Bigger is Better
Ever wonder why you find so many dead crabs on the beach during the summer? Most of these “dead crabs” are actually crab molts. A molt is an exact copy of a crab, complete with gill coverings, without the actual animal in it! In order to grow, crabs have to shed their hard outer shell, also known as their exoskeleton. When a crab is ready to molt, it backs out of its shell through a split at the back edge of its carapace (the large flat surface on its back). This molting reveals the crab’s new soft shell, which fills with water to make the shell bigger than the old one. The crab then spends the next year growing to fill the shell.
Viewer Tip: The next time you head to the beach, pay attention to how many crab shells you see. A simple way to tell the difference between a dead crab and a molt is to smell it. If it smells like a dead crab, then it is one. However, if it smells like the ocean, it’s a molt. If you don’t want to risk smelling it, simply try lifting the back edge of the shell. If it’s a molt, the back of the shell will be detached from body and you’ll be able to look inside!
Season: Summer
This information is provided by the Port Townsend Marine Science Center. Learn more at www.ptmsc.org.
(Sources: Oregon Department of Fish and Wildlife, http://www.dfw.state.or.us/MRP/shellfish/crab/Lifehistory.asp; Washington Department of Fish and Wildlife, http://wdfw.wa.gov/fish/shelfish/crabreg/crabbio.htm)
