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Guides
Portunus sayi
Sargassum Swimming Crab
Portunus sayi is a pelagic swimming crab endemic to floating Sargassum seaweed mats in the western Atlantic Ocean and Caribbean Sea. It exhibits specialized adaptations for swimming, including paddle-shaped fourth legs that enable rapid sideways movement. The species relies on chemical, visual, and tactile cues to locate and select host Sargassum patches, demonstrating strong host fidelity. Recent records from the Amazon continental shelf represent the northernmost observation in Brazilian waters, expanding its known range.