Nature Field Guide
Mottled Shore Crab
- Spanish name
- Cangrejo costero moteado
- Scientific name
- Pachygrapsus transversus
What Do Pico & Tati Think?
Pico waits for a small movement between rocks. Tati records the difference between a hiding place and a feeding place.
Species overview
About the Mottled Shore Crab
Pachygrapsus transversus is a small shore crab that uses rocky intertidal habitat. Field observations show it using crevices for refuge and moving onto exposed rock to feed. The same shoreline can offer shelter, food and changing water conditions within a very small space.
Identification
Key Features of the Mottled Shore Crab
A small crab on rocky shore
Look for movement near existing crevices
Use a verified photograph to compare markings and body proportions
Habitat & range
Rocky shore and naturally visible tidal habitat. Choose a permitted observation point with an adult; do not turn rocks or reach into holes.
Local observations
Documented in Guanacaste. Also listed in the marine-sector crustacean inventory of Manuel Antonio National Park. Also included in the published Isla del Coco decapod checklist. Region tags represent documented locations, not an exhaustive range or a promise of occurrence at every beach. Additional regional assignments require locality evidence.
When to observe
Visibility depends on the site, conditions and the animal. Ask a local guide about an appropriate visit; no fixed encounter season is promised.
Conservation & care
Give claws and burrow entrances space. Do not handle, feed, chase or collect crabs. Leave rocks and shells where they are, and follow your adult’s route and local signs.
Observation activity
From a safe dry viewpoint, make a simple map showing a visible shelter and an open rock surface. Do not reach into the shelter.