Flatback Mud Crab
Eurypanopeus depressus
The Flatback Mud Crab is a small, flattened native crab that hides beneath oysters, rocks, and mangrove debris in Florida estuaries.
Its low body lets it squeeze into narrow spaces in oyster reefs, salt marshes, and protected bays. It feeds on small animals and organic material while serving as prey for fish and wading birds.
Healthy oyster structure and clean estuarine water support local populations.
Habitat:
Estuaries and Bays, Mangroves and Salt Marshes, Coastal Waters
Area / Range:
Atlantic Coast, Gulf Coast, Florida Keys
Diet:
It eats worms, small mollusks, tiny crustaceans, algae, carrion, and other organic material.
Behavior:
It remains hidden under shell and debris, emerges to forage, and raises its claws defensively when exposed.
Day, Night
Active Times:
Best time to see:
At low tide beneath loose oyster shell or shoreline debris, replacing every object exactly as found.
Florida Native Status:
Native
Conservation Status:
Common in suitable estuarine habitat and not considered imperiled. Oyster loss, pollution, and shoreline hardening reduce habitat.
Safety Level:
Low Risk
Safety Information:
The small claws can pinch. Observe without handling and use gloves around sharp oyster shell.
Benefits to Property:
It recycles organic material and supports fish, birds, and other estuarine predators.
Property Concerns:
It causes no meaningful property damage and does not infest buildings.
Fun Fact:
The unusually flat body is an adaptation for living in tight crevices within oyster reefs.
Wildlife Laws:
Marine-life collection and harvest are governed by current FWC saltwater rules. Licenses, gear limits, and protected-area restrictions may apply.
Identification:
Look for a broad, noticeably flattened olive-brown shell with four side teeth behind each eye, stout unequal claws, and hairy walking legs. The fingers of the claws are dark.