rekordy: Brachyura

Evidence: 100 • authority: 72

Brachyura is an infraorder of decapod crustaceans comprising the true crabs. They typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. Their exoskeleton is often thickened and hard. They generally have five pairs of legs, and the frontmost pair end in chelae, which function as pincers. They are present in all the world's oceans, in freshwater, and on land, often hiding themselves in small crevices or burrowing into sediment. True crabs are omnivores, feeding on a variety of food, including a significant proportion of algae, as well as detritus and other invertebrates. True crabs are widely consumed by humans as food, with over 1.5 million tonne…

Evidence: 69 • authority: 72

Crabs are decapod crustaceans, either the Brachyura (the "true crabs") or various groups within the closely related Anomura (hermit crabs and allies), characterised by having a heavily armoured shell, their tail segments concealed under the body, the ability to run sideways, and the habit of hiding in rocky crevices. They do not form a single natural group or clade, but have convergently evolved multiple times from the ancestral decapod body plan through carcinisation, the process of creating this set of characteristics. As a group, they are thus polyphyletic, meaning they have multiple evolutionary origins. Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spide…

Evidence: 59 • authority: 92

Relating differential gene expression and genomic analyses to functional adaptation at various developmental stages of the blue crab, Callinectes sapidus.. Background The blue crab, Callinectes sapidus, exhibits a pelagic, planktonic larval, and benthic post-larval form before molting into a juvenile reminiscent of the adult body plan. This study examined the expression profile and genomic structure for key genes responsible for the adaptive functions involved in the blue crab at different developmental stages. The physiological behavior of each stage reflects unique life history strategies key for the successful recruitment and settlement of a species that supports one of the largest fishe…

Evidence: 49 • authority: 80

Treatise Online no. 196: Part R, Revised, Volume 1, Evolutionary history of decapod groups: Brachyura (sections Dromiacea, Homoloida, Callichimaeroida, Torynommoida, Etyoida, Raninoida, Dakoticancroida, Cyclodorippoida)

Evidence: 49 • authority: 92

Morphological diversity in true and false crabs reveals the plesiomorphy of the megalopa phase.. Brachyura and Anomala (or Anomura), also referred to as true and false crabs, form the species-rich and globally abundant group of Meiura, an ingroup of Decapoda. The evolutionary success of both groups is sometimes attributed to the process of carcinization (evolving a crab-like body), but might also be connected to the megalopa, a specific transitional larval phase. We investigate these questions, using outline analysis of the shields (carapaces) of more than 1500 meiuran crabs. We compare the morphological diversity of different developmental phases of major ingroups of true and false crabs.…

Evidence: — • authority: 72

Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Several groups such as the king crabs and porcelain crabs within the Anomura have independently undergone carcinisation, acquiring the armoured crab body plan with a concealed tail. It is the sister group to the "true crabs" or Brachyura.