United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, the natural hazards that threaten it; the organization has four major science disciplines, concerning biology, geography and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility; the USGS is a bureau of the United States Department of the Interior. The USGS employs 8,670 people and is headquartered in Reston, Virginia; the USGS has major offices near Lakewood, Colorado, at the Denver Federal Center, Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world." The agency's previous slogan, adopted on the occasion of its hundredth anniversary, was "Earth Science in the Public Service." Since 2012, the USGS science focus is directed at six topical "Mission Areas", namely Climate and Land Use Change, Core Science Systems, Ecosystems and Minerals and Environmental Health, Natural Hazards, Water.
In December 2012, the USGS split the Energy and Minerals and Environmental Health Mission Area resulting in seven topical Mission Areas, with the two new areas being: Energy and Minerals and Environmental Health. Administratively, it is divided into six Regional Units. Other specific programs include: Earthquake Hazards Program monitors earthquake activity worldwide; the National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location and magnitude of global earthquakes. The USGS runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System; the USGS informs authorities, emergency responders, the media, the public, both domestic and worldwide, about significant earthquakes. It maintains long-term archives of earthquake data for scientific and engineering research, it conducts and supports research on long-term seismic hazards. USGS has released the UCERF California earthquake forecast.
As of 2005, the agency is working to create a National Volcano Early Warning System by improving the instrumentation monitoring the 169 volcanoes in U. S. territory and by establishing methods for measuring the relative threats posed at each site. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time; the USGS collaborates with Canadian and Mexican government scientists, along with the Commission for Environmental Cooperation, to produce the North American Environmental Atlas, used to depict and track environmental issues for a continental perspective. The USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online. National Climate Change and Wildlife Science Center implements partner-driven science to improve understanding of past and present land use change, develops relevant climate and land use forecasts, identifies lands and communities that are most vulnerable to adverse impacts of change from the local to global scale.
Since 1962, the Astrogeology Research Program has been involved in global and planetary exploration and mapping. In collaboration with Stanford University, the USGS operates the USGS-Stanford Ion Microprobe Laboratory, a world-class analytical facility for U--Pb geochronology and trace element analyses of minerals and other earth materials. USGS operates a number of water related programs, notably the National Streamflow Information Program and National Water-Quality Assessment Program. USGS Water data is publicly available from their National Water Information System database; the USGS operates the National Wildlife Health Center, whose mission is "to serve the nation and its natural resources by providing sound science and technical support, to disseminate information to promote science-based decisions affecting wildlife and ecosystem health. The NWHC provides information, technical assistance, research and leadership on national and international wildlife health issues." It is the agency responsible for surveillance of H5N1 avian influenza outbreaks in the United States.
The USGS runs 17 biological research centers in the United States, including the Patuxent Wildlife Research Center. The USGS is investigating collaboration with the social networking site Twitter to allow for more rapid construction of ShakeMaps; the USGS produces several national series of topographic maps which vary in scale and extent, with some wide gaps in coverage, notably the complete absence of 1:50,000 scale topographic maps or their equivalent. The largest and best-known topographic series is the 7.5-minute, 1:24,000 scale, quadrangle, a non-metric scale unique to the United States. Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart. Nearly 57,000 individual maps in this series cover the 48 contiguous states, Hawaii, U. S. territories, areas of Alaska near Anchorage and Prudhoe Bay. The area covered by each map varies with the latitude of its represented location due to convergence of the meridians. At lower latitudes, near 30° north, a 7.5-minute quadrangle contains an area of about 64 square miles.
