Grand Theft Auto IV theme by Man2Vir
Download: GTAIV_17.p3t
(3 backgrounds)
| Grand Theft Auto IV | |
|---|---|
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| Developer(s) | Rockstar North[a] |
| Publisher(s) | Rockstar Games |
| Producer(s) | Leslie Benzies |
| Programmer(s) |
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| Artist(s) | Aaron Garbut |
| Writer(s) |
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| Composer(s) | Michael Hunter |
| Series | Grand Theft Auto |
| Engine | RAGE |
| Platform(s) | |
| Release | PlayStation 3, Xbox 360
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| Genre(s) | Action-adventure |
| Mode(s) | Single-player, multiplayer |
Grand Theft Auto IV is a 2008 action-adventure game developed by Rockstar North and published by Rockstar Games. It is the sixth main entry in the Grand Theft Auto series, following 2004's Grand Theft Auto: San Andreas, and the eleventh entry overall. Set in the fictional Liberty City, based on New York City, the single-player story follows Eastern European war veteran Niko Bellic and his attempts to escape his past while under pressure from high-profile criminals. The open world design lets players freely roam Liberty City, consisting of three main islands, and the neighbouring state of Alderney, which is based on New Jersey.
The game is played from a third-person perspective and its world is navigated on foot and by vehicle. Throughout the single-player mode, players control Niko Bellic. An online multiplayer mode is also included with the game, allowing up to 32 players to engage in both cooperative and competitive gameplay in a recreation of the single-player setting.[b] Two expansion packs were later released for the game, The Lost and Damned and The Ballad of Gay Tony, which both feature new plots that are interconnected with the main Grand Theft Auto IV storyline, and follow new protagonists.
Development of Grand Theft Auto IV began soon after the release of San Andreas and was shared between many of Rockstar's studios worldwide. The game introduced a shift to a more realistic and detailed style and tone for the series. Unlike previous entries, Grand Theft Auto IV lacked a strong cinematic influence, as the team attempted an original approach to the story. As part of their research for the open world, the development team conducted extensive field research in New York, capturing over 100,000 photographs and several hours of video. The developers considered the world to be the most important element of the game; though not the largest map in the series, they considered it comparable in scope due to its verticality and level of detail. The budget climbed to over US$100 million, making it one of the most expensive video games to develop.
Grand Theft Auto IV was released for the PlayStation 3 and Xbox 360 consoles in April 2008, and for Windows in December. Upon release, the game received critical acclaim, with praise particularly directed at the narrative and open-world design. Grand Theft Auto IV broke industry sales records and became the fastest-selling entertainment product in history at the time, earning US$310 million in its first day and US$500 million in its first week. Considered one of the most significant titles of the seventh generation of video games, and by many critics as one of the greatest video games of all time, it won year-end accolades, including Game of the Year awards from several gaming publications. It is among the best-selling video games with over 25 million copies sold by 2013. The game generated controversy, with criticism directed at the game's depiction of violence and players' ability to drink-drive. Its successor, Grand Theft Auto V, was released in September 2013.
Gameplay[edit]
Grand Theft Auto IV is an action-adventure game played from a third-person perspective.[2] Players complete missions—linear scenarios with set objectives—to progress through the story. It is possible to have several active missions running at one time, as some require players to wait for further instructions or events. Outside of missions, players can freely roam the game's open world and complete optional side missions.[3] Composed of the fictional city of Liberty City, the world is larger in area than most earlier Grand Theft Auto series entries.[4] At the beginning of the game, players can only explore the first island—composed of Dukes and Broker—with all other islands unlocking as the story progresses.[5]
Players use melee attacks, firearms and explosives to fight enemies, and may run, jump, swim or use vehicles to navigate the game's world. There is a first-person perspective option when using vehicles. In combat, auto-aim and a cover system can be used as assistance against enemies. Should players take damage, their health meter can be fully regenerated by consuming food or drinks, using medical kits, or calling for paramedics.[6] If players commit crimes, the game's law enforcement agencies may respond as indicated by a "wanted" meter in the head-up display (HUD). On the meter, the displayed stars indicate the current wanted level (for example, at the maximum six-star level, efforts by law enforcement to incapacitate players become very aggressive). Law enforcement officers will search for players who leave the wanted vicinity. The wanted meter enters a cool-down mode and eventually recedes when players are hidden from the officers' line of sight.[7]
