Land Hermit Crab Dukdok / Umang
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Land Hermit Crab Dukdok / Umang
Coenobita brevimanus
Native Species
Locally called "dukdok" when they are young or "umang" when they become adults, hermit crabs are so named because they hide in their shells like hermits whenever they are threatened. They are often seen in groups searching for food or new shells. There are several kinds of hermit crabs on Guam. Most live in the sea but a few live on land.
All hermit crabs are hatched from eggs laid in the sea. After spending a few weeks as tiny drifting larvae, they settle to the bottom and find a tiny empty shell to live in. Most kinds of hermit crabs spend their entire lives in the sea, but land hermit crabs crawl out onto the beach soon after finding their first shell. Once they hit the beach, they stay on land, except when the female returns to the water to lay her eggs.
After their drifting larval stage, hermit crabs spend their entire lives inside a borrowed shell which they use for protection, since their own body covering is soft and weak. When they outgrow a shell they simply find another slightly larger one and trade. The giant African snail has been a real friend to land hermit crabs since their empty shells make perfect homes.
Land hermit crabs are most abundant near the beach, but they may also be found far inland. They feed mostly at night and remain in cool shady places during the heat of the day. Finding food is not a problem for hermit crabs since they will eat almost anything including coconuts and other fallen fruits, plant material, rotting wood, dead animals, and garbage.
Guam Comprehensive Wildlife Conservation Strategy, 9/27/2005
