10th edition of Systema Naturae
The 10th edition of Systema Naturae is a book written by Swedish naturalist Carolus Linnaeus and published in two volumes in 1758 and 1759, which marks the starting point of zoological nomenclature. In it, Linnaeus introduced binomial nomenclature for animals, something he had done for plants in his 1753 publication of Species Plantarum. Before 1758, most biological catalogues had used polynomial names for the taxa included, including earlier editions of Systema Naturae; the first work to apply binomial nomenclature across the animal kingdom was the 10th edition of Systema Naturae. The International Commission on Zoological Nomenclature therefore chose 1 January 1758 as the "starting point" for zoological nomenclature, asserted that the 10th edition of Systema Naturae was to be treated as if published on that date. Names published before that date are unavailable if they would otherwise satisfy the rules; the only work which takes priority over the 10th edition is Carl Alexander Clerck's Svenska Spindlar or Aranei Suecici, published in 1757, but is to be treated as if published on January 1, 1758.
During Linnaeus' lifetime, Systema Naturae was under continuous revision. Progress was incorporated into ever-expanding editions; the Animal Kingdom: Animals enjoy sensation by means of a living organization, animated by a medullary substance. They have members for the different purposes of life, they all originate from an egg. Their external and internal structure; the list has been broken down into the original six classes Linnaeus described for animals. These classes were created by studying the internal anatomy, as seen in his key: Heart with 2 auricles, 2 ventricles. Warm, red blood Viviparous: Mammalia Oviparous: Aves Heart with 1 auricle, 1 ventricle. Cold, red blood Lungs voluntary: Amphibia External gills: Pisces Heart with 1 auricle, 0 ventricles. Cold, pus-like blood Have antennae: Insecta Have tentacles: VermesBy current standards Pisces and Vermes are informal groupings, Insecta contained arachnids and crustaceans, one order of Amphibia comprised sharks and sturgeons. Linnaeus described mammals as: Animals.
In external and internal structure they resemble man: most of them are quadrupeds. The largest, though fewest in number, inhabit the ocean. Linnaeus divided the mammals based upon the number and structure of their teeth, into the following orders and genera: Primates: Homo, Lemur & Vespertilio Bruta: Elephas, Bradypus, Myrmecophaga & Manis Ferae: Phoca, Felis, Mustela & Ursus Bestiae: Sus, Erinaceus, Sorex & Didelphis Glires: Rhinoceros, Lepus, Mus & Sciurus Pecora: Camelus, Cervus, Ovis & Bos Belluae: Equus & Hippopotamus Cete: Monodon, Physeter & Delphinus Linnaeus described birds as: A beautiful and cheerful portion of created nature consisting of animals having a body covered with feathers and down, they are areal, vocal and light, destitute of external ears, teeth, womb, epiglottis, corpus callosum and its arch, diaphragm. Linnaeus divided the birds based upon the characters of the bill and feet, into the following 6 orders and 63 genera: Accipitres: Vultur, Strix & Lanius Picae: Psittacus, Buceros, Corvus, Gracula, Cuculus, Picus, Alcedo, Upupa, Certhia & Trochilus Anseres: Anas, Alca, Diomedea, Phaethon, Larus, Sterna & Rhyncops Grallae: Phoenicopterus, Mycteria & Tantulus, Scolopax, Charadrius, Haematopus, Rallus, Otis & Struthio Gallinae: Pavo, Crax, Phasianus & Tetrao Passeres: Columba, Sturnus, Loxia (cardina
Rhode Island the State of Rhode Island and Providence Plantations, is a state in the New England region of the United States. It is the smallest state in area, the seventh least populous, the second most densely populated, it has the longest official name of any state. Rhode Island is bordered by Connecticut to the west, Massachusetts to the north and east, the Atlantic Ocean to the south via Rhode Island Sound and Block Island Sound, it shares a small maritime border with New York. Providence is most populous city in Rhode Island. On May 4, 1776, the Colony of Rhode Island was the first of the Thirteen Colonies to renounce its allegiance to the British Crown, it was the fourth among the newly independent states to ratify the Articles of Confederation on February 9, 1778; the state boycotted the 1787 convention which drew up the United States Constitution and refused to ratify it. Rhode Island's official nickname is "The Ocean State", a reference to the large bays and inlets that amount to about 14 percent of its total area.
