Description
Percnon planissimum, commonly known as the flat rock crab or nimble spray crab, is a small, highly compressed, and rapid-moving crab (3-6 cm) found in tropical Indo-Pacific shallow rocky shores and coral reefs. Identified by its mottled brown/red color, bright green-blue stripes, and yellow-orange leg segments, this species inhabits shallow, turbulent waters, hiding under
Key Characteristics
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Appearance: Extremely flat, orbicular carapace (rounded) which allows them to fit into tight rocky crevices.
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Coloration: Distinctively mottled brown to reddish with bright yellow/beige longitudinal stripes, often featuring blue highlights.
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Size: Generally, the carapace width ranges from 3 to 6 cm.
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Limbs: The walking legs often have yellow-orange tips.
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Distinguishing Feature: Unlike P. gibbesi (which has banded legs), P. planissimum is recognized by yellowish streaks on the legs, though they are often confused.
Habitat and Behavior
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Location: Found in the tropical Indo-Pacific from East Africa to Japan, Hawaii, and the Philippines.
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Environment: Intertidal zone, coral reef flats, and exposed rocky shores, often found in shallow, turbulent water (0–30 meters).
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Behavior: Known for being fast-moving and shy, retreating quickly into cracks when disturbed.
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Diet: Primarily herbivorous, feeding on algae, but sometimes omnivorous, consuming small invertebrates and detritus.
P. planissimum belongs to the family Percnidae and is a common species in its native range, often seen clinging to rock walls in the intertidal zone
