An estuary is a enclosed coastal body of brackish water with one or more rivers or streams flowing into it, with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments, they are subject both to marine influences—such as tides and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are classified according to their geomorphological features or to water-circulation patterns, they can have many different names, such as bays, lagoons, inlets, or sounds, although some of these water bodies do not meet the above definition of an estuary and may be saline.
The banks of many estuaries are amongst the most populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation and other poor farming practices; the word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary; the most accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, within which sea water is measurably diluted with freshwater derived from land drainage". However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff.
This broad definition includes fjords, river mouths, tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides; the sea water entering the estuary streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, the extent of evaporation of the water in the estuary. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley; this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border; the width-to-depth ratio of these estuaries is large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths exceed 30 m.
Examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, Delaware Bay along the Mid-Atlantic coast, Galveston Bay and Tampa Bay along the Gulf Coast. Bar-built estuaries are found in place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands, they are common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches encloses the estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries develop on sloping plains located along tectonically stable edges of continents and marginal sea coasts, they are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m. The barrier beaches that enclose bar-built estuaries have been developed in several ways: building up of offshore bars by wave action, in which sand from the sea floor is deposited in elongated bars parallel to the shoreline, reworking of sediment discharge from rivers by wave and wind action into beaches, overwash flats, dunes, engulfment of mainland beach ridges due to sea level rise and resulting in the breaching of the ridges and flooding of the coastal lowlands, forming shallow lagoons, elongation of barrier spits from the erosion of headlands due to the action of longshore currents, with the spits growing in the direction of the littoral drift.
Barrier beaches form in shallow water and are parallel to the shoreline, resulting in long, narrow estuaries. The average water depth is less than 5 m, exceeds 10 m. Examples of bar-built estuaries are Barnegat Bay, New Jersey. Fjords were formed where pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross s
The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago. The Miocene was named by Charles Lyell; the Miocene is followed by the Pliocene. As the earth went from the Oligocene through the Miocene and into the Pliocene, the climate cooled towards a series of ice ages; the Miocene boundaries are not marked by a single distinct global event but consist rather of regionally defined boundaries between the warmer Oligocene and the cooler Pliocene Epoch. The Apes first evolved and diversified during the early Miocene, becoming widespread in the Old World. By the end of this epoch and the start of the following one, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path during the final Messinian stage of the Miocene; as in the Oligocene before it, grasslands continued to forests to dwindle in extent. In the seas of the Miocene, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems.
The plants and animals of the Miocene were recognizably modern. Mammals and birds were well-established. Whales and kelp spread; the Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the geology of the Himalaya occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glacial periods in the northern hemisphere. The Miocene faunal stages from youngest to oldest are named according to the International Commission on Stratigraphy: Regionally, other systems are used, based on characteristic land mammals. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula. Mountain building took place in western North America and East Asia. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines.
Well studied continental exposures occur in Argentina. India continued creating dramatic new mountain ranges; the Tethys Seaway continued to shrink and disappeared as Africa collided with Eurasia in the Turkish–Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea near the end of the Miocene; the global trend was towards increasing aridity caused by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the late Miocene was responsible for the shrinking of tropical rain forests in that region, Australia got drier as it entered a zone of low rainfall in the Late Miocene. During the Oligocene and Early Miocene the coast of northern Brazil, south-central Peru, central Chile and large swathes of inland Patagonia were subject to a marine transgression; the transgressions in the west coast of South America is thought to be caused by a regional phenomenon while the rising central segment of the Andes represents an exception.
While there are numerous registers of Oligo-Miocene transgressions around the world it is doubtful that these correlate. It is thought that the Oligo-Miocene transgression in Patagonia could have temporarily linked the Pacific and Atlantic Oceans, as inferred from the findings of marine invertebrate fossils of both Atlantic and Pacific affinity in La Cascada Formation. Connection would have occurred through narrow epicontinental seaways that formed channels in a dissected topography; the Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene, forming the Chile Triple Junction. At first the Antarctic Plate subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan; as the southern part of Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate begun to subduct beneath Patagonia so that the Chile Triple Junction advanced to the north over time.
