About Grapsus tenuicrustatus (Herbst, 1783)
Grapsus tenuicrustatus, also called the thin-shelled rock crab, has a deep purple to black carapace marked with many light-colored spots when it is alive. After an individual dies or sheds its shell, the empty discarded carapace changes to a bright red-orange color. This species has different common names across regions: it is called a'ama in Hawaiian, and Katang in the Philippines. Full grown thin-shelled rock crabs reach lengths of 6 to 8 centimeters, and males of this species are typically smaller than females. The wild lifespan of this species is unknown, but captive individuals have been recorded living 7 to 10 years. This crab usually lives in rocky outcrops, which provide shelter when danger approaches. Its distribution range spans the Indo-Pacific, where it inhabits beaches and tidepools along shorelines.
