Fauna
Invertebrate

Mottled Shore Crab

Pachygrapsus transversus

Also known as Transverse Shore Crab, Mottled Sally Lightfoot

Mottled shore crabs scuttle along intertidal rocks and mangrove roots, gripping slick surfaces firmly with hooked dactyli even under crashing waves. They spend low tides grazing algae from stone with quick, alternating scoops of their spoon-tipped pincers while scavenging organic scraps. Highly vigilant, they immediately vanish into tight crevices or dive into tide pools at the slightest overhead shadow.

IntertidalCrustaceanOmnivorous
Mottled Shore Crab reference1 / 6
(c) Thomaz de Carvalho Callado, some rights reserved (CC BY) · cc-by
—observations
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyGreen algae, Red algae, Small invertebrates
Predators
  • Herons
  • Gulls
  • Octopuses
ThreatsCoastal development, shoreline armoring, oil spills, and water pollution
HabitatsRocky intertidal zones, jetties, tide pools, and mangrove roots
Life span2–3 years
Classification
  1. FamilyGrapsidae
  2. SpeciesPachygrapsus transversus
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Safe to observe at a normal distance.
Responsible observation
  • Tide Pool Etiquette: Step carefully across algae-covered rocks and leave sheltering stones unturned to preserve their microhabitats.
  • Observation Timing: Watch rocky jetties during falling tides when individuals emerge from water to scrape algae from stone.
Related species
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