Good Morning Watershed Explorers,
Today's critter spotlight is about a tiny, beach creature. The mole or sand crab only reaches about 35 mm in length. Emerita talpoida can be found digging in the sand on Rhode Island beaches. My family and I found the mole crab above at Narragansett Town Beach. These critters are pretty magnificent. Female mole crabs can lay up to 45,000 eggs. These creatures are found in what is known as the swash zone. This means that they are washed up on shore with turbulent water after a wave has broken. Larva are also classified as planktonic which means that they drift with the water because they are very weak swimmers. The direction they travel and where they end up is completely dependent on water movements. Mole crabs can be found at Rhode Island beaches in the sand from early spring to late fall. Once winter comes, storms carry these little critters off to sandbars and then return them come spring.
Habitat: Emerita talpoida can be found in many parts of the Atlantic Ocean and the Gulf of Mexico. They prefer sandy beaches and dunes where they can burrow. There is also a pacific mole crab found from Alaska to California which is Emerita analoga.
Diet: Mole crabs are herbivores. They eat diatoms and dinoflagellates. These are single-celled organisms that are considered to be algae. Here are photos of diatoms and dinoflagellates.
Watershed Role: Mole crabs are a significant source of food for many marine creatures. They are fed on by otters, shore birds, sea birds, and fish. There is one problem for creatures that consume many mole crabs, however, these creatures are hosts for parasitic worms. Creatures that eat the crabs are then susceptible to damage from the worms as well. Mole crabs are often used as bait in many saltwater fishing expeditions since they are eaten by fish and don't pinch when handled.
In Friday's post, I explained that fall is a great time for a beach exploration. A mole crab sighting is one more reason to get out there an explore. Time is running out before these little creatures are carried out to sandbars for the winter.
Good luck in your explorations!