In Asia, they are also harmed by pollution, rising sea levels and building work. Its large hard shell serves as microhabitat for many other species such as sponges, mud crabs, mussels and snails.'īut living alongside humans can be difficult for horseshoe crabs. One of their ecological functions is to lay millions of eggs on beaches to feed shorebirds, fish and other wildlife. The International Union for the Conservation of Nature (IUCN) says, 'The horseshoe crab is a critical link to coastal biodiversity. They are also good for fishermen because they help keep the sediment around coastlines healthy. These crabs may look prehistoric, but they do an important job of supporting other animals around them: their eggs are a nourishing snack for migrating birds. The fourth is the American horseshoe crab ( Limulus polyphemus ) which lives along the east coast of North America, with a particularly large number going to the beaches of the Delaware Bay to mate each year.
