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Siphonaptera Genera
Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, are usually dark in color, and have bodies that are "flattened" sideways or narrow, enabling them to move through their hosts' fur or feathers. They lack wings; their hind legs are extremely well adapted for jumping. Their claws keep them from being dislodged, and their mouthparts are adapted for piercing skin and sucking blood. Some species can leap 50 times their body length, a feat second only to jumps made by another group of insects, the superfamily of froghoppers. Flea larvae are worm-like, with no limbs; they have chewing mouthparts and feed on organic debris left on their hosts' skin. Genetic evidence indicates that fleas are a specialised lineage of parasitic scorpionflies (Mecoptera) ''sensu lato'', most closely related to the fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scanning Electron Microscope
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector ( Everhart–Thornley detector). The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer. Specimens are observed in high vacuum in a conventional SEM, or in low vacuum or wet conditions in a variable pressure or environmental SEM, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cenozoic
The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three geological eras of the Phanerozoic Eon, preceded by the Mesozoic and Paleozoic. The Cenozoic started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor. The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammalsthe eutherians ( placentals) in the Northern Hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the Southern Hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Donne
John Donne ( ; 1571 or 1572 – 31 March 1631) was an English poet, scholar, soldier and secretary born into a recusant family, who later became a clergy, cleric in the Church of England. Under Royal Patronage, he was made Dean of St Paul's, Dean of St Paul's Cathedral in London (1621–1631). He is considered the preeminent representative of the metaphysical poets. His poetical works are noted for their metaphorical and sensual style and include sonnets, love poems, religious poems, Latin translations, epigrams, elegies, songs and satires. He is also known for his sermons. Donne's style is characterised by abrupt openings and various paradoxes, ironies and dislocations. These features, along with his frequent dramatic or everyday speech rhythms, his tense syntax and his tough eloquence, were both a reaction against the smoothness of conventional Elizabethan poetry and an adaptation into English of European baroque and mannerist techniques. His early career was marked by poetry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flea Circus
A flea circus is a circus sideshow attraction in which fleas are attached (or appear to be attached) to miniature carts and other items, and encouraged to perform circus acts within a small housing. History The first records of flea performances were from watchmakers who were demonstrating their metalworking skills. In 1578, the London blacksmith Mark Scaliot produced a lock and chain that were attached to a flea. The first recorded flea circus dates back to the early 1820s, when an Italian impresario named Louis Bertolotto advertised an "extraordinary exhibition of industrious fleas" on Regent Street, London. Bertolotto's flea shows included "four card-playing fleas, a flea orchestra (allegedly playing audibly), and a reenactment of Napoleon's defeat at Waterloo". Bertolotto's book ''The History of the Flea'' (c. 1833) also promoted flea circuses. Flea performances with military themes such as staged "sword fights" among fleas, were popular in the 19th century. Some flea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Death
The Black Death was a bubonic plague pandemic that occurred in Europe from 1346 to 1353. It was one of the list of epidemics, most fatal pandemics in human history; as many as people perished, perhaps 50% of Europe's 14th century population. The disease is caused by the Bacteria, bacterium ''Yersinia pestis'' and spread by Flea, fleas and through the air. One of the most significant events in European history, the Black Death had far-reaching population, economic, and cultural impacts. It was the beginning of the second plague pandemic. The plague created religious, social and economic upheavals, with profound effects on the course of European history. The origin of the Black Death is disputed. Genetic analysis suggests ''Yersinia pestis'' bacteria evolved approximately 7,000 years ago, at the beginning of the Neolithic, with flea-mediated strains emerging around 3,800 years ago during the late Bronze Age. The immediate territorial origins of the Black Death and its outbreak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plague Of Justinian
The plague of Justinian or Justinianic plague (AD 541–549) was an epidemic of Plague (disease), plague that afflicted the entire Mediterranean basin, Mediterranean Basin, Europe, and the Near East, especially the Sasanian Empire and the Byzantine Empire. The plague is named for the Byzantine Emperor Justinian I (r. 527–565) who, according to his Court (royal), court historian Procopius, contracted the disease and recovered in 542, at the height of the epidemic which killed about a fifth of the population in the imperial capital Constantinople, Constantinople. The contagion arrived in Roman Egypt in 541, spread around the Mediterranean Sea until 544, and persisted in Northern Europe and the Arabian Peninsula until 549. By 543, the plague had spread to every corner of the empire. The plague's severity and impact remain debated. Some scholars assert that as the first episode of the first plague pandemic, it had profound economic, social, and political effects across Europe an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Rat
