Misplaced Pages

#39960

106-598: A number of factors affect the time of day an animal is active. Predators hunt when their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature may be too high at midday or too low at night. Some creatures may adjust their activities depending on local competition. The word crepuscular derives from the Latin crepusculum ("twilight"). Its sense accordingly differs from diurnal and nocturnal behavior, which respectively peak during hours of daytime and night. The distinction

212-457: A mischief . The common species are opportunistic survivors and often live with and near humans ; therefore, they are known as commensals . They may cause substantial food losses, especially in developing countries. However, the widely distributed and problematic commensal species of rats are a minority in this diverse genus. Many species of rats are island endemics , some of which have become endangered due to habitat loss or competition with

318-455: A mutation (the deletion of two nucleotides ) that inactives it. These changes are explained by the fact that its prey does not need to be subdued. Several groups of predatory fish have the ability to detect, track, and sometimes, as in the electric ray , to incapacitate their prey by sensing and generating electric fields . The electric organ is derived from modified nerve or muscle tissue. Physiological adaptations to predation include

424-418: A better choice. If it chooses pursuit, its physical capabilities determine the mode of pursuit (e.g., ambush or chase). Having captured the prey, it may also need to expend energy handling it (e.g., killing it, removing any shell or spines, and ingesting it). Predators have a choice of search modes ranging from sit-and-wait to active or widely foraging . The sit-and-wait method is most suitable if

530-851: A broad range of taxa including arthropods. They are common among insects, including mantids, dragonflies , lacewings and scorpionflies . In some species such as the alderfly , only the larvae are predatory (the adults do not eat). Spiders are predatory, as well as other terrestrial invertebrates such as scorpions ; centipedes ; some mites , snails and slugs ; nematodes ; and planarian worms . In marine environments, most cnidarians (e.g., jellyfish , hydroids ), ctenophora (comb jellies), echinoderms (e.g., sea stars , sea urchins , sand dollars , and sea cucumbers ) and flatworms are predatory. Among crustaceans , lobsters , crabs , shrimps and barnacles are predators, and in turn crustaceans are preyed on by nearly all cephalopods (including octopuses , squid and cuttlefish ). Seed predation

636-509: A deterrent simply by their presence. Rats have the ability to swim up sewer pipes into toilets. Rats will infest any area that provides shelter and easy access to sources of food and water, including under sinks, near garbage, and inside walls or cabinets. Rats can serve as zoonotic vectors for certain pathogens and thus spread disease, such as bubonic plague , Lassa fever , leptospirosis , and Hantavirus infection. Researchers studying New York City wastewater have also cited rats as

742-617: A dozen diseases directly linked to rats. Most urban areas battle rat infestations. A 2015 study by the American Housing Survey (AHS) found that eighteen percent of homes in Philadelphia showed evidence of rodents. Boston , New York City , and Washington, D.C. , also demonstrated significant rodent infestations. Indeed, rats in New York City are famous for their size and prevalence. The urban legend that

848-582: A food trap, mechanical stimulation, and electrical impulses to eventually catch and consume its prey. Some carnivorous fungi catch nematodes using either active traps in the form of constricting rings, or passive traps with adhesive structures. Many species of protozoa ( eukaryotes ) and bacteria ( prokaryotes ) prey on other microorganisms; the feeding mode is evidently ancient, and evolved many times in both groups. Among freshwater and marine zooplankton , whether single-celled or multi-cellular, predatory grazing on phytoplankton and smaller zooplankton

954-477: A huge gulp of water and filtering it through their feathery baleen plates. Pursuit predators may be social , like the lion and wolf that hunt in groups, or solitary. Once the predator has captured the prey, it has to handle it: very carefully if the prey is dangerous to eat, such as if it possesses sharp or poisonous spines, as in many prey fish. Some catfish such as the Ictaluridae have spines on

1060-725: A kill, and the coyote can be either solitary or social. Other solitary predators include the northern pike, wolf spiders and all the thousands of species of solitary wasps among arthropods, and many microorganisms and zooplankton . Under the pressure of natural selection , predators have evolved a variety of physical adaptations for detecting, catching, killing, and digesting prey. These include speed, agility, stealth, sharp senses, claws, teeth, filters, and suitable digestive systems. For detecting prey , predators have well-developed vision , smell , or hearing . Predators as diverse as owls and jumping spiders have forward-facing eyes, providing accurate binocular vision over

1166-539: A long distance, sometimes for hours at a time. The method is used by human hunter-gatherers and by canids such as African wild dogs and domestic hounds. The African wild dog is an extreme persistence predator, tiring out individual prey by following them for many miles at relatively low speed. A specialised form of pursuit predation is the lunge feeding of baleen whales . These very large marine predators feed on plankton , especially krill , diving and actively swimming into concentrations of plankton, and then taking

SECTION 10

#1732784048040

1272-534: A minimum. The effectiveness has been aided by a similar but newer program in Saskatchewan which prevents rats from even reaching the Alberta border. Alberta still employs an armed rat patrol to control rats along Alberta's borders. About ten single rats are found and killed per year, and occasionally a large localized infestation has to be dug out with heavy machinery, but the number of permanent rat infestations

