Roadkill refers to an animal or animals that have been struck and killed by motor vehicles on highways. It has become the topic of academic research to understand the causes, how it can be mitigated; some roadkill can be eaten. During the early 20th century, roadkill or "flat meats" became a common sight in most industrialized First World nations, as they adopted the internal combustion engine and the automobile. One of the earliest observers of roadkill was the naturalist Joseph Grinnell, who noted in 1920: "This is a new source of fatality. In Europe and North America, deer are the animal most to cause vehicle damage. In Australia, specific actions taken to protect against the variety of animals that can damage vehicles – such as bullbars – indicate the Australian experience has some unique features with road kill; the development of roads affects wildlife by altering and isolating habitat and populations, deterring the movement of wildlife, resulting in extensive wildlife mortality. One writer states that "our insulated industrialized culture keeps us disconnected from life beyond our windshields."
Driving "mindlessly" without paying attention to the movements of others in the vehicle's path, driving at speeds that do not allow stopping, distractions contribute to the death toll. Moreover, a culture of indifference and hopelessness is created if people learn to ignore lifeless bodies on roads. A study in Ontario, Canada in 1996 found many reptile killed on portions of the road where vehicle tires do not pass over, which led to the inference that some drivers intentionally run over reptiles. To verify this hypothesis, research in 2007 found that 2.7% of drivers intentionally hit reptile decoys masquerading as snakes and turtles. "Indeed, several drivers were observed speeding up and positioning their vehicles to hit the reptiles". Male drivers hit the reptile decoys more than female drivers. On a more compassionate note, 3.4% of male drivers and 3% of female drivers stopped to rescue the reptile decoys. On roadways where rumble strips are installed to provide a tactile vibration alerting drivers when drifting from their lane, the rumble strips may accumulate road salt in regions where it is used.
The excess salt can attract both small and large wildlife in search of salt licks. Large numbers of mammals, reptiles and invertebrates are killed on the world's roads every day; the number of animals killed in the United States has been estimated at a million per day. About 350,000 to 27 million birds are estimated to be killed on European roads each year. Mortality resulting from roadkill can be significant for species with small populations. Roadkill is estimated to be responsible for 50% of deaths of Florida panthers, is the largest cause of badger deaths in England. Roadkill is considered to contribute to the population decline of many threatened species, including wolf and eastern quoll. In Tasmania, Australia the most common species affected by roadkill are brushtail possums and Tasmanian pademelons. In 1993, 25 schools throughout New England, United States participated in a roadkill study involving 1,923 animal deaths. By category, the fatalities were: 81% mammals, 15% bird, 3% reptiles and amphibians, 1% indiscernible.
Extrapolating these data nationwide, Merritt Clifton estimated that the following animals are being killed by motor vehicles in the United States annually: 41 million squirrels, 26 million cats, 22 million rats, 19 million opossums, 15 million raccoons, 6 million dogs, 350,000 deer. This study may not have considered differences in observability between taxa, has not been published in peer-reviewed scientific literature. A recent study showed that insects, are prone to a high risk of roadkill incidence. Research showed interesting patterns in insect roadkills in relation to the vehicle density. In 2003-2004, the Royal Society for the Protection of Birds investigated anecdotal reports of declining insect populations in the UK by asking drivers to affix a postcard-sized PVC rectangle, called a "splatometer", to the front of their cars. 40,000 drivers took part, the results found one squashed insect for every 5 miles driven. This contrasts with 30 years ago when cars were covered more with insects, supporting the idea that insect numbers had waned.
In 2011, Dutch biologist Arnold van Vliet coordinated a similar study of insect deaths on car license plates. He found two insects killed on the license-plate area for every 10 kilometres driven; this implies about 1.6 trillion insect deaths by cars per year in the Netherlands, about 32.5 trillion deaths in the United States if the figures are extrapolated there. One considered positive aspect of roadkill is the regular availability of carrion it provides for scavenger species such as vultures, foxes, Virginia opossums and a wide variety of carnivorous insects. Areas with robust scavenger populations tend to see roadkilled animal corpses being carried off, sometimes within minutes of being struck; this can cause a lower estimation of the number of roadkill animals per year. In roadkill-prone areas, scavenging birds rely on roadkill for much of their daily nutritional requirements, can be seen observing the roadway from telephone poles, overhead wires and
Domestic sheep are quadrupedal, ruminant mammals kept as livestock. Like most ruminants, sheep are members of the even-toed ungulates. Although the name sheep applies to many species in the genus Ovis, in everyday usage it always refers to Ovis aries. Numbering a little over one billion, domestic sheep are the most numerous species of sheep. An adult female sheep is referred to as a ewe, an intact male as a ram or a tup, a castrated male as a wether, a younger sheep as a lamb. Sheep are most descended from the wild mouflon of Europe and Asia. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces and milk. A sheep's wool is the most used animal fiber, is harvested by shearing. Ovine meat is called lamb when from younger animals and mutton when from older ones in Commonwealth countries, lamb in the United States. Sheep continue to be important for wool and meat today, are occasionally raised for pelts, as dairy animals, or as model organisms for science.
