Decorator Crabs Dress Their Own Shells

Some decorator crabs attach algae, sponges, and other environmental material to hooked setae on their carapace. The decoration can break up the body outline or help the crab blend into the background, reducing its visibility to predators. Behavior varies among species: some selectively use particular materials, while others use what attaches well or is locally available. A crab may replace or alter its decorations, but it is not accurate to generalize that every species always selects a new habitat-matched outfit after moulting.