1378-667: A modern myth, the rat flood in India occurs every fifty years, as armies of bamboo rats descend upon rural areas and devour everything in their path. Rats have long been held up as the chief villain in the spread of the Bubonic Plague ; however, recent studies show that rats alone could not account for the rapid spread of the disease through Europe in the Middle Ages . Still, the Centers for Disease Control does list nearly

1484-445: A new area, they quickly reproduce to take advantage of the new food supply. In particular, they prey on the eggs and young of forest birds, which on isolated islands often have no other predators and thus have no fear of predators . Some experts believe that rats are to blame for between forty percent and sixty percent of all seabird and reptile extinctions, with ninety percent of those occurring on islands. Thus man has indirectly caused

1590-445: A patch and decide whether to spend time searching for prey in it. This may involve some knowledge of the preferences of the prey; for example, ladybirds can choose a patch of vegetation suitable for their aphid prey. To capture prey, predators have a spectrum of pursuit modes that range from overt chase ( pursuit predation ) to a sudden strike on nearby prey ( ambush predation ). Another strategy in between ambush and pursuit

1696-603: A popular choice due to their high intelligence, ingenuity, aggressiveness , and adaptability . Their psychology seems in many ways similar to that of humans. Inspired by B.F. Skinner ’s famous box which dispensed food pellets when rats pushed a lever, photographer Augustin Lignier gave two rats periodic, unpredictable rewards for pressing a button. He likened their repeated button-pressing behaviors to people’s fascinations with digital and social media. Early studies found evidence both for and against measurable intelligence using

1802-425: A powerful selective effect on prey, and the prey develop antipredator adaptations such as warning coloration , alarm calls and other signals , camouflage , mimicry of well-defended species, and defensive spines and chemicals. Sometimes predator and prey find themselves in an evolutionary arms race , a cycle of adaptations and counter-adaptations. Predation has been a major driver of evolution since at least

1908-785: A predator, while small prey might prove hard to find and in any case provide less of a reward. This has led to a correlation between the size of predators and their prey. Size may also act as a refuge for large prey. For example, adult elephants are relatively safe from predation by lions, but juveniles are vulnerable. Members of the cat family such as the snow leopard (treeless highlands), tiger (grassy plains, reed swamps), ocelot (forest), fishing cat (waterside thickets), and lion (open plains) are camouflaged with coloration and disruptive patterns suiting their habitats. In aggressive mimicry , certain predators, including insects and fishes, make use of coloration and behaviour to attract prey. Female Photuris fireflies , for example, copy

2014-421: A preferred target is scarce. When prey have a clumped (uneven) distribution, the optimal strategy for the predator is predicted to be more specialized as the prey are more conspicuous and can be found more quickly; this appears to be correct for predators of immobile prey, but is doubtful with mobile prey. In size-selective predation, predators select prey of a certain size. Large prey may prove troublesome for

2120-462: A province in 1905. Black rats cannot survive in its climate at all, and brown rats must live near people and in their structures to survive the winters. There are numerous predators in Canada's vast natural areas which will eat non-native rats, so it took until 1950 for invading rats to make their way over land from Eastern Canada. Immediately upon their arrival at the eastern border with Saskatchewan ,

2226-556: A quick temper and wastefulness. People born in a year of the rat are said to get along well with "monkeys" and "dragons", and to get along poorly with "horses". In Indian tradition, rats are seen as the vehicle of Ganesha , and a rat's statue is always found in a temple of Ganesh. In the northwestern Indian city of Deshnoke , the rats at the Karni Mata Temple are held to be destined for reincarnation as Sadhus ( Hindu holy men). The attending priests feed milk and grain to

SECTION 20

#1732784048040

2332-820: A relatively narrow field of view, whereas prey animals often have less acute all-round vision. Animals such as foxes can smell their prey even when it is concealed under 2 feet (60 cm) of snow or earth. Many predators have acute hearing, and some such as echolocating bats hunt exclusively by active or passive use of sound. Predators including big cats , birds of prey , and ants share powerful jaws, sharp teeth, or claws which they use to seize and kill their prey. Some predators such as snakes and fish-eating birds like herons and cormorants swallow their prey whole; some snakes can unhinge their jaws to allow them to swallow large prey, while fish-eating birds have long spear-like beaks that they use to stab and grip fast-moving and slippery prey. Fish and other predators have developed

2438-478: A significant amount of energy, to locate each food patch. For example, the black-browed albatross regularly makes foraging flights to a range of around 700 kilometres (430 miles), up to a maximum foraging range of 3,000 kilometres (1,860 miles) for breeding birds gathering food for their young. With static prey, some predators can learn suitable patch locations and return to them at intervals to feed. The optimal foraging strategy for search has been modelled using

2544-406: A small animal, gulping the prey in an extremely rapid movement when it is within range. Many smaller predators such as the box jellyfish use venom to subdue their prey, and venom can also aid in digestion (as is the case for rattlesnakes and some spiders ). The marbled sea snake that has adapted to egg predation has atrophied venom glands, and the gene for its three finger toxin contains

2650-523: A smaller area. For example, when mixed flocks of birds forage, the birds in front flush out insects that are caught by the birds behind. Spinner dolphins form a circle around a school of fish and move inwards, concentrating the fish by a factor of 200. By hunting socially chimpanzees can catch colobus monkeys that would readily escape an individual hunter, while cooperating Harris hawks can trap rabbits. Predators of different species sometimes cooperate to catch prey. In coral reefs , when fish such as