Despite its name, most of Rhode Island is located on the mainland of the United States. Its official name is State of Rhode Island and Providence Plantations, derived from the merger of four Colonial settlements; the settlements of Newport and Portsmouth were situated on what is called Aquidneck Island today, but it was called Rhode Island in Colonial times. Providence Plantation was the name of the colony founded by Roger Williams in the area now known as the city of Providence; this was adjoined by the settlement of Warwick. It is unclear how the island came to be named Rhode Island, but two historical events may have been of influence: Explorer Giovanni da Verrazzano noted the presence of an island near the mouth of Narragansett Bay in 1524 which he likened to the island of Rhodes. Subsequent European explorers were unable to identify the island that Verrazzano had named, but the Pilgrims who colonized the area assumed that it was this island. Adriaen Block passed by the island during his expeditions in the 1610s, he described it in a 1625 account of his travels as "an island of reddish appearance,", "een rodlich Eylande" in 17th-century Dutch, one popular notion is that this Dutch phrase might have influenced the name Rhode Island.
The earliest documented use of the name "Rhode Island" for Aquidneck was in 1637 by Roger Williams. The name was applied to the island in 1644 with these words: "Aquethneck shall be henceforth called the Isle of Rodes or Rhode-Island." The name "Isle of Rodes" is used in a legal document as late as 1646. Dutch maps as early as 1659 call the island "Red Island". Roger Williams was a theologian, forced out of the Massachusetts Bay Colony, seeking religious and political tolerance, he and others founded Providence Plantation as a free proprietary colony. "Providence" referred to the concept of divine providence, "plantation" was an English term for a colony. "State of Rhode Island and Providence Plantations" is the longest official name of any state in the Union. In recent years, the word plantation in the state's name became a contested issue, the Rhode Island General Assembly voted on June 25, 2009 to hold a general referendum determining whether "and Providence Plantations" would be dropped from the official name.
Advocates for excising plantation claimed that the word symbolized an alleged legacy of disenfranchisement for many Rhode Islanders, as well as the proliferation of slavery in the colonies and in the post-colonial United States. Rhode Island abolished slavery in 1652, but the law was not enforced and, by the early 18th century, it was "the epicenter of the North American slave trade", according to the Brown Daily Herald. Advocates for retaining the name argued that plantation was an archaic synonym for colony and bore no relation to slavery; the referendum election was held on November 2, 2010, the people voted overwhelmingly to retain the entire original name. In 1636, Roger Williams was banished from the Massachusetts Bay Colony for his religious views, he settled at the top of Narragansett Bay on land sold or given to him by Narragansett sachem Canonicus, he named the site Providence Plantations, "having a sense of God's merciful providence unto me in my distress", it became a place of religious freedom where all were welcome.
In 1638, Anne Hutchinson, William Coddington, John Clarke, Philip Sherman, other religious dissenters settled on Aquidneck Island, purchased from the local tribes who called it Pocasset. This settlement was governed by the Portsmouth Compact; the southern part of the island became the separate settlement of Newport after disagreements among the founders. Samuel Gorton purchased lands at Shawomet in 1642 from the Narragansetts, precipitating a dispute with the Massachusetts Bay Colony. In 1644, Providence and Newport united for their common independence as the Colony of Rhode Island and Providence Plantations, governed by an elected council and "president". Gorton received a separate charter for his settlement in 1648 which he named Warwick after his patron. Brown University was founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, it was one of nine Colonial colleges granted charters before the American Revolution, but was the first college in America to accept students regardless of religious affilia
Cape Cod is a geographic cape extending into the Atlantic Ocean from the southeastern corner of mainland Massachusetts, in the northeastern United States. Its historic, maritime character and ample beaches attract heavy tourism during the summer months; as defined by the Cape Cod Commission's enabling legislation, Cape Cod is conterminous with Barnstable County, Massachusetts. It extends from Provincetown in the northeast to Woods Hole in the southwest, is bordered by Plymouth to the northwest. Since 1914, most of Cape Cod has been separated from the mainland by the Cape Cod Canal; the canal cuts 7 miles across the base of the peninsula, though small portions of the Cape Cod towns of Bourne and Sandwich lie on the mainland side of the canal. Two highway bridges cross the Cape Cod Canal: the Bourne Bridge. In addition, the Cape Cod Canal Railroad Bridge carries railway freight and limited passenger services onto the Cape. Cape territory is divided into 15 towns with many villages. Like Cape Cod itself, the islands south of the Cape have evolved from whaling and trading areas to become resort destinations, attracting wealthy families and other tourists.
