Which of these crabs is in the picture?
'Pachygrapsus marmoratus' is a species of crab, sometimes called the marbled rock crab or marbled crab, which lives in the Black Sea, the Mediterranean Sea and parts of the Atlantic Ocean. It is dark violet brown, with yellow marbling, and with a body up to 36 millimetres (1.4 in) long. A semiterrestrial omnivore, it feeds on algae and various animals including mussels and limpets.
It is capable of very rapid movements, and it uses this ability to dart into crevices, making it difficult to catch