2756-410: A state of proprioceptive balance in its environment. Further mechanobiological investigations of the constituent tendons in the tail of the rat have identified multiple factors that influence how the organism navigates its environment with this structure. A particular example is that of a study in which the morphology of these tendons is explicated in detail. Namely, cell viability tests of tendons of

2862-653: A successful trial on the smaller Hawea Island nearby. In January 2015, an international "Rat Team" set sail from the Falkland Islands for the British Overseas Territory of South Georgia and the South Sandwich Islands on board a ship carrying three helicopters and 100 tons of rat poison with the objective of "reclaiming the island for its seabirds". Rats have wiped out more than 90% of the seabirds on South Georgia, and

2968-415: A thermoregulation function that follows from its anatomical construction. This particular tail morphology is evident across the family Muridae, in contrast to the bushier tails of Sciuridae , the squirrel family. The tail is hairless and thin skinned but highly vascularized, thus allowing for efficient countercurrent heat exchange with the environment. The high muscular and connective tissue densities of

3074-428: A unique defense mechanism known as degloving in which the outer layer of the integument can be detached in order to facilitate the animal's escape from a predator. This evolutionary selective pressure has persisted despite a multitude of pathologies that can manifest upon shedding part of the tail and exposing more interior elements to the environment. Paramount among these are bacterial and viral infection, as

3180-440: A variety of defences including the ability to hear the echolocation calls. Many pursuit predators that run on land, such as wolves, have evolved long limbs in response to the increased speed of their prey. Their adaptations have been characterized as an evolutionary arms race , an example of the coevolution of two species. In a gene centered view of evolution , the genes of predator and prey can be thought of as competing for

3286-477: Is ballistic interception , where a predator observes and predicts a prey's motion and then launches its attack accordingly. Ambush or sit-and-wait predators are carnivorous animals that capture prey by stealth or surprise. In animals, ambush predation is characterized by the predator's scanning the environment from a concealed position until a prey is spotted, and then rapidly executing a fixed surprise attack. Vertebrate ambush predators include frogs, fish such as

Crepuscular animal - Misplaced Pages Continue

3392-577: Is a biological interaction where one organism, the predator , kills and eats another organism, its prey . It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host ) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge ; it overlaps with herbivory , as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey

3498-494: Is common, and found in many species of nanoflagellates , dinoflagellates , ciliates , rotifers , a diverse range of meroplankton animal larvae, and two groups of crustaceans, namely copepods and cladocerans . To feed, a predator must search for, pursue and kill its prey. These actions form a foraging cycle. The predator must decide where to look for prey based on its geographical distribution; and once it has located prey, it must assess whether to pursue it or to wait for

3604-629: Is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation , sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision , hearing , or smell . Many predatory animals , both vertebrate and invertebrate , have sharp claws or jaws to grip, kill, and cut up their prey. Other adaptations include stealth and aggressive mimicry that improve hunting efficiency. Predation has

3710-578: Is normally active during the day, but on islands like Santa Cruz that are home to the Galapagos hawk , the owl is crepuscular. Apart from the relevance to predation, crepuscular activity in hot regions also may be the most effective way of avoiding heat stress while capitalizing on available light. Crepuscular flight activity is preferred by some animals, such as the walnut twig beetle , due to warmer temperatures, moderate wind speeds, and low barometric pressure. Crepuscular activity can be influenced by

3816-725: Is not absolute, because crepuscular animals may also be active on a bright moonlit night or on a dull day. Some animals casually described as nocturnal are in fact crepuscular. Special classes of crepuscular behaviour include matutinal, or "matinal", animals active only in the dawn, and vespertine, only in the dusk. Those active during both times are said to have a bimodal activity pattern. The various patterns of activity are thought to be mainly antipredator adaptations , though some could equally well be predatory adaptations . Many predators forage most intensively at night, whereas others are active at midday and see best in full sun. The crepuscular habit may both reduce predation pressure, increasing

3922-466: Is notable for being the largest inhabited area on Earth which is free of true rats due to very aggressive government rat control policies. It has large numbers of native pack rats , also called bushy-tailed wood rats, but they are forest-dwelling vegetarians which are much less destructive than true rats. Alberta was settled by Europeans relatively late in North American history and only became

4028-518: Is restricted to mammals, birds, and insects but is found in almost all terrestrial ecosystems. Egg predation includes both specialist egg predators such as some colubrid snakes and generalists such as foxes and badgers that opportunistically take eggs when they find them. Some plants, like the pitcher plant , the Venus fly trap and the sundew , are carnivorous and consume insects . Methods of predation by plants varies greatly but often involves

4134-430: Is size. Prey that is too small may not be worth the trouble for the amount of energy it provides. Too large, and it may be too difficult to capture. For example, a mantid captures prey with its forelegs and they are optimized for grabbing prey of a certain size. Mantids are reluctant to attack prey that is far from that size. There is a positive correlation between the size of a predator and its prey. A predator may assess

4240-484: Is subject to special measures and regularly monitored for rat invasions. As part of island restoration , some islands' rat populations have been eradicated to protect or restore the ecology . Hawadax Island, Alaska was declared rat free after 229 years and Campbell Island, New Zealand after almost 200 years. Breaksea Island in New Zealand was declared rat free in 1988 after an eradication campaign based on

