| Compared with the elongate bodies of shrimps or lobsters, crabs are characterised by a compact body organisation with a depressed, short carapace and a ventrally folded pleon. The evolutionary transformation from a lobster-like crustacean towards a crab is called ‘carcinization’ and has been interpreted as a dramatic morphological change. Nevertheless, the crab-shape evolved convergently in a number of lineages within Decapoda. Accordingly, numerous hypotheses about internal and external factors have been presented, which all try to explain these frequent convergent carcinization events despite the seemingly fundamental changes in the body organisation. However, what a crab is lies greatly in the eye of the beholder and most of the hypotheses about the... |
