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Portunus pelagicus, also known as the blue crab, blue swimmer crab, blue manna crab and flower crab is a species of large crab found in the Indo-Pacific, including off the coasts Indonesia, [1] Malaysia, [2] Cambodia, [3] Thailand, [4] the Philippines, [5] and Vietnam; [6] and in the intertidal estuaries around most of Australia and east to New Caledonia.
The oldest known true crabs are Eoprosopon klugi and Eocarcinus praecursor from the Early to Middle Jurassic. [5] [6] While that fossil crab, and a few other Jurassic species, establish that crabs existed in older time periods, crabs did not truly diversify into numerous species until the beginning of the Cretaceous. [3]
After an analysis of new fossil material, the subgenera were elevated to the rank of genus, and three new genera were erected. [3] Most of the family's current diversity is found in temperate waters of the Northern Hemisphere .
The order is estimated to contain nearly 15,000 extant species in around 2,700 genera, with around 3,300 fossil species. [1] Nearly half of these species are crabs, with the shrimp (about 3,000 species) and Anomura including hermit crabs , king crabs , porcelain crabs , squat lobsters (about 2500 species) making up the bulk of the remainder. [ 1 ]
Dakoticancroidea is a superfamily of fossil crabs divided into the following two families: [1] [2] [3] † Dakoticancridae Rathbun, 1917 † Avitelmessus Rathbun, 1923 † Dakoticancer Rathbun, 1917 † Tetracarcinus Weller, 1905 † Ibericancridae Artal, Guinot, Van Bakel & Castillo, 2008 † Ibericancer Artal, Guinot, Van Bakel & Castillo, 2008
Fossils are rarely preserved in tropical settings in comparison to other parts of the world, making this fossil an even more unusual discovery. [7] An in-depth study of the crab's eyes indicated that Callichimaera was an active predator living high in the water column .
Coeloma is an extinct genus of crabs belonging to the family Mathildellidae. The genus includes 19 species, [ 2 ] distributed among several subgenera, and is in need of revision. [ 1 ] The fossil record of the genus extends from the Eocene to the Miocene .
In comparisons of overall morphology, M. starri was noted to be most similar to the living species M. gracils, commonly called the graceful rock crab. [1] When published, M. starri was the oldest species of Metacarcinus to be described, being older than M. coosensis, which is known from fossils found in Washington, Oregon, and California.