The asthenospheric window associated to the triple junction disturbed previous patterns of mantle convection beneath Patagonia inducing an uplift of ca. 1 km that reversed the Oligocene–Miocene transgression. Climates remained moderately warm, although the slow global cooling that led to the Pleistocene glaciations continued. Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivalled that of the Oligocene; the Miocene warming b
The nematodes or roundworms constitute the phylum Nematoda. They are a diverse animal phylum inhabiting a broad range of environments. Taxonomically, they are classified along with insects and other moulting animals in the clade Ecdysozoa, unlike flatworms, have tubular digestive systems with openings at both ends. Nematode species can be difficult to distinguish from one another. Estimates of the number of nematode species described to date vary by author and may change over time. A 2013 survey of animal biodiversity published in the mega journal Zootaxa puts this figure at over 25,000. Estimates of the total number of extant species are subject to greater variation. A referenced article published in 1993 estimated there may be over 1 million species of nematode, a claim which has since been repeated in numerous publications, without additional investigation, in an attempt to accentuate the importance and ubiquity of nematodes in the global ecosystem. Many other publications have since vigorously refuted this claim on the grounds that it is unsupported by fact, is the result of speculation and sensationalism.
More recent, fact-based estimates have placed the true figure closer to 40,000 species worldwide. Nematodes have adapted to nearly every ecosystem: from marine to fresh water, from the polar regions to the tropics, as well as the highest to the lowest of elevations, they are ubiquitous in freshwater and terrestrial environments, where they outnumber other animals in both individual and species counts, are found in locations as diverse as mountains and oceanic trenches. They are found in every part of the earth's lithosphere at great depths, 0.9–3.6 km below the surface of the Earth in gold mines in South Africa. They represent 90% of all animals on the ocean floor, their numerical dominance exceeding a million individuals per square meter and accounting for about 80% of all individual animals on earth, their diversity of lifecycles, their presence at various trophic levels point to an important role in many ecosystems. They have been shown to play crucial roles in polar ecosystem; the 2,271 genera are placed in 256 families.
The many parasitic forms include pathogens in animals. A third of the genera occur as parasites of vertebrates. Nathan Cobb, a nematologist, described the ubiquity of nematodes on Earth as thus:In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, if, as disembodied spirits, we could investigate it, we should find its mountains, vales, rivers and oceans represented by a film of nematodes; the location of towns would be decipherable, since for every massing of human beings, there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our highways; the location of the various plants and animals would still be decipherable, had we sufficient knowledge, in many cases their species could be determined by an examination of their erstwhile nematode parasites. Modern Latin compound of nemat- "thread" + -odes "like, of the nature of". In 1758, Linnaeus described some nematode genera included in the Vermes.
The name of the group Nematoda, informally called "nematodes", came from Nematoidea defined by Karl Rudolphi, from Ancient Greek νῆμα and -eiδἠς. It was treated as family Nematodes by Burmeister. At its origin, the "Nematoidea" erroneously included Nematodes and Nematomorpha, attributed by von Siebold. Along with Acanthocephala and Cestoidea, it formed the obsolete group Entozoa, created by Rudolphi, they were classed along with Acanthocephala in the obsolete phylum Nemathelminthes by Gegenbaur. In 1861, K. M. Diesing treated the group as order Nematoda. In 1877, the taxon Nematoidea, including the family Gordiidae, was promoted to the rank of phylum by Ray Lankester; the first clear distinction between the nemas and gordiids was realized by Vejdovsky when he named a group to contain the horsehair worms the order Nematomorpha. In 1919, Nathan Cobb proposed, he argued they should be called "nema" in English rather than "nematodes" and defined the taxon Nemates, listing Nematoidea sensu restricto as a synonym.
However, in 1910, Grobben proposed the phylum Aschelminthes and the nematodes were included in as class Nematoda along with class Rotifera, class Gastrotricha, class Kinorhyncha, class Priapulida, class Nematomorpha. In 1932, Potts elevated the class Nematoda to the level of phylum. Despite Potts' classification being equivalent to Cobbs', both names have been used and Nematode became a popular term in zoological science. Since Cobb was the first to include nematodes in a particular phylum separated from Nematomorpha, some researchers consider the valid taxon name to be Nemates or Nemata, rather than Nematoda, because of the zoological rule that gives priority to the first used term in case of synonyms; the phylogenetic relationships of the nematodes and their close relatives among the protostomian Metazoa are unresolved. Traditionally, they were held to b
Overfishing is the removal of a species of fish from a body of water at a rate that the species cannot replenish in time, resulting in those species either becoming depleted or underpopulated in that given area. Overfishing has been present for centuries. Overfishing can occur in water bodies of any sizes, such as ponds, lakes or oceans, can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing can lead to critical depensation, where the fish population is no longer able to sustain itself; some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire marine ecosystems. The ability of a fishery to recover from overfishing depends on whether the ecosystem's conditions are suitable for the recovery. Dramatic changes in species composition can result in an ecosystem shift, where other equilibrium energy flows involve species compositions different from those, present before the depletion of the original fish stock.
