Fauna
Invertebrate

Marbled Crab

Pachygrapsus marmoratus

Also known as Marbled Rock Crab, Runner Crab

Marbled crabs scramble agilely across sunlit intertidal rocks, using stiff bristles on their legs to grip slippery surfaces even in crashing surf. Capable of spending extended periods out of water, they retreat into deep cracks or plunge into tidepools at the slightest vibration or threat. Their strong pincers easily crack open mussels and scrape tough algae, playing an active role in shaping rocky shoreline ecosystems.

CrustaceanIntertidalScavenger
Marbled Crab reference1 / 6
(c) Duarte Frade, some rights reserved (CC BY) · cc-by
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyMediterranean Mussel, Common Limpet, Intertidal Algae
Predators
  • Gulls
  • Common Octopus
  • Predatory fish
ThreatsCoastal development, marine oil spills, and water pollution
HabitatsRocky intertidal zones, exposed shorelines, jetties, and breakwaters
Life span3–5 years
Classification
  1. FamilyGrapsidae
  2. SpeciesPachygrapsus marmoratus
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
Pincers can deliver a sharp pinch if grabbed; observe without handling.
Responsible observation
  • Explore tide pools: Look along rocky crevices and stone breakwaters at low tide.
  • Move slowly: Fast movement or casting shadows causes them to dart into cracks.
  • Avoid handling: Keep hands clear to prevent a painful pinch from their claws.
Related species
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