Sheep husbandry is practised throughout the majority of the inhabited world, has been fundamental to many civilizations. In the modern era, New Zealand, the southern and central South American nations, the British Isles are most associated with sheep production. Sheepraising has a large lexicon of unique terms which vary by region and dialect. Use of the word sheep began in Middle English as a derivation of the Old English word scēap. A group of sheep is called a herd or mob. Many other specific terms for the various life stages of sheep exist related to lambing and age. Being a key animal in the history of farming, sheep have a entrenched place in human culture, find representation in much modern language and symbology; as livestock, sheep are most associated with pastoral, Arcadian imagery. Sheep figure in many mythologies—such as the Golden Fleece—and major religions the Abrahamic traditions. In both ancient and modern religious ritual, sheep are used as sacrificial animals; the exact line of descent between domestic sheep and their wild ancestors is unclear.
The most common hypothesis states. Sheep were among the first animals to be domesticated by humankind. C in Mesopotamia; the rearing of sheep for secondary products, the resulting breed development, began in either southwest Asia or western Europe. Sheep were kept for meat and skins. Archaeological evidence from statuary found at sites in Iran suggests that selection for woolly sheep may have begun around 6000 BC, the earliest woven wool garments have been dated to two to three thousand years later. Sheep husbandry spread in Europe. Excavations show that in about 6000 BC, during the Neolithic period of prehistory, the Castelnovien people, living around Châteauneuf-les-Martigues near present-day Marseille in the south of France, were among the first in Europe to keep domestic sheep. From its inception, ancient Greek civilization relied on sheep as primary livestock, were said to name individual animals. Ancient Romans kept sheep on a wide scale, were an important agent in the spread of sheep raising.
Pliny the Elder, in his Natural History, speaks at length about wool. European colonists spread the practice to the New World from 1493 onwards. Domestic sheep are small ruminants with a crimped hair called wool and with horns forming a lateral spiral. Domestic sheep differ from their wild relatives and ancestors in several respects, having become uniquely neotenic as a result of selective breeding by humans. A few primitive breeds of sheep retain some of the characteristics of their wild cousins, such as short tails. Depending on breed, domestic sheep may have no horns at all, or horns in both sexes, or in males only. Most horned breeds have a single pair. Another trait unique to domestic sheep as compared to wild ovines is their wide variation in color. Wild sheep are variations of brown hues, variation within species is limited. Colors of domestic sheep range from pure white to dark chocolate brown, spotted or piebald. Selection for dyeable white fleeces began early in sheep domestication, as white wool is a dominant trait it spread quickly.
However, colored sheep do appear in many modern breeds, may appear as a recessive trait in white flocks. While white wool is desirable for large commercial markets, there is a niche market for colored fleeces for handspinning; the nature of the fleece varies among the breeds, from dense and crimped, to long and hairlike. There is variation of wool type and quality among members of the same flock, so wool classing is a step in the commercial processing of the fibre. Depending on breed, sheep show a range of weights, their rate of growth and mature weight is a heritable trait, selected for in breeding. Ewes weigh between 45 and 100 kilograms, rams between 45 and 160 kilograms; when all deciduous teeth have erupted, the sheep has 20 teeth. Mature sheep have 32 teeth; as with other ruminants, the front teeth in the lower jaw bite against a hard, toothless pad in the upper jaw. These are used to pick off vegetation the rear
A fungus is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separate from the other eukaryotic life kingdoms of plants and animals. A characteristic that places fungi in a different kingdom from plants and some protists is chitin in their cell walls. Similar to animals, fungi are heterotrophs. Fungi do not photosynthesize. Growth is their means of mobility, except for spores, which may travel through the water. Fungi are the principal decomposers in ecological systems; these and other differences place fungi in a single group of related organisms, named the Eumycota, which share a common ancestor, an interpretation, strongly supported by molecular phylogenetics. This fungal group oomycetes; the discipline of biology devoted to the study of fungi is known as mycology. In the past, mycology was regarded as a branch of botany, although it is now known fungi are genetically more related to animals than to plants.
Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, their cryptic lifestyles in soil or on dead matter. Fungi include symbionts of plants, animals, or other fungi and parasites, they may become noticeable when fruiting, either as molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange in the environment, they have long been used in the form of mushrooms and truffles. Since the 1940s, fungi have been used for the production of antibiotics, more various enzymes produced by fungi are used industrially and in detergents. Fungi are used as biological pesticides to control weeds, plant diseases and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans; the fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies.
Fungi can break down manufactured materials and buildings, become significant pathogens of humans and other animals. Losses of crops due to fungal diseases or food spoilage can have a large impact on human food supplies and local economies; the fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, morphologies ranging from unicellular aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of Kingdom Fungi, estimated at 2.2 million to 3.8 million species. Of these, only about 120,000 have been described, with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans. Since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christian Hendrik Persoon, Elias Magnus Fries, fungi have been classified according to their morphology or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits.
Phylogenetic studies published in the last decade have helped reshape the classification within Kingdom Fungi, divided into one subkingdom, seven phyla, ten subphyla. The English word fungus is directly adopted from the Latin fungus, used in the writings of Horace and Pliny; this in turn is derived from the Greek word sphongos, which refers to the macroscopic structures and morphology of mushrooms and molds. The word mycology is derived from the Greek logos, it denotes the scientific study of fungi. The Latin adjectival form of "mycology" appeared as early as 1796 in a book on the subject by Christiaan Hendrik Persoon; the word appeared in English as early as 1824 in a book by Robert Kaye Greville. In 1836 the English naturalist Miles Joseph Berkeley's publication The English Flora of Sir James Edward Smith, Vol. 5. Refers to mycology as the study of fungi. A group of all the fungi present in a particular area or geographic region is known as mycobiota, e.g. "the mycobiota of Ireland". Before the introduction of molecular methods for phylogenetic analysis, taxonomists considered fungi to be members of the plant kingdom because of similarities in lifestyle: both fungi and plants are immobile, have similarities in general morphology and growth habitat.
Like plants, fungi grow in soil and, in the case of mushrooms, form conspicuous fruit bodies, which sometimes resemble plants such as mosses. The fungi are now considered a separate kingdom, distinct from both plants and animals, from which they appear to have diverged around one billion years ago; some morphological and genetic features are shared with other organisms, while others are unique to the fungi separating them from the other kingdoms: Shared features: With other euka
The Calliphoridae are a family of insects in the order Diptera, with 1,200 known species. The maggot larvae used as fishing bait, are known as gentles; the family is known to be polyphyletic, but much remains disputed regarding proper treatment of the constituent taxa, some of which are accorded family status. The name blow fly comes from an older English term for meat that had eggs laid on it, said to be fly blown; the first known association of the term "blow" with flies appears in the plays of William Shakespeare: Love's Labour's Lost, The Tempest, Antony and Cleopatra. Calliphoridae adults are shiny with metallic colouring with blue, green, or black thoraces and abdomens. Antennae are aristate; the arista are plumose the entire length, the second antennal segment is distinctly grooved. Members of Calliphoridae have branched Rs 2 veins, frontal sutures are present, calypters are well developed; the characteristics and arrangement of hairlike bristles are used to tell the difference between members of this family.
All blow flies have bristles located on the meron. Having two notopleural bristles and a hindmost posthumeral bristle located lateral to presutural bristle are characteristics to look for when identifying this family; the thorax has the continuous dorsal suture across the middle, along with well-defined posterior calli. The postscutellum is weakly developed; the costa is unbroken and the subcosta is apparent on the insect. Most species of blow flies studied thus far are anautogenous; the current theory is that females visit carrion both for protein and egg laying, but this remains to be proven. Blow fly eggs yellowish or white in color, are about 1.5 mm x 0.4 mm, when laid, look like rice balls. While the female blow fly lays 150–200 eggs per batch, she is iteroparous, laying around 2,000 eggs during the course of her life; the sex ratio of blow fly eggs is 50:50, but one exception is females from two species of the genus Chrysomya, which are either arrhenogenic or thelygenic. Hatching from an egg to the first larval stage takes about eight hours to one day.
