Sally Lightfood Crab – Grapsus adscensionis
The Sally Lightfood Crab is a species in the order of the Decapoda, and thus belongs to the subphylum of the Crustacea. Grapsus adscensionis was first described by Osbeck in 1765. Until 1990, the species was equally treated with Grapsus grapsus. However, this occurs mainly in the western Atlantic.
The Sally Lightfood Crab has a flat body that is wider than long. Young animals are black with white or beige dots. Grapsus adscensionis has with increasing age more red parts in the colouring. This applies first to the feet and the head area. Especially the joints and foremost legs seem to be affected first. Also the adult crabs have white dots, which partly merge into lines.
The body of Grapsus adscensionis reaches a maximum diameter of 74mm.
Habitat and Distribution
The Sally Lightfood Crab prefers to live on a rocky ground, in the splashing zone, above the area that the water reaches at high tide. At low tide they are also found in the tide zone.
When diving in the Canaries, it is very rare. However, anyone who undertakes a coastal walk will find it, guaranteed.
The distribution area of the Sally Lightfood Crab extends across the eastern Atlantic and the Mediterranean Sea. It is found around the Azores, Madeira, Ascension, Ilhas Selvagens, on the Atlantic coast of Morocco and around the Balearic Islands.
Grapsus adscensionis is usually found in large groups. It is active during the day, at low tide, and then dig out algae that are outside the water. At high tide and at night the Sally Lightfood Crab stays above sea level and is inactive.
Males reach their sexual maturity at about 38mm body size, while females do this with about 43mm body size.
Females produce, almost always, once between their moults, eggs. Shortly before the next moult they are hatched and shortly afterwards new ones are laid.