Echinoderm is the common name given to any member of the phylum Echinodermata of marine animals. The adults are recognizable by their radial symmetry, include such well-known animals as sea stars, sea urchins, sand dollars, sea cucumbers, as well as the sea lilies or "stone lilies". Echinoderms are found from the intertidal zone to the abyssal zone; the phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest phylum that has no freshwater or terrestrial representatives. Aside from the hard-to-classify Arkarua, the first definitive members of the phylum appeared near the start of the Cambrian. One group of Cambrian echinoderms, the cinctans, which are close to the base of the echinoderm origin, have been found to possess external gills used for filter feeding, similar to those possessed by chordates and hemichordates; the echinoderms are important both geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans.
Most echinoderms are able to reproduce asexually and regenerate tissue and limbs. Geologically, the value of echinoderms is in their ossified skeletons, which are major contributors to many limestone formations, can provide valuable clues as to the geological environment, they were the most used species in regenerative research in the 20th centuries. Further, it is held by some scientists that the radiation of echinoderms was responsible for the Mesozoic Marine Revolution. Along with the chordates and hemichordates, echinoderms are deuterostomes, one of the two major divisions of the bilaterians, the other being the protostomes. During the early development of the embryo, in deuterostomes, the blastopore becomes the anus whereas in the protostomes, it becomes the mouth. In deuterostomes, the mouth develops at a stage, at the opposite end of the blastula from the blastopore, a gut forms connecting the two; the larvae of echinoderms have bilateral symmetry but this is lost during metamorphosis when their bodies are reorganised and develop the characteristic radial symmetry of the echinoderm pentamerism.
The characteristics of adult echinoderms are the possession of a water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles connected by a mesh of collagen fibres. A 2014 analysis of 219 genes from all classes of echinoderms gives the following phylogenetic tree. There are a total of about 7,000 extant species of echinoderm as well as about 13,000 extinct species, they are found in habitats ranging from shallow intertidal areas to abyssal depths. Two main subdivisions are traditionally recognised: the more familiar motile Eleutherozoa, which encompasses the Asteroidea, Ophiuroidea and Holothuroidea; these consist of the extinct blastoids and Paracrinoids. A fifth class of Eleutherozoa consisting of just three species, the Concentricycloidea, were merged into the Asteroidea; the fossil record includes a large number of other classes which do not appear to fall into any extant crown group. All echinoderms are marine and nearly all are benthic; the oldest known echinoderm fossil may be Arkarua from the Precambrian of Australia.
It is a disc-like fossil with radial ridges on the rim and a five-pointed central depression marked with radial lines. However, no stereom or internal structure showing a water vascular system is present and the identification is inconclusive; the first universally accepted echinoderms appear in the Lower Cambrian period, asterozoans appeared in the Ordovician and the crinoids were a dominant group in the Paleozoic. Echinoderms left behind an extensive fossil record, it is hypothesised that the ancestor of all echinoderms was a simple, bilaterally symmetrical animal with a mouth and anus. This ancestral stock adopted an attached mode of life and suspension feeding, developed radial symmetry as this was more advantageous for such an existence; the larvae of all echinoderms are now bilaterally symmetrical and all develop radial symmetry at metamorphosis. The starfish and crinoids still attach themselves to the seabed while changing to their adult form; the first echinoderms gave rise to free-moving groups.
The evolution of endoskeletal plates with stereom structure and of external ciliary grooves for feeding were early echinoderm developments. The Paleozoic echinoderms were globular, attached to the substrate and were orientated with their oral surfaces upwards; the fossil echinoderms had ambulacral grooves extending down the side of the body, fringed on either side by brachioles, structures similar to the pinnules of a modern crinoid. It seems probable that the mouth-upward orientation is the primitive state and that at some stage, all the classes of echinoderms except the crinoids reversed this to become mouth-downward. Before this happened, the podia had a feeding function as they do in the crinoids today, their locomotor function came after the re-orientation of the mouth when the podia were in contact with the substrate for the firs
Sea urchins or urchins are spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres, their tests are round and spiny from 3 to 10 cm across. Sea urchins move crawling with their tube feet, sometimes pushing themselves with their spines, they feed on algae but eat slow-moving or sessile animals. Their predators include sea otters, wolf eels, triggerfish. Like other echinoderms, urchins have fivefold symmetry as adults, but their pluteus larvae have bilateral symmetry, indicating that they belong to the Bilateria, the large group of animal phyla that includes chordates, arthropods and molluscs, they are distributed across all the oceans, all climates from tropical to polar, inhabit marine benthic habitats from rocky shores to hadal zone depths. Echinoids have a rich fossil record dating back to the Ordovician, some 450 million years ago, their closest relatives among the echinoderms are the sea cucumbers.