At 49° north latitude, 49 square miles are contained within a quadrangle of that size. As a unique non-metric map scale, the 1:24,000 scale requires a separate and specialized romer scale for pl
Tennessee is a state located in the southeastern region of the United States. Tennessee is the 16th most populous of the 50 United States. Tennessee is bordered by Kentucky to the north, Virginia to the northeast, North Carolina to the east, Georgia and Mississippi to the south, Arkansas to the west, Missouri to the northwest; the Appalachian Mountains dominate the eastern part of the state, the Mississippi River forms the state's western border. Nashville is the state's capital and largest city, with a 2017 population of 667,560. Tennessee's second largest city is Memphis, which had a population of 652,236 in 2017; the state of Tennessee is rooted in the Watauga Association, a 1772 frontier pact regarded as the first constitutional government west of the Appalachians. What is now Tennessee was part of North Carolina, part of the Southwest Territory. Tennessee was admitted to the Union as the 16th state on June 1, 1796. Tennessee was the last state to leave the Union and join the Confederacy at the outbreak of the American Civil War in 1861.
Occupied by Union forces from 1862, it was the first state to be readmitted to the Union at the end of the war. Tennessee furnished more soldiers for the Confederate Army than any other state besides Virginia, more soldiers for the Union Army than the rest of the Confederacy combined. Beginning during Reconstruction, it had competitive party politics, but a Democratic takeover in the late 1880s resulted in passage of disenfranchisement laws that excluded most blacks and many poor whites from voting; this reduced competition in politics in the state until after passage of civil rights legislation in the mid-20th century. In the 20th century, Tennessee transitioned from an agrarian economy to a more diversified economy, aided by massive federal investment in the Tennessee Valley Authority and, in the early 1940s, the city of Oak Ridge; this city was established to house the Manhattan Project's uranium enrichment facilities, helping to build the world's first atomic bombs, two of which were dropped on Imperial Japan near the end of World War II.
Tennessee's major industries include agriculture and tourism. Poultry and cattle are the state's primary agricultural products, major manufacturing exports include chemicals, transportation equipment, electrical equipment; the Great Smoky Mountains National Park, the nation's most visited national park, is headquartered in the eastern part of the state, a section of the Appalachian Trail follows the Tennessee-North Carolina border. Other major tourist attractions include the Tennessee Aquarium in Chattanooga; the earliest variant of the name that became Tennessee was recorded by Captain Juan Pardo, the Spanish explorer, when he and his men passed through an American Indian village named "Tanasqui" in 1567 while traveling inland from South Carolina. In the early 18th century, British traders encountered a Cherokee town named Tanasi in present-day Monroe County, Tennessee; the town was located on a river of the same name, appears on maps as early as 1725. It is not known whether this was the same town as the one encountered by Juan Pardo, although recent research suggests that Pardo's "Tanasqui" was located at the confluence of the Pigeon River and the French Broad River, near modern Newport.
The meaning and origin of the word are uncertain. Some accounts suggest, it has been said to mean "meeting place", "winding river", or "river of the great bend". According to ethnographer James Mooney, the name "can not be analyzed" and its meaning is lost; the modern spelling, Tennessee, is attributed to James Glen, the governor of South Carolina, who used this spelling in his official correspondence during the 1750s. The spelling was popularized by the publication of Henry Timberlake's "Draught of the Cherokee Country" in 1765. In 1788, North Carolina created "Tennessee County", the third county to be established in what is now Middle Tennessee; when a constitutional convention met in 1796 to organize a new state out of the Southwest Territory, it adopted "Tennessee" as the name of the state. Tennessee is known as The Volunteer State, a nickname some claimed was earned during the War of 1812 because of the prominent role played by volunteer soldiers from Tennessee during the Battle of New Orleans.
Other sources differ on the origin of the state nickname. This explanation is more because President Polk's call for 2,600 nationwide volunteers at the beginning of the Mexican–American War resulted in 30,000 volunteers from Tennessee alone in response to the death of Davy Crockett and appeals by former Tennessee Governor and Texas politician, Sam Houston. Tennessee borders eight other states: Virginia to the north. Tennessee is tied with Missouri as the state bordering the most other states; the state is trisected by the Tennessee River. The highest point in the state is Clingmans Dome at 6,643 feet (
North America is a continent within the Northern Hemisphere and all within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16.5% of the earth's land area and about 4.8% of its total surface. North America is the third largest continent by area, following Asia and Africa, the fourth by population after Asia and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population, if nearby islands are included. North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge 40,000 to 17,000 years ago; the so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago. The Classic stage spans the 6th to 13th centuries.
