Crustacean

Thin-shelled rock crab

Grapsus tenuicrustatus

Wave-splashed rocky shores

Photo: (c) Harrison Cole, some rights reserved (CC BY) · CC-BY · Source and license. Displayed as a resized crop. Photograph illustrates the species.

Habitat: Wave-splashed rocky shores
Habitat zone: Intertidal rocks and the splash zone
Viewing activities: Beach / tidepool

What to look for

A shore crab also known as ʻaʻama in Hawaiʻi; the field account gives a shell width of about 2 inches.

Wider distribution

Hawaiʻi and the wider Indo-Pacific.

When to look

The available records do not establish a reliable local viewing season. Use the map’s month filter to inspect dated observations; it does not predict an encounter.

RECORDED PRESENCE

Where has Thin-shelled rock crab been recorded?

These destination links use the same area and date cutoff as the map: 40 km circles, except for the four named regional rectangles. Checked 2026-09-19. Counts describe source records, not individual animals or sighting odds.

HawaiʻiHawaiʻi, United StatesRegional rectangle · 3083 source records since 2016About this destination →Kona CoastHawaiʻi, United States40 km radius · 686 source records since 2016About this destination →MaldivesMaldives40 km radius · 2 source records since 2016About this destination →MauiHawaiʻi, United States40 km radius · 495 source records since 2016About this destination →OkinawaJapan40 km radius · 47 source records since 2016About this destination →Red SeaEgypt40 km radius · 10 source records since 2016About this destination →

Sources, search boundaries and limitations