The animals have been studied since the 19th century as model organisms in developmental biology, as their embryos were easy to observe. Species such as the slate pencil urchin are popular in aquariums, where they are useful for controlling algae. Fossil urchins have been used as protective amulets. Sea urchins are members of the phylum Echinodermata, which includes sea stars, sea cucumbers, brittle stars, crinoids. Like other echinoderms, they have five-fold symmetry and move by means of hundreds of tiny, adhesive "tube feet"; the symmetry is not obvious in the living animal, but is visible in the dried test. The term "sea urchin" refers to the "regular echinoids", which are symmetrical and globular, includes several different taxonomic groups, with two subclasses: Euechinoidea and Cidaroidea or "slate-pencil urchins", which have thick, blunt spines, with algae and sponges growing on them; the "irregular" sea urchins are an infra-class inside the Euechinoidea, called Irregularia, include Atelostomata and Neognathostomata.
Irregular echinoids include: flattened sand dollars, sea biscuits, heart urchins. Together with sea cucumbers, they make up the subphylum Echinozoa, characterized by a globoid shape without arms or projecting rays. Sea cucumbers and the irregular echinoids have secondarily evolved diverse shapes. Although many sea cucumbers have branched tentacles surrounding their oral openings, these have originated from modified tube feet and are not homologous to the arms of the crinoids, sea stars, brittle stars. Urchins range in size from 3 to 10 cm, although the largest species can reach up to 36 cm, they have a rigid spherical body bearing moveable spines, which gives the class the name Echinoidea. The name "urchin" is an old word for hedgehog; the name is derived from Latin ericius, hedgehog. Like other echinoderms, sea urchin early larvae have bilateral symmetry, but they develop five-fold symmetry as they mature; this is most apparent in the "regular" sea urchins, which have spherical bodies with five sized parts radiating out from their central axes.
The mouth is at the anus at the top. Several sea urchins, including the sand dollars, are oval in shape, with distinct front and rear ends, giving them a degree of bilateral symmetry. In these urchins, the upper surface of the body is domed, but the underside is flat, while the sides are devoid of tube feet; this "irregular" body form has evolved to allow the animals to burrow through sand or other soft materials. Sea urchins may appear to be incapable of moving. Sometimes the most visible sign of life is the spines, which are attached to ball-and-socket joints and can point in any direction. Sea urchins have no visible eyes, legs, or means of propulsion, but can move but over hard surfaces using adhesive tube feet, working in conjunction with the spines; the internal organs are enclosed in a hard shell or test composed of fused plates of calcium carbonate covered by a thin dermis and epidermis. The test is rigid, divides into five ambulacral grooves separated by five interambulacral areas; each of these areas consists of two rows of plates, so the sea urchin test includes 20 rows of plates in total.
The plates are covered in rounded tubercles which contain the sockets to which the spines are attached by ball and socket joints. The inner surface of the test is lined by peritoneum. Sea urchins convert aqueous carbon dioxide using a catalytic process involving nickel into the calcium carbonate portion of the test. Most species have two series of spines and secondary, distributed over the surface of the body, with the shortest at the poles and the longest at the equator; the spines are hollow and cylindrical. Contraction of the muscular sheath that covers the test causes the spines to lean in one direction or another, while an inner sheath of collagen fibres can reversibly change from soft to rigid which can lock the spine i
Great Barrier Reef
The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres over an area of 344,400 square kilometres. The reef is located off the coast of Queensland, Australia; the Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is built by billions of tiny organisms, known as coral polyps, it supports a wide diversity of life and was selected as a World Heritage Site in 1981. CNN labelled it one of the seven natural wonders of the world; the Queensland National Trust named it a state icon of Queensland. A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as fishing and tourism. Other environmental pressures on the reef and its ecosystem include runoff, climate change accompanied by mass coral bleaching, dumping of dredging sludge and cyclic population outbreaks of the crown-of-thorns starfish.