Larvae have three stages of development. The instars are separable by examining openings to the breathing system; the larvae use proteolytic enzymes in their excreta to break down proteins on the livestock or corpse on which they are feeding. Blow flies are poikilothermic – the rate at which they grow and develop is dependent on temperature and species. Under room temperature, the black blow fly Phormia regina can change from egg to pupa in 150–266 hours; when the third larval stage is complete, it will leave the corpse and burrow into the ground to pupate, emerging as an adult seven to fourteen days later. Adult blow flies are occasional pollinators, being attracted to flowers with strong odors resembling rotting meat, such as the American pawpaw or dead horse arum. Little doubt remains that these flies use nectar as a source of carbohydrates to fuel flight, but just how and when this happens is unknown. One study showed the visual stimulus a blow fly receives from its compound eyes is responsible for causing its legs to extend from its flight position and allow it to land on any surface.
Larvae of most species are scavengers of carrion and dung, most constitute the majority of the maggots found in such material, although they are not uncommonly found in close association with other dipterous larvae from the families Sarcophagidae and Muscidae, many other acalyptrate muscoid flies. Predators of blow flies include: spiders, beetles and birds including chickens. About 1,100 species of blow flies are known, with 228 species in the Neotropics, a large number of species in Africa and Southern Europe; the most common areas to find Calliphoridae species are in India, China, Central America, the Southern United States. The typical habitats for blow flies are temperate to tropical areas that provide a layer of loose, damp soil and litter where larvae may thrive and pupate; this is a selected list of genera from the Palearctic, Nearctic and Australasia: Sources: MYIA, FE, Nomina, A/O DC Blow flies have caught the interest of researchers in a variety of fields, although the large body of literature on calliphorids has been concentrated on solving the problem of myiasis in livestock.
The sheep blow fly Lucilia cuprina causes the Australian sheep industry an estimated AU$170 million a year in losses. The most common causes of myiasis in humans and animals are the three dipteran families Oestridae and Sarcophagidae. Myiasis in humans is clinically categorized in six ways: dermal and subdermal, facial cavity, wound or traumatic, gastrointestinal and generalized. If found in humans, the dipteran larvae are in their first instar; the only treatment necessary is just to remove the maggots, the patient heals naturally. Whilst not a myiasis species, the Congo floor maggot feeds on mammal blood human; the New World primary screwworm, once a major pest in southern United States, has been eradicated from the United States and Central America through an extensive release program by the USDA of sterilized males
Silphidae is a family of beetles that are known as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Nicrophorinae. Nicrophorines are sometimes known as sexton beetles; the number of species is small and around two hundred. They are more diverse in the temperate region. Both subfamilies feed on decaying organic matter such as dead animals; the subfamilies differ in which types of carcasses they prefer. Silphidae are considered to be of importance to forensic entomologists because when they are found on a decaying body they are used to help estimate a post-mortem interval; the family Silphidae belongs to the order Coleoptera. They are referred to as carrion beetles or burying beetles and are associated with carrion and dung. In the past, members of the family Agyrtidae were included; this family has two subfamilies and Nicrophorinae. The antenna is made up of 11 segments and is capitate in the Nicrophorinae and has a more gradual club shape in the Silphinae; the subfamilies differ in behavior.
Members of the subfamily Silphinae show little to no care for their young and breed on large carrion. Nicrophorinae breed on small animal carrion and will bury themselves and their food to rear their offspring in a bi-parental manner. There are 183 species in this family, which are found worldwide although they are commoner in the temperate region. Nicrophorus americanus, known as the American Burying Beetle, is an endangered species; the oldest beetle fossils are over 265 million years old dating back to the Permian period but the oldest fossil Silphid is that of N. humator dating around 10,500 years and described in 1962 by Pearson. Many Silphidae are flightless; this loss is thought to be a result due to the changes in habitat over time. Researchers have found that most flight-capable species in this group feed on vertebrate carcasses, whereas flightless species will feed on soil invertebrates, they found that egg production increased with flight loss because of a more limited food supply. The word "silphid" or "sylph", first seen in the sixteenth century in Paracelsus' works, refers to any race of spirits inhabiting the air and is described as mortal, but lacking soul.
