Meet the Chennai Mole Crabs!
With a size not more than 35mm long, mole crabs also known as Sand crabs. They are the unseen residents of our Chennai sandy beaches that live in the swash zone. Living in this region is a challenge compared to the sheltered rocky intertidal regions. Mole crabs have a tough outer suit to deflect the force of a wave. You will never see them taking a wave with arms wide open but rather make themselves small so that they don’t get much impact from the pounding waves.
Some species have eyes on short stalks and others have eyes on long stalks. But the species found on our coast is Emerita asiatica. The home of the mole crab depends based on the tides, that it moves up or down on the beach. These crabs usually make burrows along beaches and move from one to another. Unlike most crabs that traverse the beaches from right to left, sand crabs are backwards burrowers, and when launched ashore, will furiously burrow into the sand with their rear claws until they are safely out of harm’s way. This is the sand crab’s signature movement.
Female mole crabs
Female crabs are generally much larger than the males.Females can lay up to 45,000 eggs at one time and many off-spring is needed for these guys to survive. If you think life is short think? Think of the crabs! They live only up to two to three years. During their juvenile stages, mole crabs live in a planktonic form. Adult mole crabs mainly feed on plankton which they filter from the water. Mole crabs are also great indicator species since they are used in analyzing the toxins that are present in the water.
Staying alive for these small critters is a task. Predators ranging from birds to fish. Staying in the open for too long will result in the mole crab being hunted. They are also an asset to fishermen as they are used for bait.
Mole crabs are great to watch the next time you are lounging on the beach or something for the end of your hook.
To learn more about marine critters like your Mole crabs, please do visit our Outdoor Science Field Trip page