I asked Mom to tell you about Sandy, the Mole crab that Dad caught for her so she can take pictures, but first a photo of me, because Mom says I am just so adorable! 😊
Mole crabs or Emerita is a small genus of decapod crustaceans, known as mole crabs, sand crabs, sand fiddlers or sea cicada.
Mom think they are very cute and love seeing them.
Mole crabs are tiny little oval-shaped burrow animals and live in pits they dig in the wash zones along the shores of Africa, the US and Australia.
They have no claws or spines, cannot pinch or bite, and are harmless. Some people confuse Mole crabs with Sand fleas.
Mole crabs spend most of their lives in the sand in the surge zone on the beaches and get their nutrients from passing waves. Their barrel shaped body allows them to roll along with the currents.
On the underside they are able to hold the appendages close to their body, allowing them to absorb heavy impacts from waves. They have five sets of legs which only allow them to move backwards.
They also have a special V shaped digging tool that is known as a ‘telson’, which is attached to the back of the body and it faces forwards. This provides protection for the soft underbelly when it is in the folded position. The telson is also used to anchor them into the sand.
Mole crabs can move backwards and dig themselves into wet sand by using the telson and they can do that very fast. It can bury itself completely in just 1.5 seconds, to be safe from predators.
The females are larger than the males and can be 4cm long when fully grown.
The mole crab’s eyes are attached to eye “stalks,” which reach above the sand, as do their two pair of antennae. The first pair of antennae are used for respiration and the second set, which are feather-shaped, are used to scoop up and filter microscopic phytoplankton.
They use their feathery antennae by extending it into the water and then they filter plankton and detritus from the water as it washes past them.
Once they have a limit of tasty phytoplankton, they retract the antennae and pull them into their mouths and scrape off their lunch.
Since sand crabs live in sand—the area of the ocean most often contaminated by toxins—they play an important role in the beach ecosystem. Domoic acid—a naturally occurring toxin produced by microscopic algae—causes serious amnesic poisoning in higher animals, including humans.
Filter feeders, like mole crabs, ingest the toxin, and it progresses up the food chain. The amount of domoic acid in the crabs’ flesh can indicate the amount of toxin in the water.
Laboratories use sand crabs in neurological studies because the crabs’ tails have the largest sensory neurons found in any animal.
They have a short lifespan of around 2 to 3 years and can reproduce in the first year. Mating occurs mostly in spring and summer. The female mole crabs, like Sandy can produce up to 45,000 eggs per month.
The eggs stay attached to the underside of the mother and take about a full month to develop.
The eggs start off with a bright orange color and as they near hatching, they become dark brown. When they hatch, the larvae emerge and live as plankton before morphing into adults and joining a colony on the beach.
Dad opened Sandy’s underside carefully so Mom can take photos of the eggs. I can’t believe those are tiny, little mole crabs!
Mole crabs are a popular food for seabirds, shorebirds and fish. For certain fish, these crabs make up the majority of their diet.
Because of this, fishermen and fisheries often use them as bait. Dad doesn’t use them for bait. He makes his own. Dad also put Sandy back into the sea after Mom took the photos. 🙂
Because they are easy prey for birds, mole crabs are more active at night.
Not like me. I sleep at night. I like my sleep. Sometimes I sleep with Mom and Dad on the bed and other times I like to sleep in my own bed.
I think I am going to take a nap before I swallow all of you. 😛
Thanks for reading and enjoy your day. 🙂
Lots of licks and love