The Pre-Columbian era ended in 1492, the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves and their descendants. Owing to the European colonization of the Americas, most North Americans speak English, Spanish or French, their culture reflects Western traditions; the Americas are accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass unknown by Europeans. In 1507, Waldseemüller produced a world map, in which he placed the word "America" on the continent of South America, in the middle of what is today Brazil, he explained the rationale for the name in the accompanying book Cosmographiae Introductio:... ab Americo inventore... quasi Americi terram sive Americam.
For Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespucci's name, but in its feminine form "America", following the examples of "Europa", "Asia" and "Africa". Other mapmakers extended the name America to the northern continent, In 1538, Gerard Mercator used America on his map of the world for all the Western Hemisphere; some argue that because the convention is to use the surname for naming discoveries, the derivation from "Amerigo Vespucci" could be put in question. In 1874, Thomas Belt proposed a derivation from the Amerrique mountains of Central America. Marcou corresponded with Augustus Le Plongeon, who wrote: "The name AMERICA or AMERRIQUE in the Mayan language means, a country of perpetually strong wind, or the Land of the Wind, and... the can mean... a spirit that breathes, life itself." The United Nations formally recognizes "North America" as comprising three areas: Northern America, Central America, The Caribbean.
This has been formally defined by the UN Statistics Division. The term North America maintains various definitions in accordance with context. In Canadian English, North America refers to the land mass as a whole consisting of Mexico, the United States, Canada, although it is ambiguous which other countries are included, is defined by context. In the United States of America, usage of the term may refer only to Canada and the US, sometimes includes Greenland and Mexico, as well as offshore islands. In France, Portugal, Romania and the countries of Latin America, the cognates of North America designate a subcontinent of the Americas comprising Canada, the United States, Mexico, Greenland, Saint Pierre et Miquelon, Bermuda. North America has been referred to by other names. Spanish North America was referred to as Northern America, this was the first official name given to Mexico. Geographically the North American continent has many subregions; these include cultural and geographic regions. Economic regions included those formed by trade blocs, such as the North American Trade Agreement bloc and Central American Trade Agreement.
Linguistically and culturally, the continent could be divided into Latin America. Anglo-America includes most of Northern America and Caribbean islands with English-speaking populations; the southern North American continent is composed of two regions. These are the Caribbean; the north of the continent maintains recognized regions as well. In contrast to the common definition of "North America", which encompasses the whole continent, the term "North America" is sometimes used to refer only to Mexico, the United States, Greenland; the term Northern America refers to the northern-most countries and territories of North America: the United States, Bermuda, St. Pierre and Miquelon and Greenland. Although the term does not refer to a unifie
Bowfishing is a method of fishing that uses specialized archery equipment to shoot and retrieve fish. Fish are shot with a barbed arrow, attached with special line to a reel mounted on the bow; some freshwater species hunted include common carp, grass carp, bighead carp, alligator gar, paddlefish. In saltwater and sharks are pursued. Bows are very simple. Most do not have sights, aiming is by line-of-sight judgment down the arrow. There are a couple of types of rests including the roller rest. Most bows have little to no not much draw weight; this differs with what one has personal preference. There are two main types of bows. Traditional bows include long bows and recurve bows. In more modern times, compound bows came into use, they use a system of pulleys to help the archer. Modern bows can have as much as 120 pounds draw weight; the crossbow is sometimes used in this manner and has its own advantages, including the use of a reel. See Recreational fishing. Bowfishing arrows are heavier and stronger than arrows used in other types of archery and are most constructed of five-sixteenth inch fiberglass, but solid aluminum, carbon fiber, carbon fiber reinforced fiberglass are used.