The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is now found worldwide. The black rat is black to light brown in colour with a lighter underside. It is a generalist omnivore and a serious Pest (organism), pest to farmers because it feeds on a wide range of agricultural crops. It is sometimes kept as a pet. In parts of India, it is considered sacred and respected in the Karni Mata Temple in Deshnoke. Taxonomy ''Mus rattus'' was the scientific name proposed by Carl Linnaeus in 1758 for the black rat. Three subspecies were once recognized, but today are considered invalid and are now known to be actually Morph (zoology), color morphs: *''Rattus rattus rattus'' – roof rat *''Rattus rattus alexandrinus'' – Alexandrine rat *''Rattus rattus frugivorus'' – fruit rat Characteristics A ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bubonic Plague
Bubonic plague is one of three types of Plague (disease), plague caused by the Bacteria, bacterium ''Yersinia pestis''. One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting, as well as Lymphadenopathy, swollen and painful lymph nodes occurring in the area closest to where the bacteria entered the skin. Acral necrosis, the dark discoloration of skin, is another symptom. Occasionally, swollen lymph nodes, known as "buboes", may break open. The three types of plague are the result of the route of infection: bubonic plague, septicemic plague, and pneumonic plague. Bubonic plague is mainly spread by infected fleas from small animals. It may also result from exposure to the body fluids from a dead plague-infected animal. Mammals such as rabbits, hares, and some cat species are susceptible to bubonic plague, and typically die upon contraction. In the bubonic form of plague, the bacteria enter through the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterium
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit the air, soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. 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. Bacteria also live in mutualistic, commensal and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yersinia Pestis
''Yersinia pestis'' (''Y. pestis''; formerly ''Pasteurella pestis'') is a Gram-negative bacteria, gram-negative, non-motile bacteria, non-motile, coccobacillus Bacteria, bacterium without Endospore, spores. It is related to pathogens ''Yersinia enterocolitica'', and ''Yersinia pseudotuberculosis'', from which it evolved. ''Yersinia pestis'' is responsible for the disease plague (disease), plague, which caused the Plague of Justinian and the Black Death, one of the deadliest pandemics in recorded history. Plague takes three main forms: Pneumonic plague, pneumonic, Septicemic plague, septicemic, and bubonic plague, bubonic. ''Y. pestis'' is a facultative anaerobic organism, facultative anaerobic Parasitism, parasitic bacterium that can infect humans primarily via its host the Oriental rat flea (''Xenopsylla cheopis''), but also through airborne transmission , aerosols and airborne droplets for its pneumonic form. As a parasite of its host, the rat flea, which is also a parasit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector (epidemiology)
In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking (Hematophagy, hematophagous) arthropods such as mosquitoes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected the stomach tissue of a mosquito. Arthropods Arthropods form a major group of pathogen vectors with mosquitoes, Fly, flies, Sandfly, sand flies, lice, fleas, ticks, and mites transmitting a huge number of pathogens. Many such vectors are haematophagous, which feed on blood at some or all stages of their lives. When the insects and ticks feed on blood, the pathogen enters the blood stream of the host. This can happen in different ways. The ''Anopheles'' mosquito, a vector for malaria, filariasis, and various arthropod-borne-viruses (arboviruses), inserts its delicate mouthpart under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenopsylla Cheopis
The Oriental rat flea (''Xenopsylla cheopis''), also known as the tropical rat flea or the rat flea, is a parasite of rodents, primarily of the genus ''Rattus'', and is a primary Vector (epidemiology), vector for bubonic plague, plague and murine typhus. This occurs when a flea that has fed on an infected rodent bites a human, although this flea can live on any warm blooded mammal. Body structure The Oriental rat flea has no genal or pronotal combs. This characteristic can be used to differentiate the Oriental rat flea from the cat flea, dog flea, and other fleas. The flea's body is about one tenth of an inch long (about ). Its body is constructed to make it easier to jump long distances. The flea's body consists of three regions: head, thorax, and abdomen. The head and the thorax have rows of bristles (called combs), and the abdomen consists of eight visible segments. A flea's mouth has two functions: one for squirting saliva or partly digested blood into the bite, and one for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