The game's cover system allows players to move between cover, to fire blindly, aim freely, and target a specific enemy. Individual body parts can also be targeted.[8] Melee attacks include additional moves, such as dodging, blocking, disarming an opponent and counter-attacking. Body armour can be used to absorb gunshots and explosive damage, but is used up in the process. When health is entirely depleted, gameplay stops, and players respawn at the nearest hospital.[6]
The single-player mode lets players control an Eastern European war veteran, Niko Bellic. During the story, Niko meets and befriends various new characters. They can then perform favours for Niko whenever he asks; for example, his cousin Roman, who owns a taxi service, can send one of his cabs to take Niko to any destination around the city. Cabs are always available during gameplay for quick travel to a destination. Throughout the course of the game, players are also faced with morality choices, which alter the storyline appropriately depending on the player's choice. While free roaming the game world, players may engage in context-specific activities such as bowling or darts. Other available activities include a vigilante mini-game, and in-game television programming.[9][10][11] Niko has a cell phone for contacting friends and starting activities.[12] The cell phone is also used to access the game's online multiplayer mode, and to enter cheat codes.[13] To access the in-game Internet, which allows Niko to send and receive emails and set up prospective dates with potential girlfriends, Niko can use Internet cafés located around the city.[14] The game also features a subway system, allowing players to quickly traverse through the game's world.[15]
The online multiplayer mode for Grand Theft Auto IV allows up to 32 players[b] to freely roam across the map. Players decide which game mode they wish to play, including deathmatches and street races. Both cooperative and competitive game modes are available, split into ranked and unranked matches.[16] For players to level up through ranks, in-game money has to be earned. The game also features a Free Mode, in which players have the entire map open to explore, with no end goal or mission to complete. Hosts of the game can control many variables, such as police presence, traffic, and weapons.[17] The multiplayer mode was discontinued on Windows in 2020.[18]
Synopsis[edit]
Setting[edit]
Grand Theft Auto IV takes place in 2008, within a redesigned version of Liberty City. The design of the city focuses on a recreation of four of the boroughs of New York City: Broker (based on Brooklyn), Dukes (Queens), Bohan (The Bronx), and Algonquin (Manhattan). The setting also includes the neighbouring state of Alderney (based on New Jersey).[19] Initially, bridges are locked down due to a terrorist threat, and police constantly pursue players if the bridges are crossed. The blockades are lifted as the story progresses, allowing the player to traverse between islands safely.
Grand Theft Auto IV is set in the fictional "HD Universe", which mirrors and parodies the real world. The previous games formed fictional universes of their own,[c] which despite having many similarities with the HD Universe, are considered to be different continuities. Hence, the Liberty City depicted in Grand Theft Auto IV is different from its previous renditions, and the game itself serves as a reboot for the series. The new timeline established by Grand Theft Auto IV would continue with two expansion packs, The Lost and Damned and The Ballad of Gay Tony, and a sequel, Grand Theft Auto V, as well as its online component, Grand Theft Auto Online.[21][22][23] The handheld game Grand Theft Auto: Chinatown Wars is also considered part of the HD Universe, because it features the same map as Grand Theft Auto IV, except for Alderney.[24]
Plot[edit]
Niko Bellic, an Eastern European ex-soldier,[25] arrives in Liberty City aboard a cargo ship, the Platypus, to escape his criminal past, pursue the American Dream, and search for the man who betrayed his unit to an ambush during a war ten years prior. Reuniting with his cousin Roman, he discovers that his tales of riches were lies concealing his small, dirty apartment, unprofitable taxi company, gambling debts, and disputes with loan sharks. Niko begins assisting Roman with his problems, which leads him to make his first criminal contacts in the city. He befriends Yardies second-in-command Little Jacob and is forced to work for Vlad Glebov, Roman's Russian loan shark, whom Niko eventually kills upon learning he had slept with Roman's girlfriend, Mallorie.
In retaliation, Niko and Roman are kidnapped by Russian mobsters on orders of their boss Mikhail Faustin and his lieutenant, Dimitri Rascalov. Indifferent to Vlad's murder, Faustin releases them and employs Niko as a hitman, eventually ordering him to kill the son of Russian crime lord Kenny Petrović. When Petrović threatens retaliation, Dimitri convinces Niko to assassinate Faustin. However, he then betrays and brings Niko to his former employer, Ray Bulgarin, who accuses Niko of stealing from him during a botched human trafficking job years earlier. Niko denies the allegation and a firefight ensues, allowing Dimitri and Bulgarin to escape.