These include the large nearby islands of Nantucket and Martha's Vineyard, which have grown in population by 6.8 percent and 10.3 percent between 2000 and 2010 while the year-round population of Barnstable County dropped 3 percent according to the Census. Both islands are famous summer tourist destinations accessed by ferry from several locations on the cape; the phrases Cape Cod and the Islands and the Cape and Islands are used to describe the whole region of Barnstable County, Dukes County, Nantucket County. Several small islands right off Cape Cod, including Monomoy Island, Monomoscoy Island, Popponesset Island, Seconsett Island, are in Barnstable County; the Forbes family-owned Naushon Island was first purchased by John Murray Forbes. Naushon is one of the Elizabeth Islands, many of which are owned. One of the publicly accessible Elizabeths is the southernmost island in the chain, with a year-round population of 52 people. Several prominent families have established compounds or estates on the larger islands, making these islands some of the wealthiest resorts in the Northeast, yet they retain much of the early merchant trading and whaling culture.
Cape Cod in particular is a popular retirement area. And the average age of residents is the highest of any area in New England. By voter registration numbers, Democrats outnumber Republicans by less in the three counties than in the whole of Massachusetts, to varying degrees; the bulk of the land in the area is glacial terminal moraine and represents the southernmost extent of glacial coverage in southeast New England. The name "Cape Cod", as it was first used in 1602, applied only to the tip of the peninsula, it remained that way for 125 years, until the "Precinct of Cape Cod" was incorporated as the Town of Provincetown. No longer in "official" use over the ensuing decades, the name came to mean all of the land east of the Manomet and Scusset rivers – along the line that became the Cape Cod Canal; the creation of the canal separated the majority of the peninsula from the mainland. Most agencies, including the Cape Cod Commission and the Federal Emergency Management Agency, treat the Cape as an island with regard to disaster preparedness, groundwater management, the like.
Cape Codders tend to refer to the land on the mainland side of the canal as "off-Cape", though the legal delineation of Cape Cod, coincident to the boundaries of Barnstable County, includes portions of the towns of Bourne and Sandwich that are located north of the canal. Cape Cod Bay lies in between Cape Cod and the mainland – bounded on the north by a horizontal line between Provincetown and Marshfield. North of Cape Cod Bay is Massachusetts Bay, which contains the Stellwagen Bank National Marine Sanctuary, located 5 miles north of Provincetown; the Atlantic Ocean is to the east of Cape Cod, to the southwest of the Cape is Buzzards Bay. The Cape Cod Canal, completed in 1916, connects Buzzards Bay to Cape Cod Bay. Cape Cod extends 65 miles into the Atlantic Ocean, with a breadth of between 1–20 miles, covers more than 400 miles of shoreline, its elevation ranges from 306 feet at its highest point, at the top of Pine Hill, in the Bourne portion of Joint Base Cape Cod, down to sea level. One of the biggest barrier islands in the world, Cape Cod shields much of the Massachusetts coastline from North Atlantic storm waves.
