James Dwight DanaFRS FRSE was an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcanic activity, and the origin and structure of continents and oceans around the world.
The Decapoda or decapods are an order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and prawns. Most decapods are scavengers. The order is estimated to contain nearly 15,000 extant species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp and Anomura including hermit crabs, porcelain crabs, squat lobsters making up the bulk of the remainder. The earliest fossils of the group date to the Devonian.
The superorder Peracarida is a large group of malacostracan crustaceans, having members in marine, freshwater, and terrestrial habitats. They are chiefly defined by the presence of a brood pouch, or marsupium, formed from thin flattened plates (oostegites) borne on the basalmost segments of the legs. Peracarida is one of the largest crustacean taxa and includes about 12,000 species. Most members are less than 2 cm (0.8 in) in length, but the largest is probably the giant isopod which can reach 76 cm (30 in). The earliest known perecaridian was Oxyuropoda ligioides, a fossil of which has been found dating to the Late Devonian of Ireland.
Grapsus grapsus is one of the most common crabs along the western coast of the Americas. It is known as the red rock crab, or, along with other crabs such as Percnon gibbesi, as the Sally Lightfoot crab.
Portunidae is a family of crabs which contains the swimming crabs. Its members include many well-known shoreline crabs, such as the blue crab and velvet crab. Two genera in the family are contrastingly named Scylla and Charybdis; the former contains the economically important species black crab and Scylla paramamosain.
Tuerkayana hirtipes is a species of terrestrial crab.
Leptograpsus variegatus, known as the purple rock crab, is a marine large-eyed crab of the family Grapsidae, found in southern subtropical Indo-Pacific Oceans. It grows to around 50 millimetres (2.0 in) shell width. It is the only species in the genus Leptograpsus.
The Majoidea are a superfamily of crabs which includes the various spider crabs.
The purple shore crab is a common crab of the family Varunidae that is indigenous to the west coast of United States, Canada, and Mexico. H. nudus was first described in 1847 by Adam White, and in 1851, James Dwight Dana formally classified the species. H. nudus is a small, amphibious crab that is similar physically and behaviorally to Pachygrapsus crassipes and Hemigrapsus oregonensis. The purple shore crab is generally a dark purple color with olive green, red, and white spots. Mating season for H. nudus begins in mid-winter and larval crabs undergo 5 zoeal stages and a juvenile stage. Adult crabs mainly feed on algae but will occasionally scavenge other animals. H. nudus prefers inter-tidal and sub-tidal zones, and it can oftentimes be found sheltering under rocks or other debris. H. nudus demonstrates complex compensatory mechanisms to counteract fluctuating salinity and water oxygen concentrations, permitting it to live in a variety of different environments.
Galathea is a genus of squat lobsters in the family Galatheidae. It is one of the largest genera of squat lobsters that in 2008 contained 73 species. Most species of Galathea live in shallow waters.
Galathea intermedia is a species of squat lobster in the family Galatheidae. It is found in the north-eastern Atlantic Ocean, as far north as Troms, Norway, south to Dakar and the Mediterranean Sea.
Percnon gibbesi is a species of crab. It is one of at least two species commonly called Sally Lightfoot, and is also referred to as the nimble spray crab or urchin crab. It has been described as "the most invasive decapod species to enter the Mediterranean".
Grapsus is a genus of lightfoot crabs, comprising the following species:
Hemigrapsus is a genus of varunid crabs comprising thirteen species native almost exclusively in the Pacific Ocean, but two have been introduced to the North Atlantic region.
Oregonia is a genus of crabs, comprising two extant species and one fossil species: It is classified in the family Oregoniidae under the spider crab superfamily Majoidea.
Neohelice granulata is a species of crab in the family Varunidae, and the only species in the genus Neohelice. In 2009, it was estimated that N. granulata was the sixth most studied species of crab.
Metasesarma obesum, also known as the marble crab or marble Batik crab, is a species of sesarmid crab. It is a semiterrestrial and brackish-water crab that lives on sandy beaches.
Paragrapsus is a genus of crabs from South Eastern Australia, containing the following species:
Macrophthalmus pacificus is a species of sentinel crab found widely across the Indo-West Pacific Ocean, including India, Japan, Malaysia, New Guinea, Solomon Islands, and northern Australia.
