Callinectes Marginatus

The Callinectes Marginatus is a paddle-legged swimming Crab of quiet coasts, that favours sandy and muddy bottoms along bays, mangrove creeks, and seagrass edges. Around Portsmouth, it turns up in calm water near the mouth of the Indian River, inside Prince Rupert Bay, and along gently sloping beaches where fine sediment collects. Museum and checklist records list the species for Dominica, placing it among Dominican crabs that also appear across the Lesser Antilles.

Ecology and Identification

The carapace bears nine lateral spines on each side, with the last spine conspicuously longer than the one before it. Adults typically reach about 10 cm in carapace width. Hind legs are flattened like oars for swimming, and coloration runs olive to gray-brown with marbling and bluish tints on the claws. Juveniles shelter among mangrove roots and thin seagrass; adults range across open flats and channel mouths.

An opportunistic predator and scavenger, it feeds on small bivalves, polychaete worms, crustaceans, carrion, and occasional small fishes, linking shallow-water food webs from mangroves to nearshore grass beds. Precopulatory courtship is typical of portunids; in tropical waters, ovigerous females are reported in most months, with studies showing peaks in the dry season in comparable Caribbean settings.

Sightings and Best Viewing Areas

Dusk and calm nights are productive. In shin-deep water along the inner fringe of Prince Rupert Bay or at the Indian River mouth, watch for quick sideways sprints followed by a shallow dig that leaves only the eyes exposed. On clear mornings, snorkels over thin grass beds reveal crabs cruising just above the bottom. Landings at the Portsmouth Fisheries Complex sometimes include specimens, offering close looks that complement field observations.