of living horseshoes.