According to a study published in October 2012 by the Proceedings of the National Academy of Sciences, the reef has lost more than half its coral cover since 1985. The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander peoples, is an important part of local groups' cultures and spirituality; the reef is a popular destination for tourists in the Whitsunday Islands and Cairns regions. Tourism is an important economic activity for the region, generating over AUD$3 billion per year. In November 2014, Google launched Google Underwater Street View in 3D of the Great Barrier Reef. A March 2016 report stated that coral bleaching was more widespread than thought affecting the northern parts of the reef as a result of warming ocean temperatures. In October 2016, Outside published an obituary for the reef. In March 2017, the journal Nature published a paper showing that huge sections of an 800-kilometre stretch in the northern part of the reef had died in the course of 2016 due to high water temperatures, an event that the authors put down to the effects of global climate change.
The Great Barrier Reef is a distinct feature of the East Australian Cordillera division. It reaches from Torres Strait in the north to the unnamed passage between Lady Elliot Island and Fraser Island in the south. Lady Elliot Island is located 1,915 km southeast of Bramble Cay, it includes the smaller Murray Islands. The plate tectonic theory indicates Australia has moved northwards at a rate of 7 cm per year, starting during the Cenozoic. Eastern Australia experienced a period of tectonic uplift, which moved the drainage divide in Queensland 400 km inland. During this time, Queensland experienced volcanic eruptions leading to central and shield volcanoes and basalt flows; some of these became high islands. After the Coral Sea Basin formed, coral reefs began to grow in the Basin, but until about 25 million years ago, northern Queensland was still in temperate waters south of the tropics—too cool to support coral growth; the Great Barrier Reef's development history is complex. Reefs can increase in diameter by 1 to 3 centimetres per year, grow vertically anywhere from 1 to 25 cm per year.
When Queensland edged into tropical waters 24 million years ago, some coral grew, but a sedimentation regime developed with erosion of the Great Dividing Range. 10 million years ago, the sea level lowered, which further enabled sedimentation. The reef's substrate may have needed to build up from the sediment until its edge was too far away for suspended sediments to inhibit coral growth. In addition 400,000 years ago there was a warm interglacial period with higher sea levels and a 4 °C water temperature change; the land that formed the substrate of the current Great Barrier Reef was a coastal plain formed from the eroded sediments of the Great Dividing Range with some larger hills. The Reef Research Centre, a Cooperative Research Centre, has found coral'skeleton' deposits that date back half a million years; the Great Barrier Reef Marine Park Authority considers the earliest evidence of complete reef structures to have been 600,000 years ago. According to the GBRMPA, the current, living reef structure is believed to have begun growing on the older platform about 20,000 years ago.
The Australian Institute of Marine Science agrees, placing the beginning of the growth of the current reef at the time of the Last Glacial Maximum. At around that time, sea level was 120 metres lower. From 20,000 years ago until 6,000 years ago, sea level rose around the world; as it rose, the corals could grow higher on the newly submerged maritime margins of the hills of the coastal plain. By around 13,000 years ago the sea level was only 60 metres lower than the present day, corals began to surround the hills of the coastal plain, which were, by continental islands; as the sea level rose further still, most of
Microalgae or microphytes are microscopic algae found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individually, or in groups. Depending on the species, their sizes can range from a few micrometers to a few hundred micrometers. Unlike higher plants, microalgae stems, or leaves, they are specially adapted to an environment dominated by viscous forces. Microalgae, capable of performing photosynthesis, are important for life on earth. Microalgae, together with bacteria, form the base of the food web and provide energy for all the trophic levels above them. Microalgae biomass is measured with chlorophyll a concentrations and can provide a useful index of potential production; the standing stock of microphytes is related to that of its predators. Without grazing pressures the standing stock of microphytes decreases; the biodiversity of microalgae is enormous and they represent an untapped resource. It has been estimated that about 200,000-800,000 species in many different genera exist of which about 50,000 species are described.
