Rust-Spotted Guard Crab

Trapezia rufopunctata

The Rust-spotted Guard Crab, Trapezia rufopunctata, is a true crab species known for its mutualistic relationship with corals. It can reach a width of 5 cm and is characterized by a trapezoidal shell with 100 to 200 reddish or orange spots set against a white or pink backdrop. This coloration aids in its camouflage among the corals it inhabits. Its eyes are a vivid green, contrasting with its body. The crab's large, flattened claws serve both defensive and feeding purposes. When faced with threats, it quickly retreats into the safety of coral branches, holding its claws up defensively. This species is distributed throughout the Indo-Pacific region, including notable locations like the Great Barrier Reef and Bali. It prefers coastal reef environments and lagoons, inhabiting depths from 0 to 30 meters in warm waters with temperatures between 20 and 36 °C. Trapezia rufopunctata primarily resides on hard corals, especially those belonging to the Stylophora and Pocillopora genera. The Rust-spotted Guard Crab feeds on coral polyps and mucus, playing a vital role in defending corals from predators such as the crown-of-thorns starfish. It also aids in cleaning corals of detrimental vermetid snail mucus. Reproduction involves a courtship ritual, and the female carries fertilized eggs until they hatch into planktonic larvae. This species has not been evaluated for conservation status, but it is favored in aquariums for its beneficial role in coral health.