Crustaceans, Pacific Northwest
The slender decorator Crab is quite abundant here on the BC coast, you can see them crawling all over the bottom at low tide and they are just fascinating to observe as they go about the business of being crabs. The Decorator Crab is the more spider like than any of the other spider crabs. This crab has pincers on its front legs specifically designed to add bits of stuff to its shell, the shell itself has sharp spines that the crab uses to hold down bits of debris that help it hide. The crab is heart shaped, it is from tan to red under all the camouflage. They completely decorate their carapace and legs with bits of seaweed, algae, sponges, and all kinds of other bits until they look like walking plants, absolutely fascinating.
They can be found from Alaska to California with very large populations on the BC coast. You can see them from low tide mark to depths of 500 meters. It ranges from North Alaska to Central California.
Slender Decorator Crabs eat plankton, but will also eat the flesh of dead animals. They in turn, are a favorite food of the halibut, other fish, sea lions, seals and otters.
The spawning season is usually between May and August. Males reach maturity after their last molt, which is when they are about 10 cm across the shell, females reach maturity when they become about 9 cm across.
The Slender Decorator Crabs are one of several spider crabs that can be found on the BC coast, they are incredible to see. You will most likely need to watch the bottom for awhile, until you see a plant begin to move across the bottom, look harder and you will see that plant is really a crab.