Dimitri's men burn down Niko and Roman's apartment and taxi company, forcing them to flee to Bohan. While Niko finds work with several local drug lords, Dimitri kidnaps Roman in a failed attempt to lure Niko into a trap. Later, Niko discovers that his romantic interest, a woman named Michelle, is a government agent, who then entraps him into working for her agency. In exchange for the murders of several known or suspected terrorists, the agency clears Niko's criminal record and assists him in searching for the traitor he seeks. Niko and Roman's fortunes improve when the latter receives a large amount of insurance money from his destroyed business, which he uses to rebuild it and buy an apartment in Algonquin. Roman also proposes to Mallorie, who accepts.
While working for the Irish Mob, Niko befriends gangster Patrick "Packie" McReary and helps him and his brothers carry out various jobs, including a major bank robbery. Niko is later hired by Ray Boccino, a caporegime in the Pegorino crime family, to oversee a diamond deal, which goes awry. Boccino repays Niko by helping him find his ex-comrade Florian Cravic, now known as Bernie Crane, who claims he was not the one to betray their unit. Niko concludes that the traitor was Darko Brevic, the only other survivor. Niko continues working for the Mafia in Liberty City and eventually earns the trust of Don Jimmy Pegorino, who orders Niko to kill Boccino after suspecting him of being a police informant. Niko also helps Packie kidnap Don Giovanni Ancelotti's daughter to ransom her for the diamonds, but Bulgarin intercepts the exchange. In the ensuing firefight, the diamonds are lost.
Eventually, the government agents find Darko in Romania and bring him to Liberty City for Niko to decide his fate. Afterwards, Niko is summoned by Pegorino for one final favour: to help with a highly lucrative heroin deal in collusion with Dimitri. Niko must either agree to work with Dimitri or exact revenge on him.[26] If Niko goes through with the deal, Dimitri betrays him again,[27] kills Pegorino,[28] and attempts to kill Niko via an assassin at Roman's wedding, but accidentally kills Roman;[29] Niko retaliates by tracking and murdering Dimitri.[28] If Niko chooses to exact revenge, he kills Dimitri aboard the Platypus,[30] prompting a furious Pegorino to target Niko but accidentally kill Packie's sister Kate, whom Niko had been dating, at Roman's wedding;[29] Niko retaliates by tracking and murdering Pegorino.[31] Later, either Mallorie or Roman tells Niko that Mallorie is pregnant.
Development[edit]
Preliminary work on Grand Theft Auto IV began in November 2004,[32] a month after the release of Grand Theft Auto: San Andreas.[33] Rockstar president Sam Houser felt that following up San Andreas was "a nightmare".[34] Rockstar North, the core 220-person team behind the game, co-opted studios owned by parent company Rockstar Games to facilitate development between a full team of over 1,000,[35] including 50 employees at Rockstar NYC, 40 at Rockstar Lincoln, 10 at Rockstar San Diego, and around 600–700 working part-time internally and externally.[36] Some key members of the development team worked 12-hour days during production, often without holidays.[35] The team decided to continue the numbering scheme absent from the previous two main games to represent the same leap in production as Grand Theft Auto 2 (1999) to Grand Theft Auto III (2001).[33] Development of Grand Theft Auto IV ceased by 21 April 2008 when the game was submitted for manufacturing.[37] Producer Leslie Benzies estimated that the budget of the development efforts exceeded US$100 million, making Grand Theft Auto IV one of the most expensive video games ever made.[35]
Research and open world design[edit]
The game's setting, Liberty City, is based on New York City. The team did not look at the previous renditions of Liberty City as inspiration, wanting it to retain the "general feel" but nothing else.[38] The map is roughly three times the size of Grand Theft Auto III's.[38] The developers originally considered using the entire state of New York, before restricting it to Manhattan, and then expanding it out again. They considered including more suburbs with woods, and would regularly vote on which areas to include.[39] Art director Aaron Garbut said that the team chose the setting because of the detail and variety it provided, describing New York as "an amazing, diverse, vibrant, cinematic city".[40] Writer Dan Houser added that the team "wanted to be somewhere where we had a foothold" due to the amount of research required for the world; Rockstar Games's main headquarters are located in New York.[41] The team consciously avoided a precise recreation of New York City to allow for more enjoyable game design,[32] selecting the areas that they felt "characterised it the best".[40] Garbut wanted to capture a caricature of the city as he felt that most people were familiar with "the highlights" from film or literature but did not need to know the areas precisely.[40] The city was not built with specific missions in mind; the area was created first, and missions implemented later.[42]