This protection erodes the Cape's shoreline at the expense of its cliffs, while protecting towns from Fairhaven to Marshfield. Cape Cod and the Islands are part of a continuous archipelagic region consisting of a thin line of islands stretching west to include Long Island; this region is and collectively known by naturalists as the Outer Lands. Cape Cod incorporates all of Barnstable County, which comprises 15 towns: Bourne, Falmouth, Barnstable, Harwich, Brewster, Orleans, Wellfleet and Provincetown; each of these towns include a number of villages. Barnstable, the most populated municipality on Cape Cod, is the only one to have adopted a city form of government, whose legislative body is an elected 13-member council. However, like other smaller Massa
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
Mollusca is the second largest phylum of invertebrate animals. The members are known as mollusks. Around 85,000 extant species of molluscs are recognized; the number of fossil species is estimated between 100,000 additional species. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats, they are diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 8 or 9 taxonomic classes, of which two are extinct. Cephalopod molluscs, such as squid and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species; the gastropods are by far the most numerous molluscs and account for 80% of the total classified species. The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, the structure of the nervous system.
Other than these common elements, molluscs express great morphological diversity, so many textbooks base their descriptions on a "hypothetical ancestral mollusc". This has a single, "limpet-like" shell on top, made of proteins and chitin reinforced with calcium carbonate, is secreted by a mantle covering the whole upper surface; the underside of the animal consists of a single muscular "foot". Although molluscs are coelomates, the coelom tends to be small; the main body cavity is a hemocoel. The "generalized" mollusc's feeding system consists of a rasping "tongue", the radula, a complex digestive system in which exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles; the generalized mollusc has three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, all have sensors to detect chemicals and touch; the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur.
All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The coelomic cavity is reduced, they have kidney-like organs for excretion. Good evidence exists for the appearance of gastropods and bivalves in the Cambrian period, 541 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. Molluscs still are an important food source for anatomically modern humans. There is a risk of food poisoning from toxins which can accumulate in certain molluscs under specific conditions and because of this, many countries have regulations to reduce this risk. Molluscs have, for centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, sea silk, their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities.
The bite of the blue-ringed octopus is fatal, that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can kill, but their sophisticated, though produced, venoms have become important tools in neurological research. Schistosomiasis is transmitted to humans via water snail hosts, affects about 200 million people. Snails and slugs can be serious agricultural pests, accidental or deliberate introduction of some snail species into new environments has damaged some ecosystems; the words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, soft. Molluscus was itself an adaptation of Aristotle's τὰ μαλάκια ta malákia, which he applied inter alia to cuttlefish; the scientific study of molluscs is accordingly called malacology. The name Molluscoida was used to denote a division of the animal kingdom containing the brachiopods and tunicates, the members of the three groups having been supposed to somewhat resemble the molluscs.
As it is now known these groups have no relation to molluscs, little to one another, the name Molluscoida has been abandoned. The most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, the organization of the nervous system. Many have a calcareous shell. Molluscs have developed such a varied range of body structures, it is difficult to find synapomorphies to apply to all modern groups; the most general characteristic of molluscs is they are bilaterally symmetrical. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle which secretes calcareous spicules, plates or shells, it overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are two pairs of main nerve cords. Other characteristics that appear in textbooks have significant exceptions: Estimates of accepted described living species of molluscs vary from 50,000 to a maximum of 120,000 species.
In 1969 David Nicol estimated the probable total number of living mollusc species at 107,000 of which were ab
New England is a region composed of six states of the northeastern United States: Maine, New Hampshire, Rhode Island, Connecticut. It is bordered by the state of New York to the west and by the Canadian provinces of New Brunswick and Quebec to the northeast and north, respectively; the Atlantic Ocean is to the east and southeast, Long Island Sound is to the south. Boston is New England's largest city as well as the capital of Massachusetts; the largest metropolitan area is Greater Boston with nearly a third of the entire region's population, which includes Worcester, Manchester, New Hampshire, Providence, Rhode Island. In 1620, Puritan Separatist Pilgrims from England established Plymouth Colony, the second successful English settlement in America, following the Jamestown Settlement in Virginia founded in 1607. Ten years more Puritans established Massachusetts Bay Colony north of Plymouth Colony. Over the next 126 years, people in the region fought in four French and Indian Wars, until the English colonists and their Iroquois allies defeated the French and their Algonquian allies in America.
