Why Do Horseshoe Crabs Live in the Intertidal Zone?
Horseshoe crabs (Limulus polyphemus) are shallow water dwellers. Their favored habitat is determined by temperature, salinity and tolerance to high turbidity. These factors are prime in the intertidal zone.RangeHorseshoe crabs are found along the east coast of the United States from Florida to Maine. The majority live in shallow water in the intertidal zone.TemperatureHorseshoe crabs prefer warmer ocean temperatures. Since surface waters are warmer, they live in shallower waters. They prefer 65 to 80 degrees F. In northern waters particularly, these temperatures only occur in estuaries and intertidal zones.SalinityHorseshoe crabs are tolerant of relatively wide ranges in salinity, making it possible for them to survive and thrive in areas that exclude other species. Adults prefer salinities between 20 and 30 parts per thousand–well below average open-ocean salinity of around 35 parts per thousand. The preferred salinities are often found in intertidal zones and estuaries.TurbidityInte