4346-621: Is zero. Ancient Romans did not generally differentiate between rats and mice, instead referring to the former as mus maximus (big mouse) and the latter as mus minimus (little mouse). On the Isle of Man , there is a taboo against the word " rat ". The rat (sometimes referred to as a mouse) is the first of the twelve animals of the Chinese zodiac . People born in this year are expected to possess qualities associated with rats, including creativity, intelligence, honesty, generosity, ambition,

Crepuscular animal - Misplaced Pages Continue

4452-510: The "g factor" in rats. Part of the difficulty of understanding animal cognition , generally, is determining what to measure. One aspect of intelligence is the ability to learn, which can be measured using a maze like the T-maze . Experiments done in the 1920s showed that some rats performed better than others in maze tests, and if these rats were selectively bred, their offspring also performed better, suggesting that in rats an ability to learn

4558-456: The Cambrian period. At the most basic level, predators kill and eat other organisms. However, the concept of predation is broad, defined differently in different contexts, and includes a wide variety of feeding methods; moreover, some relationships that result in the prey's death are not necessarily called predation. A parasitoid , such as an ichneumon wasp , lays its eggs in or on its host;

4664-465: The angel shark , the northern pike and the eastern frogfish . Among the many invertebrate ambush predators are trapdoor spiders and Australian Crab spiders on land and mantis shrimps in the sea. Ambush predators often construct a burrow in which to hide, improving concealment at the cost of reducing their field of vision. Some ambush predators also use lures to attract prey within striking range. The capturing movement has to be rapid to trap

4770-566: The aortic branches . Aortic arches studied in rats exhibit abnormalities similar to those of humans, including altered pulmonary arteries and double or absent aortic arches. Despite existing anatomical analogy in the inthrathoracic position of the heart itself, the murine model of the heart and its structures remains a valuable tool for studies of human cardiovascular conditions. The rat's larynx has been used in experimentations that involve inhalation toxicity, allograft rejection, and irradiation responses. One experiment described four features of

4876-415: The brown rat or wharf rat , has also been carried worldwide by ships in recent centuries. The ship or wharf rat has contributed to the extinction of many species of wildlife, including birds, small mammals, reptiles, invertebrates, and plants, especially on islands. True rats are omnivorous , capable of eating a wide range of plant and animal foods, and have a very high birth rate . When introduced to

4982-455: The common garter snake has developed a resistance to the toxin in the skin of the rough-skinned newt . Predators affect their ecosystems not only directly by eating their own prey, but by indirect means such as reducing predation by other species, or altering the foraging behaviour of a herbivore, as with the biodiversity effect of wolves on riverside vegetation or sea otters on kelp forests. This may explain population dynamics effects such as

5088-420: The common nighthawk , barn owl , owlet-nightjar , chimney swift , American woodcock , spotted crake , white-breasted waterhen , European nightjars , and common buzzards . Many moths , beetles , flies , and other insects are crepuscular and vespertine. For example, Coprophanaeus ensifer , a South American necrophagous beetle, is most active during at dusk and dawn. Predation Predation

5194-475: The grouper and coral trout spot prey that is inaccessible to them, they signal to giant moray eels , Napoleon wrasses or octopuses . These predators are able to access small crevices and flush out the prey. Killer whales have been known to help whalers hunt baleen whales . Social hunting allows predators to tackle a wider range of prey, but at the risk of competition for the captured food. Solitary predators have more chance of eating what they catch, at

5300-400: The lunar cycle due to the change in nocturnal light. This creates changes in animal sleep , reproduction , and foraging behaviours, often becoming less active during periods of low light. Animal patterns of activity sometimes change during migration due to changes in environmental conditions. Mule deer are crepuscular, but they are only active at dusk before and during migration. In

5406-465: The marginal value theorem . Search patterns often appear random. One such is the Lévy walk , that tends to involve clusters of short steps with occasional long steps. It is a good fit to the behaviour of a wide variety of organisms including bacteria, honeybees, sharks and human hunter-gatherers. Having found prey, a predator must decide whether to pursue it or keep searching. The decision depends on

SECTION 50

#1732784048040

5512-611: The spring they are only active at dawn because the snow is at its hardest , so it is easier for the deer to move without sinking in the snow. During migration, some types of swallow are active primarily during daytime hours with some activity during twilight hours. Crepuscular animal activity is affected by human activity , because humans are diurnal. Crepuscular animals are less likely to participate in typical foraging or reproductive behaviors and deal with increased stress and mortality rates when humans are present. Animals may change their usual activity patterns in response to

5618-520: The Alberta government implemented an extremely aggressive rat control program to stop them from advancing further. A systematic detection and eradication system was used throughout a control zone about 600 kilometres (400 mi) long and 30 kilometres (20 mi) wide along the eastern border to eliminate rat infestations before the rats could spread further into the province. Shotguns, bulldozers, high explosives, poison gas, and incendiaries were used to destroy rats. Numerous farm buildings were destroyed in

5724-411: The North American pack rats (aka wood rats ) and a number of species loosely called kangaroo rats . Rats such as the bandicoot rat ( Bandicota bengalensis ) are murine rodents related to true rats but are not members of the genus Rattus . Male rats are called bucks ; unmated females, does , pregnant or parent females, dams ; and infants, kittens or pups . A group of rats is referred to as