To achieve a realistic environment, 60–70 employees from Rockstar North travelled to New York for research: first at the beginning of the project in March or April 2005 for a week and a half,[39] and a smaller trip in 2007.[38] Police officers who previously worked the beat drove the team around Washington Heights.[39] A full-time research team based in New York handled further requests for information, such as the ethnic minority of a neighbourhood or videos of traffic patterns. Videos shot in New York were played on televisions at the Rockstar North offices "so while they worked they could look up and there was New York".[39] Benzies claimed that the team took over 100,000 photographs on location in New York,[35] though Garbut estimates that they took around 250,000.[38] They also studied architectural plans for apartments, used satellite images to determine city block layout, researched sales figures for models of cars, and read books that detailed the city's infrastructure, including its subways, sewers, and garbage disposal.[43] Hove Beach is based on Brighton Beach, which Sam Houser found "pretty incredible" and unusual; the name is based on the English city Brighton and Hove, made up of the former neighbouring towns Brighton and Hove.[44] Houser appreciated that Brighton Beach was home to several Eastern Europeans due to the nature of the game's characters.[44]
Dan Houser described Liberty City as "the biggest character" of the game.[40] The Grand Theft Auto IV rendition of Liberty City is more detailed and larger in size than most earlier entries in the series; although smaller than San Andreas, the setting of the previous main game, the developers considered it comparable in scope due to city's verticality, number of buildings, and level of detail.[45] The team wanted less dead spots and irrelevant spaces, such as the wide open deserts in San Andreas.[32] They wanted the game to be "a more focused experience" than San Andreas, and Dan Houser felt that the limited activities of New York allowed this.[33] The team felt that the addition of Niko's mobile phone added to the immersion of the world and represented society's shifted focus on phones.[33] The in-game brands and products are designed over several years; the billboards were implemented in the game around six months prior to release.[38]
Story and character development[edit]
The game's script, written by Dan Houser and Rupert Humphries, is about 1,000 pages.[35] Approximately 660 actors provided voices for the game over 80,000 lines of dialogue.[39] After conceiving the character and setting, Dan Houser spoke with his brother Sam Houser and Leslie Benzies to bounce story ideas before writing a rough synopsis, a six-paged, detailed document. Once the synopsis was reworked, the designers broke it into missions, represented by a large flow document demonstrating each section. The writers then work on the introductions to the missions; the gameplay dialogue comes much later.[41] Unlike previous Grand Theft Auto games, Grand Theft Auto IV does not have cinematic influences. "We were consciously trying to go, well, if video games are going to develop into the next stage, then the thing isn't to try and do a loving tribute or reference other stuff," said Dan Houser.[41] He said that the writers wanted something "fresh and new and not something that was obviously derived from [a] movie".[41] Dan Houser felt that the quality of the writing had to improve alongside the advancements in graphics and technology. He noted that the improvements in facial animation allowed for slower-paced cutscenes.[40] The unique dialogue that plays when a mission is retried was to ensure that the gameplay felt "less canned and less like Groundhog Day".[40]
Dan Houser described Niko Bellic as "a more rounded character" than those in previous games.[40] He felt that his dual personality—often saving innocent people, while also being a "cold-hearted killer"—made him more relatable.[40] He also felt that Niko's unfamiliarity with Liberty City allowed for the player to relate to him more, only driven by his vague past and relationship with Roman. When deciding on Niko's background, the writers felt that being an immigrant could lead to more dangerous situations, and therefore more enjoyable missions; after discussions with criminal experts, Dan Houser found that "the real scary characters are not born in America anymore".[40] He felt that Niko's outsider view of American culture was "fun".[40] The team wanted Niko to be "more of an anti hero than a hero, capable of making positive actions within his criminal world".[46] They wanted his demeanour to reflect the weight of his past and choices.[46]
Niko's design underwent a few changes, but was finalised early in development.[47] His outfit underwent several changes based on Eastern Europeans, particularly photographs of men fighting in winter wars in Yugoslavia and Chechnya. The primary motivation for the design was a face to convey the appropriate emotions and a body that could move nicely with the new animations.[40] The in-game purchasable outfits were also designed to fit with the character.[33] The team ensured that the gameplay choices presented to the player were not too extensive, as they still had to make sense to the character, who is driven by the people around him. Dan Houser felt that the missions in San Andreas had become too linear, and wanted to present choices to the player in Grand Theft Auto IV.[40]