Over 15,000 novel compounds originating from algal biomass have been chemically determined. Most of these microalgae species produce unique products like carotenoids, fatty acids, polymers, peptides and sterols; the chemical composition of microalgae is not an intrinsic constant factor but varies over a wide range, both depending on species and on cultivation conditions. Some microalgae have the capacity to acclimate to changes in environmental conditions by altering their chemical composition in response to environmental variability. A dramatic example is their ability to replace phospholipids with non-phosphorus membrane lipids in P-depleted environments, it is possible to accumulate the desired products in microalgae to a large extent by changing environmental factors, like temperature, illumination, pH, CO2 supply and nutrients. Microphytes produce chemical signals which contribute to prey selection and avoidance; these chemical signals affect large scale tropic structures such as algal blooms but propagate by simple diffusion and laminar advective flow.
Microalgae such as microphytes constitute the basic foodstuff for numerous aquaculture species filtering bivalves. Photosynthetic and chemosynthetic microbes can form symbiotic relationships with host organisms, they provide them with vitamins and polyunsaturated fatty acids, necessary for the growth of the bivalves which are unable to synthesize it themselves. In addition, because the cells grow in aqueous suspension, they have more efficient access to water, CO2, other nutrients. Microalgae play a major role in nutrient fixing inorganic carbon into organic molecules. While fish oil has become famous for its omega-3 fatty acid content, fish don't produce omega-3s, instead accumulating their omega-3 reserves by consuming microalgae; these omega-3 fatty acids can be obtained in the human diet directly from the microalgae that produce them. A range of microalgae species are produced in hatcheries and are used in a variety of ways for commercial purposes. Studies have estimated the main factors in the success of a microalgae hatchery system to be.
NOAA, DMS and Climate Microalgae concentrates Microalgae research "From Micro-Algae to Blue Oil", ParisTech Review, Dec. 2011CompanyMicrophyt - Microalgae Production and Photobioreactor Design
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans and bodies of fresh water; the word zooplankton is derived from the Greek zoon, meaning "animal", planktos, meaning "wanderer" or "drifter". Individual zooplankton are microscopic, but some are larger and visible to the naked eye. Zooplankton is a categorization spanning a range of organism sizes including small protozoans and large metazoans, it includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile, benthic existence. Although zooplankton are transported by ambient water currents, many have locomotion, used to avoid predators or to increase prey encounter rate. Ecologically important protozoan zooplankton groups include the foraminiferans and dinoflagellates. Important metazoan zooplankton include cnidarians such as the Portuguese Man o' War; this wide phylogenetic range includes a wide range in feeding behavior: filter feeding and symbiosis with autotrophic phytoplankton as seen in corals.
Zooplankton feed on bacterioplankton, other zooplankton and nektonic organisms. As a result, zooplankton are found in surface waters where food resources are abundant. Just as any species can be limited within a geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean; as with phytoplankton, ‘patches’ of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic, specific species of zooplankton are restricted by salinity and temperature gradients. Zooplankton patchiness can be influenced by biological factors, as well as other physical factors. Biological factors include breeding, concentration of phytoplankton, vertical migration; the physical factor that influences zooplankton distribution the most is mixing of the water column that affects nutrient availability and, in turn, phytoplankton production. Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs, as a resource for consumers on higher trophic levels, as a conduit for packaging the organic material in the biological pump.
Since they are small, zooplankton can respond to increases in phytoplankton abundance, for instance, during the spring bloom. Zooplankton can act as a disease reservoir. Crustacean zooplankton have been found to house the bacterium Vibrio cholerae, which causes cholera, by allowing the cholera vibrios to attach to their chitinous exoskeletons; this symbiotic relationship enhances the bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen. Bacterioplankton Biological pump Census of Marine Zooplankton Diel vertical migration Gelatinous zooplankton Ocean acidification Phytoplankton Plankton Primary production SAHFOS Sir Alister Hardy Foundation for Ocean Science Ocean Drifters Short film narrated by David Attenborough about the varied roles of plankton Sea Drifters BBC Audio slideshow Plankton Chronicles Short documentary films & photos COPEPOD: The global plankton database. A global coverage database of zooplankton biomass and abundance data.