5830-709: The ability of predatory bacteria to digest the complex peptidoglycan polymer from the cell walls of the bacteria that they prey upon. Carnivorous vertebrates of all five major classes (fishes, amphibians, reptiles, birds, and mammals) have lower relative rates of sugar to amino acid transport than either herbivores or omnivores, presumably because they acquire plenty of amino acids from the animal proteins in their diet. To counter predation, prey have evolved defences for use at each stage of an attack. They can try to avoid detection, such as by using camouflage and mimicry . They can detect predators and warn others of their presence. If detected, they can try to avoid being

5936-733: The ability to crush or open the armoured shells of molluscs. Many predators are powerfully built and can catch and kill animals larger than themselves; this applies as much to small predators such as ants and shrews as to big and visibly muscular carnivores like the cougar and lion . Predators are often highly specialized in their diet and hunting behaviour; for example, the Eurasian lynx only hunts small ungulates . Others such as leopards are more opportunistic generalists, preying on at least 100 species. The specialists may be highly adapted to capturing their preferred prey, whereas generalists may be better able to switch to other prey when

6042-584: The assault. When animals eat seeds ( seed predation or granivory ) or eggs ( egg predation ), they are consuming entire living organisms, which by definition makes them predators. Scavengers , organisms that only eat organisms found already dead, are not predators, but many predators such as the jackal and the hyena scavenge when the opportunity arises. Among invertebrates, social wasps such as yellowjackets are both hunters and scavengers of other insects. While examples of predators among mammals and birds are well known, predators can be found in

6148-684: The back (dorsal) and belly (pectoral) which lock in the erect position; as the catfish thrashes about when captured, these could pierce the predator's mouth, possibly fatally. Some fish-eating birds like the osprey avoid the danger of spines by tearing up their prey before eating it. In social predation, a group of predators cooperates to kill prey. This makes it possible to kill creatures larger than those they could overpower singly; for example, hyenas , and wolves collaborate to catch and kill herbivores as large as buffalo, and lions even hunt elephants. It can also make prey more readily available through strategies like flushing of prey and herding it into

6254-470: The brown, black, or Polynesian rat . Wild rodents, including rats, can carry many different zoonotic pathogens, such as Leptospira , Toxoplasma gondii , and Campylobacter . The Black Death is traditionally believed to have been caused by the microorganism Yersinia pestis , carried by the tropical rat flea ( Xenopsylla cheopis ), which preyed on black rats living in European cities during

6360-621: The condition is known as rat mite dermatitis . When introduced into locations where rats previously did not exist, they can wreak an enormous degree of environmental degradation . Rattus rattus , the black rat , is considered to be one of the world's worst invasive species. Also known as the ship rat , it has been carried worldwide as a stowaway on seagoing vessels for millennia and has usually accompanied men to any new area visited or settled by human beings by sea. Rats first got to countries such as America and Australia by stowing away on ships. The similar species Rattus norvegicus ,

6466-416: The costs and benefits involved. A bird foraging for insects spends a lot of time searching but capturing and eating them is quick and easy, so the efficient strategy for the bird is to eat every palatable insect it finds. By contrast, a predator such as a lion or falcon finds its prey easily but capturing it requires a lot of effort. In that case, the predator is more selective. One of the factors to consider

SECTION 60

#1732784048040

6572-479: The crepuscular populations, and offer better foraging opportunities to predators that increasingly focus their attention on crepuscular prey until a new balance is struck. Such shifting states of balance are often found in ecology. Some predatory species adjust their habits in response to competition from other predators. For example, the subspecies of short-eared owl that lives on the Galápagos Islands

6678-738: The cycles observed in lynx and snowshoe hares. One way of classifying predators is by trophic level . Carnivores that feed on herbivores are secondary consumers; their predators are tertiary consumers, and so forth. At the top of this food chain are apex predators such as lions . Many predators however eat from multiple levels of the food chain; a carnivore may eat both secondary and tertiary consumers. This means that many predators must contend with intraguild predation , where other predators kill and eat them. For example, coyotes compete with and sometimes kill gray foxes and bobcats . Rat Rats are various medium-sized, long-tailed rodents . Species of rats are found throughout

6784-537: The dumbo rat, a popular pet choice due to their low, saucer-shaped ears. A breeding standard exists for rat fanciers wishing to breed and show their rat at a rat show. In 1895, Clark University in Worcester, Massachusetts , established a population of domestic albino brown rats to study the effects of diet and for other physiological studies. Over the years, rats have been used in many experimental studies, adding to our understanding of genetics , diseases ,

6890-493: The effects of drugs , and other topics that have provided a great benefit for the health and wellbeing of humankind. The aortic arches of the rat are among the most commonly studied in murine models due to marked anatomical homology to the human cardiovascular system . Both rat and human aortic arches exhibit subsequent branching of the brachiocephalic trunk , left common carotid artery , and left subclavian artery , as well as geometrically similar, nonplanar curvature in