The word is related to the Latin word sylva meaning "slender, graceful girl" and the Greek word nymph meaning "light, airy movements". Silphidae beetles are most abundant in the temperate zone; the diversity is greater in the temperate zone and they are quite rare in the tropics although there are species endemic in the region. It is thought that ants and other carrion feeders outcompete them in these regions, they vary in size from 7 to 45 mm. There are about 46 different species of Silphidae in North America which include Heterosilpha ramosa, Necrodes surinamensis, Necrophila americana, Nicrophorus americanus, Nicrophorus carolinus, Nicrophorus investigator, Nicrophorus marginatus, Nicrophorus orbicollis, Nicrophorus tomentosus, Oiceoptoma inaequale, Oiceoptoma noveboracense, Oiceoptoma rugulosum, Thanatophilus lapponicus. A species found in the United Kingdom is Oiceoptoma thoracicum; the Nicrophorinae have a narrower distribution than the Silphinae. Tropical forms include Diamesus of Asia and Australia, Ptomophila in Australia and Nicrophorus mexico of Central America.
Silphidae undergo holometabolous development. The development in the subfamily Silphinae proceeds at a slower rate than in Nicrophorinae; the Silphinae life cycle takes twenty six to fifty eight days to go from an egg to adult. The breakdown of this process is essential to forensic entomologists; the cycle takes. The larvae will develop through three instars on the carrion lasting for ten to thirty days. After that time period is up the third instar larvae will venture away from the detritus to pupate. Pupation takes fourteen to twenty one days and is the major part of metamorphosis where a grandiose change occurs. During this stage the wings become developed and sexual maturity is reached, sometimes called the imago or adult stage where the cycle is repeated; the Nicrophorinae cycle is quicker. Oviposition is done near the carcass and takes twelve to forty eight hours for the eggs to hatch into larvae; the amount of food and parental care exhibited help determine the length of the larval stage. Pupation in this subfamily is completed in the soil.
The adult Nicrophorinae will emerge from the venture to find food and a mate. Nicrophorinae are well known for the habit of locating a carcass and burying it by unearthing the soil underneath it; the burying behavior has evolved to prevent competition from other insects such as fly maggots. It has been observed. More than not a breeding pair will work together, but in cases where there is large carrion males try to boost their reproduction by emitting pheromones. In this way, he will father more offspring, but the reproductive success of the primary female declines. Sometimes, where there is a large carcass the likelihood of intense competition from flies leads to communal breeding. There appears to be a truce between females who would compete for the males, in these cases cooperative behavior extends to females caring for each other's offspring. At the height of breeding season pairs of beetles may compete for the carrion; the losing pair will be ejected from the carrion and if any eggs have been laid they are killed so the new female can lay her own.
The Silphidae adults feed in a saprophagous mann
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. A few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, are present in most of its habitats. Bacteria inhabit soil, acidic hot springs, radioactive waste, the deep portions of Earth's crust. Bacteria live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, only about half of the bacterial phyla have species that can be grown in the laboratory; the study of bacteria is known as a branch of microbiology. There are 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants and animals. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere.
The nutrient cycle includes the decomposition of dead bodies. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Data reported by researchers in October 2012 and published in March 2013 suggested that bacteria thrive in the Mariana Trench, with a depth of up to 11 kilometres, is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, "You can find microbes everywhere—they're adaptable to conditions, survive wherever they are."The famous notion that bacterial cells in the human body outnumber human cells by a factor of 10:1 has been debunked. There are 39 trillion bacterial cells in the human microbiota as personified by a "reference" 70 kg male 170 cm tall, whereas there are 30 trillion human cells in the body.
This means that although they do have the upper hand in actual numbers, it is only by 30%, not 900%. The largest number exist in the gut flora, a large number on the skin; the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial in the gut flora. However several species of bacteria are pathogenic and cause infectious diseases, including cholera, anthrax and bubonic plague; the most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and are used in farming, making antibiotic resistance a growing problem. In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, the recovery of gold, palladium and other metals in the mining sector, as well as in biotechnology, the manufacture of antibiotics and other chemicals.
Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two different groups of organisms that evolved from an ancient common ancestor; these evolutionary domains are called Archaea. The word bacteria is the plural of the New Latin bacterium, the latinisation of the Greek βακτήριον, the diminutive of βακτηρία, meaning "staff, cane", because the first ones to be discovered were rod-shaped; the ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, bacteria and archaea were the dominant forms of life. Although bacterial fossils exist, such as stromatolites, their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species.
However, gene sequences can be used to reconstruct the bacterial phylogeny, these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. The most recent common ancestor of bacteria and archaea was a hyperthermophile that lived about 2.5 billion–3.2 billion years ago. Bacteria were involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves related to the Archaea; this involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya. Some eukaryotes that contained mitochondria engulfed cyanobacteria-like organisms, leading to the formation of chloroplasts in algae and plants; this is known as primary endosymbiosis. Bacteria display a wide diversity of sizes, called morphologies.