Guide to the marine zooplankton of south eastern Australia, Tasmanian Aquaculture and Fisheries Institute Australian Continuous Plankton Recorder Project An Image-Based Key to Zooplankton of North America
Russia the Russian Federation, is a transcontinental country in Eastern Europe and North Asia. At 17,125,200 square kilometres, Russia is by far or by a considerable margin the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, the ninth most populous, with about 146.77 million people as of 2019, including Crimea. About 77 % of the population live in the European part of the country. Russia's capital, Moscow, is one of the largest cities in the world and the second largest city in Europe. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Estonia, Latvia and Poland, Ukraine, Azerbaijan, China and North Korea, it shares maritime borders with Japan by the Sea of Okhotsk and the U. S. state of Alaska across the Bering Strait. However, Russia recognises two more countries that border it, Abkhazia and South Ossetia, both of which are internationally recognized as parts of Georgia.
The East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' disintegrated into a number of smaller states; the Grand Duchy of Moscow reunified the surrounding Russian principalities and achieved independence from the Golden Horde. By the 18th century, the nation had expanded through conquest and exploration to become the Russian Empire, the third largest empire in history, stretching from Poland on the west to Alaska on the east. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Union of Soviet Socialist Republics, the world's first constitutionally socialist state; the Soviet Union played a decisive role in the Allied victory in World War II, emerged as a recognized superpower and rival to the United States during the Cold War.
The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction. Following the dissolution of the Soviet Union in 1991, twelve independent republics emerged from the USSR: Russia, Belarus, Uzbekistan, Azerbaijan, Kyrgyzstan, Tajikistan and the Baltic states regained independence: Estonia, Lithuania, it is governed as a federal semi-presidential republic. Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2018. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it one of the leading producers of oil and natural gas globally; the country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction.
Russia is a great power as well as a regional power and has been characterised as a potential superpower. It is a permanent member of the United Nations Security Council and an active global partner of ASEAN, as well as a member of the Shanghai Cooperation Organisation, the G20, the Council of Europe, the Asia-Pacific Economic Cooperation, the Organization for Security and Co-operation in Europe, the World Trade Organization, as well as being the leading member of the Commonwealth of Independent States, the Collective Security Treaty Organization and one of the five members of the Eurasian Economic Union, along with Armenia, Belarus and Kyrgyzstan; the name Russia is derived from Rus', a medieval state populated by the East Slavs. However, this proper name became more prominent in the history, the country was called by its inhabitants "Русская Земля", which can be translated as "Russian Land" or "Land of Rus'". In order to distinguish this state from other states derived from it, it is denoted as Kievan Rus' by modern historiography.
The name Rus itself comes from the early medieval Rus' people, Swedish merchants and warriors who relocated from across the Baltic Sea and founded a state centered on Novgorod that became Kievan Rus. An old Latin version of the name Rus' was Ruthenia applied to the western and southern regions of Rus' that were adjacent to Catholic Europe; the current name of the country, Россия, comes from the Byzantine Greek designation of the Rus', Ρωσσία Rossía—spelled Ρωσία in Modern Greek. The standard way to refer to citizens of Russia is rossiyane in Russian. There are two Russian words which are commonly
The Decapoda or decapods are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, lobsters and shrimp. Most decapods are scavengers; the order is estimated to contain nearly 15,000 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 fossil decapod is the Devonian Palaeopalaemon. Decapods can have as many as 38 appendages, arranged in one pair per body segment; as the name Decapoda implies, ten of these appendages are considered legs. They are the pereiopods, found on the last five thoracic segments. In many decapods, one pair of these "legs" has enlarged pincers, called chelae, with the legs being called chelipeds. In front of the pereiopods are three pairs of maxillipeds which function as feeding appendages; the head has five pairs of appendages, including mouthparts and antennules.