6996-993: The eggs hatch into larvae, which eat the host, and it inevitably dies. Zoologists generally call this a form of parasitism , though conventionally parasites are thought not to kill their hosts. A predator can be defined to differ from a parasitoid in that it has many prey, captured over its lifetime, where a parasitoid's larva has just one, or at least has its food supply provisioned for it on just one occasion. There are other difficult and borderline cases. Micropredators are small animals that, like predators, feed entirely on other organisms; they include fleas and mosquitoes that consume blood from living animals, and aphids that consume sap from living plants. However, since they typically do not kill their hosts, they are now often thought of as parasites. Animals that graze on phytoplankton or mats of microbes are predators, as they consume and kill their food organisms, while herbivores that browse leaves are not, as their food plants usually survive

7102-553: The endangered Amazon river dolphin , some species of bats , hamsters , housecats , stray dogs , rabbits , ferrets , rats , jaguars , ocelots , bobcats , servals , strepsirrhines , red pandas , bears , deer , moose , sitatunga , capybaras , chinchillas , the common mouse , skunks , squirrels , foxes , wombats , wallabies , quolls , possums and marsupial gliders , tenrecs , and spotted hyenas . Snakes , lizards , and frogs , especially those in desert environments, may be crepuscular. Crepuscular birds include

7208-427: The epidemic outbreaks of the Middle Ages ; these rats were used as transport hosts. Another zoonotic disease linked to the rat is foot-and-mouth disease . Rats become sexually mature at age 6 weeks, but reach social maturity at about 5 to 6 months of age. The average lifespan of rats varies by species, but many only live about a year due to predation. The black and brown rats diverged from other Old World rats in

7314-404: The evolution of mimicry. Avoidance is not necessarily an evolutionary response as it is generally learned from bad experiences with prey. However, when the prey is capable of killing the predator (as can a coral snake with its venom), there is no opportunity for learning and avoidance must be inherited. Predators can also respond to dangerous prey with counter-adaptations. In western North America,

7420-676: The extinction of many species by accidentally introducing rats to new areas. Rats are found in nearly all areas of Earth which are inhabited by human beings. The only rat-free continent is Antarctica , which is too cold for rat survival outdoors, and its lack of human habitation does not provide buildings to shelter them from the weather. However, rats have been introduced to many of the islands near Antarctica, and because of their destructive effect on native flora and fauna, efforts to eradicate them are ongoing. In particular, Bird Island (just off rat-infested South Georgia Island ), where breeding seabirds could be badly affected if rats were introduced,

7526-467: The forests of Asia during the beginning of the Pleistocene . The characteristic long tail of most rodents is a feature that has been extensively studied in various rat species models, which suggest three primary functions of this structure: thermoregulation , minor proprioception , and a nocifensive -mediated degloving response. Rodent tails—particularly in rat models—have been implicated with

7632-423: The high density of vascular tissue within the tail becomes exposed upon avulsion or similar injury to the structure. The degloving response is a nocifensive response, meaning that it occurs when the animal is subjected to acute pain , such as when a predator snatches the organism by the tail. Specially bred rats have been kept as pets at least since the late 19th century. Pet rats are typically variants of

7738-431: The larvae of coccinellid beetles (ladybirds) , alternate between actively searching and scanning the environment. Prey distributions are often clumped, and predators respond by looking for patches where prey is dense and then searching within patches. Where food is found in patches, such as rare shoals of fish in a nearly empty ocean, the search stage requires the predator to travel for a substantial time, and to expend

7844-429: The light signals of other species, thereby attracting male fireflies, which they capture and eat. Flower mantises are ambush predators; camouflaged as flowers, such as orchids , they attract prey and seize it when it is close enough. Frogfishes are extremely well camouflaged, and actively lure their prey to approach using an esca , a bait on the end of a rod-like appendage on the head, which they wave gently to mimic

7950-536: The midbelly. In addition, the medial thyroarytenoid muscle were focused at the midbelly while the lateral thyroarytenoid muscle MEPs were focused at the anterior third of the belly. The fourth and final feature that was cleared up was how the MEPs were distributed in the thyroarytenoid muscle. Laboratory rats have also proved valuable in psychological studies of learning and other mental processes (Barnett 2002), as well as to understand group behavior and overcrowding (with

8056-496: The order Rodentia, but stereotypical rats are found in the genus Rattus . Other rat genera include Neotoma (pack rats), Bandicota (bandicoot rats) and Dipodomys (kangaroo rats). Rats are typically distinguished from mice by their size. Usually the common name of a large muroid rodent will include the word "rat", while a smaller muroid's name will include "mouse". The common terms rat and mouse are not taxonomically specific. There are 56 known species of rats in

8162-434: The other hand, the fitness cost of a given lost dinner is unpredictable, as the predator may quickly find better prey. In addition, most predators are generalists, which reduces the impact of a given prey adaption on a predator. Since specialization is caused by predator-prey coevolution, the rarity of specialists may imply that predator-prey arms races are rare. It is difficult to determine whether given adaptations are truly

8268-478: The potential source of "cryptic" SARS-CoV-2 lineages, due to unknown viral RNA fragments in sewage matching mutations previously shown to make SARS-CoV-2 more adept at rodent-based transmission. Rats are also associated with human dermatitis because they are frequently infested with blood feeding rodent mites such as the tropical rat mite ( Ornithonyssus bacoti ) and spiny rat mite ( Laelaps echidnina ), which will opportunistically bite and feed on humans, where

