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Today on Animal Fact Files we’re discussing Dungeness crabs. With a name like Dungeness there has to be some meaning behind it, right? While it might inspire images of goblins and dragons in underground mazes, the name has a less fantastical origin. It has to do with somewhere these crabs live: Dungeness Spit. These crabs range from the cold coastal shores of Alaska down to the warm bays of southern California and northern Mexico, and, depending on where they live, their development changes. Dungeness crabs living in the northern part of their range take longer to develop than their warm water living relatives. They also reproduce later in the year.

Dungeness crabs molt their outer shell once per year. The process takes about two months from start to finish with the new shell hardening over the course of about eight weeks. It's around this time that males and females mate. The ladies store sperm for more than two years, and their egg bunches can be fertilized by more than one male. Considering they have around two million eggs each season, it's not surprising things can get mixed and mingled. Heck, cats only have like a dozen kittens at most and even they can have different fathers in a single litter!

Dungeness crab eggs start out bright orange. Like coconut crabs, the female broods her eggs on her body, carrying them on her abdomen for about three months. As they develop, they turn brown. During this time, the clutch can become infected by parasites like nematodes who can reduce the size of the clutch by up to half! The eggs that make it, however, will hatch as planktonic larvae that undergo multiple stages before becoming juveniles that settle on the seafloor. Juvenile Dungeness crabs live in shallow water habitats like estuaries and prefer eelgrass and bivalve shell beds. They use these areas to hide from predators while they develop over their first two years of life. After this, they move out to the open ocean to join the adults.

Adult Dungeness crabs live on soft sediment from intertidal areas to just over 750 (230m) feet below the waves. They spend their days buried in the substrate. They may do this to hide from predators, prey, or even conserve energy. Some Dungeness crabs spend more than two days buried in the sand! At night, during high tide, they hunt. These arthropods are known to be voracious eaters and consume anything from fish to shrimp to each other if the opportunity arises. Actually, juvenile Dungeness crabs specifically have to watch out for each other while they develop to avoid becoming their neighbor's dinner! Other predators to these invertebrates include sea otters, as well as fish like wolf eels and salmon. Humans eat Dungeness crabs, too. In fact, they make up a huge commercial market along the United States West coast, though only males are allowed to be kept after capture.

Males and females can be told apart by their abdomen. Females are round while males are triangular in shape. The crabs can reach up to ten inches (25cm) across their back, but most only reach a little over half this. They have a smooth shell, four pairs of walking legs, and a set of pincers which they use to hold prey while they tear it apart. Compared to other crabs that inhabit similar areas, such as king crabs, Dungeness crabs have shorter legs.

These decapods can live to be about ten years old, though most males are caught by the time they're about half this age as that is approximately when they reach legal size for keeping. 

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