Cyclograpsus Integer

A small, fast shore crab that hugs the splash zone of boulder fields, cobble bars, and seawalls in Dominica. It tucks under flat stones just above the high-tide line and along quiet creek mouths, using narrow crevices and driftwood for cover. Reliable places include rocky points around Scotts Head, mixed rock–sand pockets near Cabrits Marine Reserve, and the stony margins at the Indian River mouth where bay water meets river flow. After rainfall, individuals spread onto damp rock faces to graze before retreating with the rising tide.

Ecology and identification

Compact and nearly round in outline (carapace typically 15–25 mm across), Cyclograpsus integer shows low, smooth sculpting, short, sturdy claws, and long walking legs that grip wet stone. Colors range gray-brown to slate with subtle flecking; juveniles are paler. It grazes biofilm, diatoms and filamentous algae, scrapes microscopic invertebrates from rock, and scavenges wind-blown detritus caught in cracks. By cleaning surfaces and shredding trapped leaf litter, it supports shoreline ecosystems, adds to coastal biodiversity, and feeds into the diets of herons and small predatory fishes within everyday wildlife. Females brood eggs under the abdomen; larvae develop in the plankton offshore before megalopa settle back to rocky edges on Dominican coasts.

Sightings and best viewing areas

Twilight at low tide is best. Scan the upper splash zone for quick lateral dashes between stones, then look on the wave-sheltered side of boulders. Around Scotts Head, watch surge channels as sets subside; at Cabrits Marine Reserve, check the boundary where algae-coated rock meets sand. At the Indian River mouth, follow the line of scattered rip-rap above the waterline. If you lift a stone, replace it exactly as found so the intertidal micro-habitat remains intact for crabs and other shore life.