`A`ama (Grapsus tenuicrustatus) are frequently seen beside the ocean in Hawaii. These crabs are indigenous (arrived in Hawaii without human aid but are found in other places) and play an important role in a healthy ecosystem. Grazing on algae along the splash zones and cleaning up Hawaii's shorelines are part of its scavenger function. They are used as by humans for bait and food. Other sea creatures consume these crabs. The body shape and swift legs allow these crabs to quickly escape into rock crevices for protection. Molted red shells are left behind when abandoned for a roomier new shell. `A`ama crab movement and size remind many first time visitors to Hawaii of spiders.
Traditional Hawaiian knowledge: An olelo no`eau (Hawaiian proverb) "when the sea is rough, the 'a'ama crabs climb up on the rocks" warns one to be cautious of hazardous shoreline conditions. Offerings of `a`ama were believed to incline gods to grant favors. Whole and complete crabs were the sacred food of the kahuna (priests). `A`ama was also used to treat illness. The `ahele, a traditional long handled tool with a tight line across the V shaped end, would snare the crab's eyes or other body parts.
References for teachers: hilo.hawaii.edu/affiliates/prism/documents/Lesson5AamaandPipipi.pdf