The writers found that Niko needed a motivation to come to America, so they created his cousin, Roman. Dan Houser felt that the two could not be brothers as there would be a deeper level of familiarity than necessary. He described the two as a double act, with Roman's fantasist charm playing off Niko's tough cynicism. The team gave other non-playable characters (NPCs) more definable behaviours and dialogue to make them feel more alive. The writers initially considered having a smaller group of characters, but found that the story became boring and that players were less likely to explore the world. The stranger characters found in the game world were based on the "crazy people" that populate New York, according to Dan Houser, which in previous games were only able to be captured through radio stations or mild pedestrian behaviours.[38] The team based the ethnicities, clothing, and behaviours of the NPCs on the photographs and videos that they captured around New York, divided into different areas;[40] they created mood boards for each location.[38] The NPCs also converse in different languages.[39]
Art design[edit]
Grand Theft Auto IV sees a shift in the series to a more realistic and detailed style and tone, partly a result of the transition to consoles which offered high-definition graphics and the new and improved capabilities of such consoles. The development team worked to represent the upgrade in quality across all design aspects while maintaining the coherence of the previous games.[32] The team took the game's development as an opportunity to "strip things back and start again", refining the art style without losing the style of the series;[40] they distanced the game from the "cartoon-like style" of its predecessors while creating a new style that was consistent across all aspects of the game.[48] Garbut found the increased demand of detail brought on by the advanced technology daunting.[49] A technique used to make the visuals look real was to avoid harsh edges, instead blending surfaces together to make the world look dirty and lived-in.[50] The props department created multiple variations of different objects to make the world more interesting and unique.[40] G
Animal
Animal theme by Tony (gaara1978)
Download: Animal.p3t
(9 backgrounds)
| Animals Temporal range: Cryogenian – present,
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Scientific classification 
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| Domain: | Eukaryota |
| Clade: | Amorphea |
| Clade: | Obazoa |
| (unranked): | Opisthokonta |
| (unranked): | Holozoa |
| (unranked): | Filozoa |
| Clade: | Choanozoa |
| Kingdom: | Animalia Linnaeus, 1758 |
| Subdivisions | |
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| Synonyms | |
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ˌænɪˈmɑːliə/[4]). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor.
Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft). They have complex ecologies and interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology, and the study of animal behaviors is known as ethology.
Most living animal species belong to the infrakingdom Bilateria, a highly proliferative clade whose members have a bilaterally symmetric body plan. The vast majority belong to two large superphyla: the protostomes, which includes organisms such as the arthropods, molluscs, flatworms, annelids and nematodes; and the deuterostomes, which include the echinoderms, hemichordates and chordates, the latter of which contains the vertebrates. The simple Xenacoelomorpha have an uncertain position within Bilateria.
Animals first appear in the fossil record in the late Cryogenian period, and diversified in the subsequent Ediacaran. Earlier evidence of animals is still controversial; the sponge-like organism Otavia has been dated back to the Tonian period at the start of the Neoproterozoic, but its identity as an animal is heavily contested.[5] Nearly all modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period.
Historically, Aristotle divided animals into those with blood and 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 (now synonymous with Animalia) 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 taxa.
Humans make use of many other animal species for food (including meat, eggs, and dairy products), for materials (such as leather, fur, and wool), as pets and as working animals for transportation, and services. Dogs, the first domesticated animal, have been used in hunting, in security and in warfare, as have horses, pigeons and birds of prey; while other terrestrial and aquatic animals are hunted for sports, trophies or profits. Non-human animals are also an important cultural element of human evolution, having appeared in cave arts and totems since the earliest times, and are frequently featured in mythology, religion, arts, literature, heraldry, politics, and sports.