Bowfishing arrows lack fletching, as it can cause the arrow to flare to one side or another underwater and they are not required at the short ranges associated with bowfishing. Line is attached to the arrow by tying to a hole in the arrow shaft or through the use of a slide system. Bowfishing line is made from braided nylon, Dacron, or Spectra. Used line weights range from eighty to four-hundred pound test, with six-hundred being used when bowhunting for alligators. Line color is either lime green, white, or neon orange. Three types of reels are used in bowfishing: Hand-wrap and retriever. Hand-wrap reels are the simplest reels; when the arrow is shot the line feeds off the spool. Fish are caught by pulling the line in hand over hand. Retriever reels have a "bottle"; when shot the line comes out either until the shot goes too far and the line runs out or the hunter pushes down a stopping device which can be used to keep a fish from traveling out too far. Some retriever reels are known as slotted retriever reels.
They are more used for alligator, alligator gar and other big game that will take more time to chase down than smaller game fish. One of the keys to bowfishing is having a good visual of the target. In order to see the fish in the water on a sunny day, polarized sun glasses are helpful, they cut the glare on top of the water. Different tints and lens colors make a difference in the color of water the hunter is fishing in, from darker brown to clearer blue and green. At night glasses are unnecessary. Although bowfishing can be done from the shore, bowfishers most shoot from boats. Flat bottom "john boats" and canoes are used in areas of low water, as they have less draw, but are unsuitable for open water. Larger boats can accommodate multiple hunters. Many of these boats are customized for bowfishing, with raised shooting platforms, generators to provide electrical power to multiple lights for bowfishing at night. "Airboats" incorporate some type of fan propulsion for operating in shallow waters.
The fan and motor are mounted on a raised platform at the stern. Along with fishing from boats and off the shore and shooting is effective as long as the hunter doesn't mind getting soaked. Wading in rivers allows the shooter to get up close to the fish if the hunter is skillful; when keeping fish while wading, the hunter may utilize a stringer tied to a belt loop. Standing on large rocks in shallower parts of a river is another technique; this provides a better view higher out of the water. Going from rock to rock in a river with two hunters gets the fish moving if they are inactive, it is similar to herding the fish to the other hunter. All of these river techniques work best for carp or catfish, depending on the location. Knowing where to aim on a fish can be one of the most difficult skills to master in bowfishing. Due to the refraction of the water and how it optically distorts the location of objects in the water, aiming straight at the target results in a miss. Aiming well below the target compensates for the optical illusion.
Depth and distance of the target impact how far below the fish to aim. Aiming four inches low for every ten feet of lateral distance from the fish water, adding 3 inches for every foot of water depth in which the target resides yields good results, though actual compensation for refracted light must account not only for distance and depth, but angle as well. Common advice includes, "When in doubt, aim low aim lower." Bear, Fred. "Underwater Bowhunting". The Archer's Bible. Doubleday. Pp. 123–129. ISBN 0-385-15155-1. BowfishingForum.com – Bowfishing Forum Archery Fishing – Reel Fishing Reports
Actinopterygii, or the ray-finned fishes, constitute a class or subclass of the bony fishes. The ray-finned fishes are so called because their fins are webs of skin supported by bony or horny spines, as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii; these actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton. Numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish, they are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm, to the massive ocean sunfish, at 2,300 kg, the long-bodied oarfish, at 11 m. Ray-finned fishes occur in many variant forms; the main features of a typical ray-finned fish are shown in the adjacent diagram. In nearly all ray-finned fish, the sexes are separate, in most species the females spawn eggs that are fertilized externally with the male inseminating the eggs after they are laid.
Development proceeds with a free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism. In most cases this involves protogyny, fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry, where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization. Of the oviparous teleosts, most do not provide parental care. Viviparity, ovoviviparity, or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction of the 422 teleost families. Viviparity is rare and is found in about 6% of teleost species. Male territoriality "preadapts" a species for evolving male parental care. There are a few examples of fish; the mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation.