8374-412: The presence of humans. For example, Asian black bears may avoid areas with high human activity during the day, but go to these locations during twilight or nighttime hours. Light pollution impacts crepuscular behaviour because it mimics natural light conditions, leading crepuscular animals to behave as they would on nights with more moonlight. Many familiar mammal species are crepuscular, including

8480-538: The prey an opportunity to escape. Some frogs wait until snakes have begun their strike before jumping, reducing the time available to the snake to recalibrate its attack, and maximising the angular adjustment that the snake would need to make to intercept the frog in real time. Ballistic predators include insects such as dragonflies, and vertebrates such as archerfish (attacking with a jet of water), chameleons (attacking with their tongues), and some colubrid snakes . In pursuit predation, predators chase fleeing prey. If

8586-549: The prey are dense and mobile, and the predator has low energy requirements. Wide foraging expends more energy, and is used when prey is sedentary or sparsely distributed. There is a continuum of search modes with intervals between periods of movement ranging from seconds to months. Sharks, sunfish , Insectivorous birds and shrews are almost always moving while web-building spiders, aquatic invertebrates, praying mantises and kestrels rarely move. In between, plovers and other shorebirds , freshwater fish including crappies , and

8692-413: The prey flees in a straight line, capture depends only on the predator's being faster than the prey. If the prey manoeuvres by turning as it flees, the predator must react in real time to calculate and follow a new intercept path, such as by parallel navigation , as it closes on the prey. Many pursuit predators use camouflage to approach the prey as close as possible unobserved ( stalking ) before starting

8798-428: The prey's body. However, the "life-dinner" principle of Dawkins and Krebs predicts that this arms race is asymmetric: if a predator fails to catch its prey, it loses its dinner, while if it succeeds, the prey loses its life. The metaphor of an arms race implies ever-escalating advances in attack and defence. However, these adaptations come with a cost; for instance, longer legs have an increased risk of breaking, while

8904-433: The prey, given that the attack is not modifiable once launched. Ballistic interception is the strategy where a predator observes the movement of a prey, predicts its motion, works out an interception path, and then attacks the prey on that path. This differs from ambush predation in that the predator adjusts its attack according to how the prey is moving. Ballistic interception involves a brief period for planning, giving

9010-509: The price of increased expenditure of energy to catch it, and increased risk that the prey will escape. Ambush predators are often solitary to reduce the risk of becoming prey themselves. Of 245 terrestrial members of the Carnivora (the group that includes the cats, dogs, and bears), 177 are solitary; and 35 of the 37 wild cats are solitary, including the cougar and cheetah. However, the solitary cougar does allow other cougars to share in

9116-427: The process. Initially, tons of arsenic trioxide were spread around thousands of farm yards to poison rats, but soon after the program commenced the rodenticide and medical drug warfarin was introduced, which is much safer for people and more effective at killing rats than arsenic. Forceful government control measures, strong public support and enthusiastic citizen participation continue to keep rat infestations to

9222-566: The publication of the rat genome sequence, and other advances, such as the creation of a rat SNP chip , and the production of knockout rats , the laboratory rat has become a useful genetic tool, although not as popular as mice . Entirely new breeds or "lines" of brown rats, such as the Wistar rat , have been bred for use in laboratories. Much of the genome of Rattus norvegicus has been sequenced. When it comes to conducting tests related to intelligence , learning, and drug abuse , rats are

9328-414: The pursuit. Pursuit predators include terrestrial mammals such as humans, African wild dogs, spotted hyenas and wolves; marine predators such as dolphins, orcas and many predatory fishes, such as tuna; predatory birds (raptors) such as falcons; and insects such as dragonflies . An extreme form of pursuit is endurance or persistence hunting , in which the predator tires out the prey by following it over

9434-475: The rat population in Manhattan equals that of its human population was definitively refuted by Robert Sullivan in his book Rats but illustrates New Yorkers' awareness of the presence, and on occasion boldness and cleverness, of the rodents. New York has specific regulations for eradicating rats; multifamily residences and commercial businesses must use a specially trained and licensed rat catcher . Chicago

9540-401: The rat's larynx. The first being the location and attachments of the thyroarytenoid muscle, the alar cricoarytenoid muscle, and the superior cricoarytenoid muscle, the other of the newly named muscle that ran from the arytenoid to a midline tubercle on the cricoid. The newly named muscles were not seen in the human larynx. In addition, the location and configuration of the laryngeal alar cartilage

9646-435: The rat's tail demonstrate a higher proportion of living fibroblasts that produce the collagen for these fibers. As in humans, these tendons contain a high density of golgi tendon organs that help the animal assess stretching of muscle in situ and adjust accordingly by relaying the information to higher cortical areas associated with balance, proprioception, and movement. The characteristic tail of murids also displays

9752-470: The result of coevolution, where a prey adaptation gives rise to a predator adaptation that is countered by further adaptation in the prey. An alternative explanation is escalation , where predators are adapting to competitors, their own predators or dangerous prey. Apparent adaptations to predation may also have arisen for other reasons and then been co-opted for attack or defence. In some of the insects preyed on by bats, hearing evolved before bats appeared and

9858-417: The specialized tongue of the chameleon, with its ability to act like a projectile, is useless for lapping water, so the chameleon must drink dew off vegetation. The "life-dinner" principle has been criticized on multiple grounds. The extent of the asymmetry in natural selection depends in part on the heritability of the adaptive traits. Also, if a predator loses enough dinners, it too will lose its life. On