Bacterial cells are about one-tenth the size of eukaryotic cells
Hawks are a group of medium-sized diurnal birds of prey of the family Accipitridae. Hawks are distributed and vary in size; the subfamily Accipitrinae includes goshawks, sharp-shinned hawks and others. This subfamily are woodland birds with long tails and high visual acuity, they hunt by dashing from a concealed perch. In the Americas, members of the Buteo group are called hawks. Buteos have broad wings and sturdy builds, they are larger-winged, shorter-tailed and fly further distances in open areas than accipiters. Buteos pounce on their prey rather than hunting in a fast horizontal pursuit; the terms accipitrine hawk and buteonine hawk are used to distinguish between the types in regions where hawk applies to both. The term "true hawk" is sometimes used for the accipitrine hawks in regions where buzzard is preferred for the buteonine hawks. All these groups are members of the Accipitridae family, which includes the hawks and buzzards as well as kites and eagles; some authors use "hawk" for any small to medium Accipitrid, not an eagle.
The common names of some birds include the term "hawk", reflecting traditional usage rather than taxonomy. For example, some people may call an osprey a "fish hawk" or a peregrine falcon a "duck hawk". Falconry was once called "hawking" and any bird used for falconry could be referred to as a hawk. Aristotle listed eleven types of ἱέρακες: aisalōn, hypotriorchēs, leios, phassophonos, pternis and triorchēs. Pliny numbered sixteen kinds of hawks, but named only aigithos, kenchrēïs, triorchēs; the accipitrine hawks hunt birds as their primary prey. They are called "hen-hawks", or "wood-hawks" because of their woodland habitat; the subfamily Accipitrinae contains Accipiter. Melierax may be given a subfamily of its own. Erythrotriorchis is traditionally included in Accipitrinae, but is a convergent genus from an unrelated group; the "Buteo group" includes genera Buteo, Parabuteo and most of Leucopternis. Members of this group have been called "hawk-buzzards". Proposed new genera Morphnarchus and Pseudastur are formed from members of Buteo and Leucopternis.
The "Buteogallus group" are called hawks, with the exception of the solitary eagles. Buteo is the type genus of the subfamily Buteoninae. Traditionally this subfamily includes eagles and sea-eagles. Lerner and Mindell proposed placing those into separate subfamilies, leaving only the buteonine hawks/buzzards in Buteoninae. In February 2005, Canadian ornithologist Louis Lefebvre announced a method of measuring avian "IQ" by measuring their innovation in feeding habits. Based on this scale, hawks were named among the most intelligent birds. Hawks have four types of colour receptors in the eye; these give hawks the ability to perceive not only the visible range but the ultraviolet part of the spectrum. Other adaptations allow for the detection of polarised magnetic fields; this is due to the large number of photoreceptors in the retina, a high number of nerves connecting these receptors to the brain, an indented fovea, which magnifies the central portion of the visual field. Hawks are known to be able hunters.
The female is larger than the male. Like most birds, the hawk migrates in the spring. Different types of hawks choose separate times in each season to migrate; the autumn migrating season ends mid-December. It has been studied; the long-distance travelers tend to begin in early autumn while the short distance travelers start much later. Thus, the longer the distance the earlier the bird begins its journey. There have been studies on the speed and efficiency of the bird's migration that show that it is better for a hawk to arrive at its destination as early as possible; this is because the first bird that arrives has the first pick of mates, living area and survival necessities. The more fat a bird has when it starts its migration, the better chance it has of making the trip safely. Kerlinger states that studies have shown that a bird has more body fat when it begins its migration, before it leaves, than when has arrived at its destination. One of the most important parts of the hawk's migration is the flight direction because the direction or path the bird chooses to take could affect its migration.
The force of wind is a variable because it could either throw the bird off course or push it in the right direction, depending on the direction of the wind. To ensure a safer journey, a hawk tries to avoid any large bodies of water in the spring and fall by detouring around a lake or flying along a border. Hawkwatching is a citizen scientist activity that monitors hawk migration and provides data to the scientific community; the red-tailed hawk is the most common hawk in North America. Past observations have indicated that while hawks can adapt to any surrounding, hawks prefer a habitat, open. Hawks like to live in places like deserts and fields as it is easier to find prey; as they are able to live anywhere, they can be found in mountainous plains and tropical, moist areas. Hawks have been found in places such as Centra