Etymology[edit]
The word animal comes from the Latin noun animal of the same meaning, which is itself derived from Latin animalis 'having breath or soul'.[6] The biological definition includes all members of the kingdom Animalia.[7] In colloquial usage, the term animal is often used to refer only to nonhuman animals.[8][9][10][11] The term metazoa is derived from Ancient Greek μετα (meta) 'after' (in biology, the prefix meta- stands for 'later') and ζῷᾰ (zōia) 'animals', plural of ζῷον zōion 'animal'.[12][13]
Characteristics[edit]
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular.[14] Unlike plants and algae, which produce their own nutrients,[15] animals are heterotrophic,[16][17] feeding on organic material and digesting it internally.[18] With very few exceptions, animals respire aerobically.[a][20] All animals are motile[21] (able to spontaneously move their bodies) during at least part of their life cycle, but some animals, such as sponges, corals, mussels, and barnacles, later become sessile. The blastula is a stage in embryonic development that is unique to animals, allowing cells to be differentiated into specialised tissues and organs.[22]
Structure[edit]
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins.[23] During development, the animal extracellular matrix forms a relatively 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, bones, and spicules.[24] In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth.[25] Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.[26]
With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues.[27] These include muscles, which enable locomotion, and nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal digestive chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians).[28]
Reproduction and development[edit]
Nearly all animals make use of some form of sexual reproduction.[29] They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova.[30] These fuse to form zygotes,[31] which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge.[32] In most other groups, the blastula undergoes more complicated rearrangement.[33] It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm.[34] In most cases, a third germ layer, the mesoderm, also develops between them.[35] These germ layers then differentiate to form tissues and organs.[36]
Repeated instances of mating with a close relative during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits.[37][38] Animals have evolved numerous mechanisms for avoiding close inbreeding.[39]
Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids.[40][41]
Ecology[edit]
_Naggar,_Himachal_Pradesh,_2013_(cropped).JPG)
Animals are categorised into ecological groups depending on their trophic levels and how they consume organic material. Such groupings include carnivores (further divided into subcategories such as piscivores, insectivores, ovivores, etc.), herbivores (subcategorized into folivores, graminivores, frugivores, granivores, nectarivores, algivores, etc.), omnivores, fungivores, scavengers/detritivores,[42] and parasites.[43] Interactions between animals of each biome form complex food webs within that ecosystem. In carnivorous or omnivorous species, predation is a consumer–resource interaction where the predator feeds on another organism, its prey,[44] who often evolves anti-predator adaptations to avoid being fed upon. Selective pressures imposed on one another lead to an evolutionary arms race between predator and prey, resulting in various antagonistic/competitive coevolutions.[45][46] Almost all multicellular predators are animals.[47] Some consumers use multiple methods; for example, in parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process,[48] but the adults primarily consume nectar from flowers.[49] Other animals may have very specific feeding behaviours, such as hawksbill sea turtles which mainly eat sponges.[50]
Most animals rely on biomass and bioenergy produced by plants and phytoplanktons (collectively called producers) through photosynthesis. Herbivores, as primary consumers, eat the plant material directly to digest and absorb the nutrients, while carnivores and other animals on higher trophic levels indirectly acquire the nutrients by eating the herbivores or other animals that have eaten the herbivores. Animals oxidize carbohydrates, lipids, proteins and other biomolecules, which allows the animal to grow and to sustain basal metabolism and fuel other biological processes such as locomotion.[51][52][53] Some benthic animals living close to hydrothermal vents and cold seeps on the dark sea floor consume organic matter produced through chemosynthesis (via oxidizing inorganic compounds such as hydrogen sulfide) by archaea and bacteria.[54]
Animals evolved in the sea. Lineages of arthropods colonised land around the same time as land plants, probably between 510 and 471 million years ago during the Late Cambrian or Early Ordovician.[55] Vertebrates such as the lobe-finned fish Tiktaalik started to move on to land in the late Devonian, about 375 million years ago.[56][57] Animals occupy virtually all of earth's habitats and microhabitats, with faunas adapted to salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of other organisms.[58] Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F)[59] or in the most extreme cold deserts of continental Antarctica.[60]
Diversity[edit]
Size[edit]
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The blue whale (Balaenoptera musculus) is the largest animal that has ever lived, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long.[61][62][63] The largest extant terrestrial animal is the African bush elephant (Loxodonta africana), weighing up to 12.25 tonnes[61] and measuring up to 10.67 metres (35.0 ft) long.[61] The largest terrestrial animals that ever lived were titanosaur sauropod dinosaurs such as Argentinosaurus, which may have weighed as much as 73 tonnes, and Supersaurus which may have reached 39 meters.[64][65] Several animals are microscopic; some Myxozoa (obligate parasites within the Cnidaria) never grow larger than 20 μm,[66] and one of the smallest species (Myxobolus shekel) is no more than 8.5 μm when fully grown.[67]
Numbers and habitats of major phyla[edit]
The following table lists estimated numbers of described extant species for the major animal phyla,[68] along with their principal habitats (terrestrial, fresh water,[69] and marine),[70] and free-living or parasitic ways of life.[71] Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million.[72] Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.[73][74][b]