9964-623: The species brown rat , but black rats and giant pouched rats are also sometimes kept. Pet rats behave differently from their wild counterparts depending on how many generations they have been kept as pets. Pet rats do not pose any more of a risk of zoonotic diseases than pets such as cats or dogs . Tamed rats are generally friendly and can be taught to perform selected behaviors. Selective breeding has brought about different color and marking varieties in rats. Genetic mutations have also created different fur types, such as rex and hairless. Congenital malformation in selective breeding have created

10070-419: The sponsors hope that once the rats are gone, it will regain its former status as home to the greatest concentration of seabirds in the world. The South Georgia Heritage Trust, which organized the mission describes it as "five times larger than any other rodent eradication attempted worldwide". That would be true if it were not for the rat control program in Alberta (see below). The Canadian province of Alberta

10176-425: The subject of investigation. Multiple studies have explored the thermoregulatory capacity of rodent tails by subjecting test organisms to varying levels of physical activity and quantifying heat conduction via the animals' tails. One study demonstrated a significant disparity in heat dissipation from a rat's tail relative to its abdomen. This observation was attributed to the higher proportion of vascularity in

10282-471: The tail's ability to function as a proprioceptive sensor and modulator has also been investigated. As aforementioned, the tail demonstrates a high degree of muscularization and subsequent innervation that ostensibly collaborate in orienting the organism. Specifically, this is accomplished by coordinated flexion and extension of tail muscles to produce slight shifts in the organism's center of mass , orientation, etc., which ultimately assists it with achieving

10388-449: The tail, along with ample muscle attachment sites along its plentiful caudal vertebrae , facilitate specific proprioceptive senses to help orient the rodent in a three-dimensional environment. Murids have evolved a unique defense mechanism termed degloving that allows for escape from predation through the loss of the outermost integumentary layer on the tail. However, this mechanism is associated with multiple pathologies that have been

10494-411: The tail, as well as its higher surface-area-to-volume ratio , which directly relates to heat's ability to dissipate via the skin. These findings were confirmed in a separate study analyzing the relationships of heat storage and mechanical efficiency in rodents that exercise in warm environments. In this study, the tail was a focal point in measuring heat accumulation and modulation. On the other hand,

10600-684: The target of an attack, for example, by signalling that they are toxic or unpalatable , by signalling that a chase would be unprofitable, or by forming groups. If they become a target, they can try to fend off the attack with defences such as armour, quills , unpalatability, or mobbing; and they can often escape an attack in progress by startling the predator, playing dead , shedding body parts such as tails, or simply fleeing. Predators and prey are natural enemies, and many of their adaptations seem designed to counter each other. For example, bats have sophisticated echolocation systems to detect insects and other prey, and insects have developed

10706-541: The work of John B. Calhoun on behavioral sink ). A 2007 study found rats to possess metacognition , a mental ability previously only documented in humans and some primates . Domestic rats differ from wild rats in many ways. They are calmer and less likely to bite; they can tolerate greater crowding; they breed earlier and produce more offspring; and their brains , livers , kidneys , adrenal glands , and hearts are smaller (Barnett 2002). Brown rats are often used as model organisms for scientific research. Since

10812-575: The world. The best-known rat species are the black rat ( Rattus rattus ) and the brown rat ( Rattus norvegicus ). This group, generally known as the Old World rats or true rats, originated in Asia . Rats are bigger than most Old World mice , which are their relatives, but seldom weigh over 500 grams ( 17 + 1 ⁄ 2  oz) in the wild. The term rat is also used in the names of other small mammals that are not true rats. Examples include

10918-461: Was declared the "rattiest city" in the US by the pest control company Orkin in 2020, for the sixth consecutive time. It's followed by Los Angeles , New York, Washington, DC, and San Francisco . To help combat the problem, a Chicago animal shelter has placed more than 1000 feral cats (sterilized and vaccinated) outside of homes and businesses since 2012, where they hunt and catch rats while also providing

11024-466: Was described. The second feature was that the way the newly named muscles appear to be familiar to those in the human larynx. The third feature was that a clear understanding of how MEPs are distributed in each of the laryngeal muscles was helpful in understanding the effects of botulinum toxin injection. The MEPs in the posterior cricoarytenoid muscle, lateral cricoarytenoid muscle, cricothyroid muscle, and superior cricoarytenoid muscle were focused mostly at

11130-694: Was heritable in some way. Rat meat is a food that, while taboo in some cultures, is a dietary staple in others. Rats have been used as working animals. Tasks for working rats include the sniffing of gunpowder residue, demining , acting and animal-assisted therapy . Rats have a keen sense of smell and are easy to train. These characteristics have been employed, for example, by the Belgian non-governmental organization APOPO , which trains rats (specifically African giant pouched rats ) to detect landmines and diagnose tuberculosis through smell. Rats have long been considered deadly pests. Once considered

11236-401: Was used to hear signals used for territorial defence and mating. Their hearing evolved in response to bat predation, but the only clear example of reciprocal adaptation in bats is stealth echolocation. A more symmetric arms race may occur when the prey are dangerous, having spines, quills, toxins or venom that can harm the predator. The predator can respond with avoidance, which in turn drives

#39960