This mode of reproduction may be related to the fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are produced at temperatures below 19 °C and can fertilise eggs that are spawned by the female; this maintains genetic variability in a species, otherwise inbred. The earliest known fossil actinopterygiian is Andreolepis hedei. Remains have been found in Russia and Estonia. Actinopterygians are divided into the subclasses Neopterygii; the Neopterygii, in turn, are divided into the infraclasses Teleostei. During the Mesozoic and Cenozoic the teleosts in particular diversified and as a result, 96% of all known fish species are teleosts; the cladogram shows the major groups of actinopterygians and their relationship to the terrestrial vertebrates that evolved from a related group of fish. Approximate dates are from al.. 2012. The polypterids are the sister lineage of all other actinopterygians, the Acipenseriformes are the sister lineage of Neopterygii, Holostei are the sister lineage of teleosts.
The Elopomorpha appears to be the most basic teleosts. The listing below follows Phylogenetic Classification of Bony Fishes with notes when this differs from Nelson, ITIS and FishBase and extinct groups from Van der Laan 2016. Order †? Asarotiformes Schaeffer 1968 Order †? Discordichthyiformes Minikh 1998 Order †? Paphosisciformes Grogan & Lund 2015 Order †? Scanilepiformes Selezneya 1985 Order †Cheirolepidiformes Kazantseva-Selezneva 1977 Order †Paramblypteriformes Heyler 1969 Order †Rhadinichthyiformes Order †Palaeonisciformes Hay 1902 Order †Tarrasiiformes sensu Lund & Poplin 2002 Order †Ptycholepiformes Andrews et al. 1967 Order †Redfieldiiformes Berg 1940 Order †Haplolepidiformes Westoll 1944 Order †Aeduelliformes Heyler 1969 Order †Platysomiformes Aldinger 1937 Order †Dorypteriformes Cope 1871 Order †Eurynotiformes Sallan & Coates 2013 Subclass Cladistii Pander 1860 Order †Guildayichthyiformes Lund 2000 Order Polypteriformes Bleeker 1859 Clade Actinopteri Cope 1972 s.s. Order †Elonichthyiformes Kazantseva-Selezneva 1977 Order †Phanerorhynchiformes Order †Saurichthyiformes Berg 1937 Subclass Chondrostei Order †Birgeriiformes Jin 2001 Order †Chondrosteiformes Order Acipenseriformes Berg 1940 Subclass Neopterygii Regan 1923 sensu Xu & Wu 2012 Order †Pholidopleuriformes Berg 1937 Order †Peltopleuriformes Lehman 1966 Order †Perleidiformes Berg 1937 Order †Luganoiiformes Lehman 1958 Order †Pycnodontiformes Berg 1937 Infraclass Holostei Muller 1844 Division Halecomorpha Cope 1872 sensu Grande & Bemis 1998 Order †Parasemionotiformes Lehman 1966 Order †Ionoscopiformes Grande & Bemis 1998 Order Amiiformes Huxley 1861 sensu Grande & Bemis 1998 Division Ginglymodi Cope 1871 Order †Dapediiformes Thies & Waschkewitz 2015 Order †Semionotiformes Arambourg & Bertin 1958 Order Lepisosteiformes Hay 1929 Clade Teleosteomorpha Arratia 2000 sensu Arratia 2013 Order †Prohaleciteiformes Arratia 2017 Division Aspidorhynchei Nelson, Grand & Wilson 2016 Order †Aspidorhynchiformes Bleeker 1859 Order †Pachycormiformes Berg 1937 Infraclass Teleostei Müller 1844 sensu Arratia 2013 Order †?