In 1692, the town of Salem and surrounding areas experienced the Salem witch trials, one of the most infamous cases of mass hysteria in history. In the late 18th century, political leaders from the New England colonies initiated resistance to Britain's taxes without the consent of the colonists. Residents of Rhode Island captured and burned a British ship, enforcing unpopular trade restrictions, residents of Boston threw British tea into the harbor. Britain responded with a series of punitive laws stripping Massachusetts of self-government which were termed the "Intolerable Acts" by the colonists; these confrontations led to the first battles of the American Revolutionary War in 1775 and the expulsion of the British authorities from the region in spring 1776. The region played a prominent role in the movement to abolish slavery in the United States, was the first region of the U. S. transformed by the Industrial Revolution, centered on the Merrimack river valleys. The physical geography of New England is diverse for such a small area.
Southeastern New England is covered by a narrow coastal plain, while the western and northern regions are dominated by the rolling hills and worn-down peaks of the northern end of the Appalachian Mountains. The Atlantic fall line lies close to the coast, which enabled numerous cities to take advantage of water power along the many rivers, such as the Connecticut River, which bisects the region from north to south; each state is subdivided into small incorporated municipalities known as towns, many of which are governed by town meetings. The only unincorporated areas exist in the sparsely populated northern regions of Maine, New Hampshire, Vermont. New England is one of the Census Bureau's nine regional divisions and the only multi-state region with clear, consistent boundaries, it maintains a strong sense of cultural identity, although the terms of this identity are contrasted, combining Puritanism with liberalism, agrarian life with industry, isolation with immigration. The earliest known inhabitants of New England were American Indians who spoke a variety of the Eastern Algonquian languages.
Prominent tribes included the Abenakis, Mi'kmaq, Pequots, Narragansetts and Wampanoag. Prior to the arrival of European settlers, the Western Abenakis inhabited New Hampshire, New York, Vermont, as well as parts of Quebec and western Maine, their principal town was Norridgewock in Maine. The Penobscot lived along the Penobscot River in Maine; the Narragansetts and smaller tribes under their sovereignty lived in Rhode Island, west of Narragansett Bay, including Block Island. The Wampanoag occupied southeastern Massachusetts, Rhode Island, the islands of Martha's Vineyard and Nantucket; the Pocumtucks lived in Western Massachusetts, the Mohegan and Pequot tribes lived in the Connecticut region. The Connecticut River Valley linked numerous tribes culturally and politically; as early as 1600, French and English traders began exploring the New World, trading metal and cloth for local beaver pelts. On April 10, 1606, King James I of England issued a charter for the Virginia Company, which comprised the London Company and the Plymouth Company.
These two funded ventures were intended to claim land for England, to conduct trade, to return a profit. In 1620, the Pilgrims arrived on the Mayflower and established Plymouth Colony in Massachusetts, beginning the history of permanent European settlement in New England. In 1616, English explorer John Smith named the region "New England"; the name was sanctioned on November 3, 1620 when the charter of the Virginia Company of Plymouth was replaced by a royal charter for the Plymouth Council for New England, a joint-stock company established to colonize and govern the region. The Pilgrims wrote and signed the Mayflower Compact before leaving the ship, it became their first governing document; the Massachusetts Bay Colony came to dominate the area and was established by royal charter in 1629 with its major town and port of Boston established in 1630. Massachusetts Puritans began to settle in Connecticut as early as 1633. Roger Williams was banished from Massachusetts for heresy, led a group south, founded Providence Plantation in the area that became the Colony of Rhode Island and Providence Plantations in 1636.
At this time, Vermont was yet unsettled, the territories of New Hampshire and Maine were claimed and governed by Massachusetts. Relationships between colonists and local Indian tribes alter
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