While tidepooling in the San Francisco Area, I came across this cool creature. With a Scientific Name of Ashtoret lunaris, it is more active at night and is rarely seen in the daytime, as it is then often buried in the sediments. “Lunaris” in Latin refers to the moon.
The Spotted Moon Crab’s colors range from beige to yellow, with little maroon dots evenly sprinkled on the body surface, sometimes highlighting the six bumps. Its pincers are short, sturdy, held against the body to form a somewhat box-like shape. Its walking legs end in paddle-shaped tips and are used to skim along the sea bottom as well as being used like spades to rapidly burrow into the sand.
This crustacean is commonly encountered in sandy and muddy shores, especially near seagrass beds from the intertidal zone to a depth of 150 feet. It is usually nocturnal and spend the day buried in the substrate just below the surface, creating breathing channels to the surface of the sand.
They hunt small shellfish, worms and other animals. During the night, they are known to take other crabs. When threatened, it often draws its legs up under the overlapping edges of the carapace and appears to sham death; this may make it difficult for a predator to dismember the crab
I have caught several different types of cool crustaceans while out and about, but this was the first time I’ve ever come across this species.