Araripichthyiformes Order †? Ligulelliiformes Taverne 2011 Order †? Tselfatiiformes Nelson 1994 Order †Pholidophori
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of releasing the eggs and sperm, the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and reptiles, reproduce through the process of spawning. Spawn consists of the reproductive cells of many aquatic animals, some of which will become fertilized and produce offspring; the process of spawning involves females releasing ova into the water in large quantities, while males or sequentially release spermatozoa to fertilize the eggs. Most fish reproduce by spawning, as do most other aquatic animals, including crustaceans such as crabs and shrimps, molluscs such as oysters and squid, echinoderms such as sea urchins and sea cucumbers, amphibians such as frogs and newts, aquatic insects such as mayflies and mosquitoes and corals, which are small aquatic animals—not plants. Fungi, such as mushrooms, are said to "spawn" a white, fibrous matter that forms the matrix from which they grow.
There are many variations in the way spawning occurs, depending on sexual differences in anatomy, how the sexes relate to each other and how the spawn is released and whether or how the spawn is subsequently guarded. Marine animals, bony fish reproduce by broadcast spawning; this is an external method of reproduction where the female releases many unfertilised eggs into the water. At the same time, a male or many males release a lot of sperm into the water which fertilises some of these eggs; the eggs contain a drop of nutrient oil to sustain the embryo. The oil provides buoyancy, so the eggs float and drift with the current; the strategy for survival of broadcast spawning is to disperse the fertilised eggs, preferably away from the coast into the relative safety of the open ocean. There the larvae develop as they consume their fat stores, hatch from the egg capsule into miniature versions of their parents. To survive, they must become miniature predators themselves, feeding on plankton. Fish encounter others of their own kind, where they form aggregations and learn to school.
Internally, the sexes of most marine animals can be determined by looking at the gonads. For example, male testes of spawning fish are smooth and white and account for up to 12% of the mass of the fish, while female ovaries are granular and orange or yellow, accounting for up to 70% of the fish's mass. Male lampreys and salmon discharge their sperm into the body cavity where it is expelled through pores in the abdomen. Male sharks and rays can pass sperm along a duct into a seminal vesicle, where they store it for a while before it is expelled, while teleosts employ separate sperm ducts. Externally, many marine animals when spawning, show little sexual dimorphism or little difference in colouration. Where species are dimorphic, such as sharks or guppies, the males have penis-like intromittent organs in the form of a modified fin. A species is semelparous if its individuals spawn only once in their lifetime, iteroparous if its individuals spawn more than once; the term semelparity comes from the Latin semel and pario, to beget, while iteroparity comes from itero, to repeat, pario, to beget.
Semelparity is sometimes called "big bang" reproduction, since the single reproductive event of semelparous organisms is large and fatal to the spawners. The classic example of a semelparous animal is the Pacific salmon,which lives for many years in the ocean before swimming to the freshwater stream of its birth and dying. Other spawning animals which are semelparous include mayflies, octopus, smelt and some amphibians. Semelparity is associated with r-strategists. However, most fish and other spawning animals are iteroparous; when the internal ovaries or egg masses of fish and certain marine animals are ripe for spawning they are called roe. Roe from certain species, such as shrimp, scallop and sea urchins, are sought as human delicacies in many parts of the world. Caviar is a name for the processed, salted roe of non-fertilized sturgeon; the term soft roe or white roe denotes fish milt. Lobster roe is called coral. Roe are eaten either raw or cooked. "The reproductive behaviour of fishes is remarkably diversified: they may be oviparous, ovoviparous, or viviparous.
All cartilaginous fishes—the elasmobranches —employ internal fertilization and lay large, heavy-shelled eggs or give birth to live young. The most characteristic features of the more primitive bony fishes is the assemblage of polyandrous breeding aggregations in open water and the absence of parental care..."There are two main reproduction methods in fish. The first method is by laying the second by live-bearing. In the first method, the female fish lays eggs either on the sea floor or on the leaves of an aquatic plant. A male fish fertilizes the eggs, both work together to protect the eggs/babies from danger until they can defend themselves. In the second method, the male fish uses its anal fin to transmit sperm into the female fish and fertilize the fish eggs; the female gives live birth to her fry. Monogamy occurs; this is called pair spawning. Most fish are not monogamous, when they are, they alternate with non-mon