For example, once trout have been overfished, carp might take over in a way that makes it impossible for the trout to re-establish a breeding population. Overfishing has stripped many fisheries around the world of their stocks; the United Nations Food and Agriculture Organization estimated in a 2018 report that 33.1% of world fish stocks are subject to overfishing. Significant overfishing has been observed in pre-industrial times. In particular, the overfishing of the western Atlantic Ocean from the earliest days of European colonisation of the Americas has been well documented. Daniel Pauly, a fisheries scientist known for pioneering work on the human impacts on global fisheries, has commented: It is as though we use our military to fight the animals in the ocean. We are winning this war to exterminate them, and to see this destruction happen, for nothing – for no reason –, a bit frustrating. Strangely enough, these effects are all reversible, all the animals that have disappeared would reappear, all the animals that were small would grow, all the relationships that you can't see any more would re-establish themselves, the system would re-emerge.
Examples of overfishing exist in areas such as the North Sea, the Grand Banks of Newfoundland and the East China Sea. In these locations, overfishing has not only proved disastrous to fish stocks but to the fishing communities relying on the harvest. Like other extractive industries such as forestry and hunting, fisheries are susceptible to economic interaction between ownership or stewardship and sustainability, otherwise known as the tragedy of the commons; the Peruvian coastal anchovy fisheries crashed in the 1970s after overfishing and an El Niño season depleted anchovies from its waters. Anchovies were a major natural resource in Peru. However, the following five years saw the Peruvian fleet's catch amount to only about 4 million tons; this was a major loss to Peru's economy. The collapse of the cod fishery off Newfoundland, the 1992 decision by Canada to impose an indefinite moratorium on the Grand Banks, is a dramatic example of the consequences of overfishing; the sole fisheries in the Irish Sea, the west English Channel, other locations have become overfished to the point of virtual collapse, according to the UK government's official Biodiversity Action Plan.
The United Kingdom has created elements within this plan to attempt to restore this fishery, but the expanding global human population and the expanding demand for fish has reached a point where demand for food threatens the stability of these fisheries, if not the species' survival. Many deep sea fish are at risk, such as orange sablefish; the deep sea is completely dark, near freezing and has little food. Deep sea fish grow because of limited food, have slow metabolisms, low reproductive rates, many don't reach breeding maturity for 30 to 40 years. A fillet of orange roughy at the store is at least 50 years old. Most deep sea fish are in international waters. Most of these fish are caught by deep trawlers near seamounts, where they congregate because of food. Flash freezing allows the trawlers to work for days at a time, modern fishfinders target the fish with ease. Blue walleye became extinct in the Great Lakes in the 1980s; until the middle of the 20th century, it was a commercially valuable fish, with about a half million tonnes being landed during the period from about 1880 to the late 1950s, when the populations collapsed through a combination of overfishing, anthropogenic eutrophication, competition with the introduced rainbow smelt.
The World Wide Fund for Nature and the Zoological Society of London jointly issued their "Living Blue Planet Report" on 16 September 2015 which states that there was a dramatic fall of 74% in worldwide stocks of the important scombridae fish such as mackerel and bonitos between 1970 and 2010, the global overall "population sizes of mammals, reptiles and fish fell by half on average in just 40 years." Several countries are now managing their fisheries. Examples include New Zealand; the United States has turned many of its fisheries around from being in a depleted state. According to a 2008 UN report, the world's fishing fleets are losing US$50 billion each year through depleted stocks and poor fisheries management; the report, produced jointly by the World Bank and the UN Food and Agriculture Organization, asserts that half the world's fishing fleet could be scrapped with no change in catch. In addition, the biomass of global fish stocks have been allowed to run down to the point where it is no longer possible to cat
Massachusetts the Commonwealth of Massachusetts, is the most populous state in the New England region of the northeastern United States. It borders on the Atlantic Ocean to the east, the states of Connecticut and Rhode Island to the south, New Hampshire and Vermont to the north, New York to the west; the state is named after the Massachusett tribe, which once inhabited the east side of the area, is one of the original thirteen states. The capital of Massachusetts is Boston, the most populous city in New England. Over 80% of Massachusetts's population lives in the Greater Boston metropolitan area, a region influential upon American history and industry. Dependent on agriculture and trade, Massachusetts was transformed into a manufacturing center during the Industrial Revolution. During the 20th century, Massachusetts's economy shifted from manufacturing to services. Modern Massachusetts is a global leader in biotechnology, higher education and maritime trade. Plymouth was the site of the second colony in New England after Popham Colony in 1607 in what is now Maine.
