Sunday, December 7, 2014

Mediterranean Shore Crab

The Mediterranean shore crab is a very common, if not the most common crab in the Maltese islands. It is a native of the Mediterranean and Black seas and parts of the Atlantic. Since 1996, probably as a result of global warming, it has also been observed in the English Channel and has been recorded as far north as Southampton.

As with many other common and widespread species, the Mediterranean shore crab has several other names such as marbled crab or the marbled rock crab. This name is a good description of the yellowish marbling pattern on its violet brown carapace.

Maltese naturalists refer to it as granċ tax-xatt to distinguish it from the many other species of crab found around the Maltese coasts but for most Maltese is just a granċ.

The Mediterranean shore crabs can be found mostly along the rocky coasts. It can be seen hunting in the open but quickly hides underneath stones or in narrow cracks in the rocks if it feels threatened. It can move in any direction and is difficult to catch with bare hands. When somebody is regressing rapidly the Maltese say sejjer lura bħal granċ meaning moving backward like a crab.

Shore crabs feeds on algae as well as small animals such as mussels and limpets and will mix their diet with both plant and animal material even if one item is very abundant.

The shore crab can disperse and colonise new areas by giving rise to large numbers of free-living larvae. These can float on the surface of the sea for several days and can travel far from their origin before finding a new place to continue developing into an adult crab.

In parts of the Maltese islands the coast is being invaded by another species of crab known as the sally lightfoot. This species is found on both sides of the Atlantic, and on the Pacific coast of North America. In 1999 it was discovered in Linosa and Sicily and in subsequent years it was also found in the Balearic Islands, in Greece, Libya and Malta. This species has been described as very invasive and can compete with the Mediterranean shore crab.

This article was published in The Times of Malta on 4 September 2014.  

No comments:

Post a Comment