There are five more pairs of appendages on the abdomen. They are called pleopods. There is one final pair called uropods, with the telson, form the tail fan. Classification within the order Decapoda depends on the structure of the gills and legs, the way in which the larvae develop, giving rise to two suborders: Dendrobranchiata and Pleocyemata; the Dendrobranchiata consist of prawns, including many species colloquially referred to as "shrimp", such as the "white shrimp", Litopenaeus setiferus. The Pleocyemata include the remaining groups, including "true shrimp"; those groups which walk rather than swim form a clade called Reptantia. This classification to the level of superfamilies follows De al.. Order Decapoda Latreille, 1802 Suborder Dendrobranchiata Bate, 1888 Penaeoidea Rafinesque, 1815 Sergestoidea Dana, 1852 Suborder Pleocyemata Burkenroad, 1963 Infraorder Stenopodidea Bate, 1888 Infraorder Caridea Dana, 1852 Procaridoidea Chace & Manning, 1972 Galatheacaridoidea Vereshchaka, 1997 Pasiphaeoidea Dana, 1852 Oplophoroidea Dana, 1852 Atyoidea De Haan, 1849 Bresilioidea Calman, 1896 Nematocarcinoidea Smith, 1884 Psalidopodoidea Wood-Mason, 1874 Stylodactyloidea Bate, 1888 Campylonotoidea Sollaud, 1913 Palaemonoidea Rafinesque, 1815 Alpheoidea Rafinesque, 1815 Processoidea Ortmann, 1896 Pandaloidea Haworth, 1825 Physetocaridoidea Chace, 1940 Crangonoidea Haworth, 1825 Infraorder Astacidea Latreille, 1802 Enoplometopoidea de Saint Laurent, 1988 Nephropoidea Dana, 1852 Astacoidea Latreille, 1802 Parastacoidea Huxley, 1879 Infraorder Glypheidea Winckler, 1882 Glypheoidea Winckler, 1882 Infraorder Axiidea de Saint Laurent, 1979b Infraorder Gebiidea de Saint Laurent, 1979 Infraorder Achelata Scholtz & Richter, 1995 Infraorder Polychelida Scholtz & Richter, 1995 Infraorder Anomura MacLeay, 1838 Aegloidea Dana, 1852 Galatheoidea Samouelle, 1819 Hippoidea Latreille, 1825a Chirostyloidea Ortmann, 1892 Lithodoidea Samouelle, 1819 Lomisoidea Bouvier, 1895 Paguroidea Latreille, 1802 Infraorder Brachyura Linnaeus, 1758 Section Dromiacea De Haan, 1833 Dromioidea De Haan, 1833 Homolodromioidea Alcock, 1900 Homoloidea De Haan, 1839 Section Raninoida De Haan, 1839 Section Cyclodorippoida Ortmann, 1892 Section Eubrachyura de Saint Laurent, 1980 Subsection Heterotremata Guinot, 1977 Aethroidea Dana, 1851 Bellioidea Dana, 1852 Bythograeoidea Williams, 1980 Calappoidea De Haan, 1833 Cancroidea Latreille, 1802 Carpilioidea Ortmann, 1893 Cheiragonoidea Ortmann, 1893 Corystoidea Samouelle, 1819 Dairoidea Serène, 1965 Dorippoidea MacLeay, 1838 Eriphioidea MacLeay, 1838 Gecarcinucoidea Rathbun, 1904 Goneplacoidea MacLeay, 1838 Hexapodoidea Miers, 1886 Leucosioidea Samouelle, 1819 Majoidea Samouelle, 1819 Orithyioidea Dana, 1852c Palicoidea Bouvier, 1898 Parthenopoidea MacLeay, Pilumnoidea Samouelle, 1819 Portunoidea Rafinesque, 1815 Potamoidea Ortmann, 1896 Pseudothelphusoidea Ortmann, 1893 Pseudozioidea Alcock, 1898 Retroplumoidea Gill, 1894 Trapezioidea Miers, 1886 Trichodactyloidea H. Milne-Edwards, 1853 Xanthoidea MacLeay, 1838 Subsection Thoracotremata Guinot, 1977 Cryptochiroidea Paul'son, 1875 Grapsoidea MacLeay, 1838 Ocypodoidea Rafinesque, 1815 Pinnotheroidea De Haan, 1833 List of Atlantic decapod species Phylogeny of Malacostraca Data related to Decapoda at Wikispecies Decapod Crustacea "Tree of Life" page at the Natural History Museum of Los Angeles County Decapoda at Curlie