Plymouth was founded in 1620 by passengers of the Mayflower. In 1692, the town of Salem and surrounding areas experienced one of America's most infamous cases of mass hysteria, the Salem witch trials. In 1777, General Henry Knox founded the Springfield Armory, which during the Industrial Revolution catalyzed numerous important technological advances, including interchangeable parts. In 1786, Shays' Rebellion, a populist revolt led by disaffected American Revolutionary War veterans, influenced the United States Constitutional Convention. In the 18th century, the Protestant First Great Awakening, which swept the Atlantic World, originated from the pulpit of Northampton preacher Jonathan Edwards. In the late 18th century, Boston became known as the "Cradle of Liberty" for the agitation there that led to the American Revolution; the entire Commonwealth of Massachusetts has played a powerful commercial and cultural role in the history of the United States. Before the American Civil War, Massachusetts was a center for the abolitionist and transcendentalist movements.
In the late 19th century, the sports of basketball and volleyball were invented in the western Massachusetts cities of Springfield and Holyoke, respectively. In 2004, Massachusetts became the first U. S. state to recognize same-sex marriage as a result of the decision in Goodridge v. Department of Public Health by the Massachusetts Supreme Judicial Court. Many prominent American political dynasties have hailed from the state, including the Adams and Kennedy families. Harvard University in Cambridge is the oldest institution of higher learning in the United States, with the largest financial endowment of any university, Harvard Law School has educated a contemporaneous majority of Justices of the Supreme Court of the United States. Kendall Square in Cambridge has been called "the most innovative square mile on the planet", in reference to the high concentration of entrepreneurial start-ups and quality of innovation which have emerged in the vicinity of the square since 2010. Both Harvard University and the Massachusetts Institute of Technology in Cambridge, have been ranked among the most regarded academic institutions in the world.
Massachusetts' public-school students place among the top tier in the world in academic performance, the state has been ranked as one of the top states in the United States for citizens to live in, as well as one of the most expensive. The Massachusetts Bay Colony was named after the indigenous population, the Massachusett derived from a Wôpanâak word muswach8sut, segmented as mus "big" + wach8 "mountain" + -s "diminutive" + -ut "locative", it has been translated as "near the great hill", "by the blue hills", "at the little big hill", or "at the range of hills", referring to the Blue Hills, or in particular the Great Blue Hill, located on the boundary of Milton and Canton. Alternatively, Massachusett has been represented as Moswetuset—from the name of the Moswetuset Hummock in Quincy, where Plymouth Colony commander Myles Standish, hired English military officer, Squanto, part of the now disappeared Patuxet band of the Wampanoag peoples, met Chief Chickatawbut in 1621; the official name of the state is the "Commonwealth of Massachusetts".
While this designation is part of the state's official name, it has no practical implications. Massachusetts has powers within the United States as other states, it may have been chosen by John Adams for the second draft of the Massachusetts Constitution because unlike the word "state", "commonwealth" at the time had the connotation of a republic, in contrast to the monarchy the former American colonies were fighting against. Massachusetts was inhabited by tribes of the Algonquian language family such as the Wampanoag, Nipmuc, Pocomtuc and Massachusett. While cultivation of crops like squash and corn supplemented their diets, these tribes were dependent on hunting and fishing for most of their food. Villages consisted of lodges called wigwams as well as longhouses, tribes were led by male or female elders known as sachems. In the early 1600s, after contact had been made with Europeans, large numbers of the indigenous peoples in the northeast of what is now the United States were killed by virgin soil epidemics such as smallpox, measles and leptospirosis.
Between 1617 and 1619, smallpox killed ap
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Perciformes called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means "perch-like"; this group comprises over 10,000 species found in all aquatic ecosystems. The order contains about 160 families, the most of any order within the vertebrates, it is the most variably sized order of vertebrates, ranging from the 7-mm Schindleria brevipinguis to the 5-m marlin in the genus Makaira. They first diversified in the Late Cretaceous. Among the well-known members of this group are perch and darters, sea bass and groupers; the dorsal and anal fins are divided into anterior spiny and posterior soft-rayed portions, which may be or separated. The pelvic fins have one spine and up to five soft rays, positioned unusually far forward under the chin or under the belly. Scales are ctenoid, although sometimes they are cycloid or otherwise modified. Classification is controversial.
As traditionally defined before the introduction of cladistics, the Perciformes are certainly paraphyletic. Other orders that should be included as suborders are the Scorpaeniformes, Tetraodontiformes, Pleuronectiformes. Of the presently recognized suborders, several may be paraphyletic, as well; these are grouped by suborder/superfamily following the text Fishes of the World. Photos of Perciformes on Sealife Collection