Shame-faced Crab (Calappa granulata)

Finding 2 Shame-faced crabs on a dive to Mgarr-ix-Xini, was a pleasant surprise.

We spotted them on the sandy bottom, which is unusual, as they are often hidden away in the sand.

As the photo and video suggests, the female crab was in the process of shedding her old shell. During this process, the female will be held tightly by the male until the old shell is discarded and the soft, new one appears in its place. After this ritual, the pair usually bond and mate afterward

The colour of the carapace was white to rose, having 5 rows of crimson tubercles to it, and 4 rows on each forceps. The total length can reach on average 8-9 cm and a width of 11-12 cm. The carapace is dumpy in appearance, rounded and convex with 4 convergent grooves between rows of spots and flat spines around the margin. The first set of walking forceps are depressed and triangular in shape, fringed with tiny hairs which cover the eyes and hide the triangular mouth. It is believed that the hairs filter sand and other particles from water that is siphoned into the body and across the gills to extract oxygen. The line of vision is directed upwards searching for potential prey. The crab has four pairs of slim, walking legs, which are seldom used.

The Shame-faced crab is very inactive, sometimes for several days it does not move. It can be found burrowed down in the sand with just obtruding eyes, antennae and upper parts of carapace and forceps. The large forceps will form a breathing cave behind them, thus hampering any sand running in. The crab, in its resting place is well camouflaged, very difficult to spot and it rarely moves. When it moves, it runs upright, straightening its slim legs and is quite quick. To bury itself, it drops down and presses it forceps against the ground, pushing itself backwards into the substrate.

The crab feeds on molluscs and Bivalves. Its large and powerfull formed forceps are well adapted to pick snails apart and are strong enough to crack the shells.

The female lays eggs from June to September.

The Shame-faced crab is found in the Atlantic Ocean and the Mediterranean Sea: from the Sahara to the coast of Portugal and Israel in the Mediterranean.

To learn more about different marine species found in our waters, why not take the opportunity and do your PADI Fish Identification Course or your PADI Underwater Naturalist Course with us?

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