Crustaceans, Pacific Northwest
The Mud Flat crabs can be found throughout the Pacific Northwest coastal region, including all of Vancouver Island. When approached this tiny crustacean will rear up on its hind legs, ready to do battle.
At low tide, the Mud Flat Crabs can be found wandering about the island’s mud flats searching for bits of plants or animals to eat. When threatened it will often run to the nearest rock and hide underneath, but if caught it will put up quite a fight with its strong pincers.
Breeding happens in the late spring to early summer, the female crab carries its eggs attached to the underside of its tail using specially designed legs. The babies hatch into the water at high tide and drift off as a member of the plankton. After spending weeks floating about they settle to the bottom where they begin their life.
Great blue herons and crows capture many an unwary crab and even the occasional raccoon will hunt for these delicious creatures as the tide recedes. In rocky areas of Vancouver Island, you will find a close cousin of the mudflat crab called the purple shore crab.
Because mudflat crabs are enclosed in a shell that does not grow, it must molt. This molting takes place about seven times during the first year of life and at a decelerating rate thereafter. An average size of 4 cm across the back is reached at one year of age.
Old crab shells may wash in on beaches in large numbers and become the basis for false reports of dead crabs.
If a young crab loses a limb, it can regrow it quite quickly as they molt quite often, but older crabs could take years to regrow limbs as they molt less often.