Physical Description

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There were two Menaethius monoceros found in the reef fragment collected from Moreton Bay area with carapace length of 1.3cm (female) and 0.9cm (male) (fig. 1, top left). The carapaces were tuberculate and triangular with a dorsal elongated rostrum that had two supraorbital spines beside it. They were brown in colour with some red patches and a white heart-like badge at the middle of the carapace (fig. 1, top right). Moreover, there were some red seaweed attached on the carapace (fig. 1, top right), and the species of seaweed on their back and those the crabs were hiding in was of the same species. This behaviour is assisted by the thorn-liked structures all over its body (fig. 1, bottom left) that allow materials to attach easier. This implies that the seaweed attachedmight have camouflage function. Other than that, all paired appendages were very thin and the legs are only for walking. The female M. monoceros was also found, was carrying a batch of orange eggs (fig. 1, bottom right).

Figure 1. Top left: Two collected M.monoceros. Top right: Red Seaweed attached to the back of M. monoceros.Bottom left: Thorn-liked structure grew from the legs. Bottom right: The female M. monoceros carrying a batch of orange eggs. (Photos by Chi Chiu LO)