The silkworm is the larva or caterpillar of the domestic silkmoth, Bombyx mori. It is an economically important insect. A silkworm's preferred food is white mulberry leaves, though they may eat other mulberry species and osage orange. Domestic silkmoths are dependent on humans for reproduction, as a result of millennia of selective breeding. Wild silkmoths are different from their domestic cousins. Sericulture, the practice of breeding silkworms for the production of raw silk, has been under way for at least 5,000 years in China, whence it spread to India, Korea and the West; the silkworm was domesticated from the wild silkmoth Bombyx mandarina, which has a range from northern India to northern China, Korea and the far eastern regions of Russia. The domesticated silkworm derives from Chinese rather than Korean stock. Silkworms were unlikely to have been domestically bred before the Neolithic age. Before the tools to manufacture quantities of silk thread had not been developed; the domesticated B. mori and the wild B. mandarina can still sometimes produce hybrids.
Domestic silkmoths are different from most members in the genus Bombyx. Mulberry silkworms can be categorized into types; the major groups of silkworms fall under the bivoltine categories. The univoltine breed is linked with the geographical area within greater Europe; the eggs of this type hibernate during winter due to the cold climate, cross-fertilize only by spring, generating silk only once annually. The second type is called bivoltine and is found in China and Korea; the breeding process of this type takes place twice annually, a feat made possible through the warmer climates and the resulting two life cycles. The polyvoltine type of mulberry silkworm can only be found in the tropics; the eggs are laid by female moths and hatch within nine to 12 days, so the resulting type can have up to eight separate life cycles throughout the year. Eggs take about 14 days to hatch into larvae, they have a preference for white mulberry. They are not monophagous since they can eat other species of Morus, as well as some other Moraceae Osage orange.
They are covered with tiny black hairs. When the color of their heads turns darker, it indicates. After molting, the larval phase of the silkworms emerge white and with little horns on their backs. After they have molted four times, their bodies become yellow and the skin becomes tighter; the larvae prepare to enter the pupal phase of their lifecycle, enclose themselves in a cocoon made up of raw silk produced by the salivary glands. The final molt from larva to pupa takes place within the cocoon, which provides a vital layer of protection during the vulnerable motionless pupal state. Many other Lepidoptera produce cocoons, but only a few—the Bombycidae, in particular the genus Bombyx, the Saturniidae, in particular the genus Antheraea—have been exploited for fabric production. If the animal is allowed to survive after spinning its cocoon and through the pupal phase of its lifecycle, it releases proteolytic enzymes to make a hole in the cocoon so it can emerge as an adult moth; these enzymes are destructive to the silk and can cause the silk fibers to break down from over a mile in length to segments of random length, which reduces the value of the silk threads, but not silk cocoons used as "stuffing" available in China and elsewhere for doonas, jackets etc.
To prevent this, silkworm cocoons are boiled. The heat kills the water makes the cocoons easier to unravel; the silkworm itself is eaten. As the process of harvesting the silk from the cocoon kills the larva, sericulture has been criticized by animal welfare and rights activists. Mahatma Gandhi was critical of silk production based on the Ahimsa philosophy "not to hurt any living thing"; this led to Gandhi's promotion of cotton spinning machines, an example of which can be seen at the Gandhi Institute. He promoted Ahimsa silk, wild silk made from the cocoons of wild and semiwild silkmoths; the moth – the adult phase of the lifecycle – is not capable of functional flight, in contrast to the wild B. mandarina and other Bombyx species, whose males fly to meet females and for evasion from predators. Some may emerge with the ability to lift off and stay airborne, but sustained flight cannot be achieved; this is because their bodies are too heavy for their small wings. However, some silkmoths can still fly.
Silkmoths have a wingspan of 3 -- a white, hairy body. Females are about two to three times bulkier than males, but are colored. Adult Bombycidae do not feed, though a human caretaker can feed them; the cocoon is made of a thread of raw silk from 300 to about 900 m long. The fibers are fine and lustrous, about 10 μm in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk. At least 70 million pounds of raw silk are produced each year. Due to its small size and ease of culture, the silkworm has become a model organism in the study of lepidopteran and arthropod biology. Fundamental findings on pheromones, brain structures, physiology have been made with the silkworm. One example of this was the m
Louse is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include every species of bird and mammal, except for monotremes and bats. Lice are vectors of diseases such as typhus. Chewing lice live among the hairs or feathers of their host and feed on skin and debris, while sucking lice pierce the host's skin and feed on blood and other secretions, they spend their whole life on a single host, cementing their eggs, called nits, to hairs or feathers. The eggs hatch into nymphs, which moult three times before becoming grown, a process that takes about four weeks. Humans host two species of louse—the head louse and the body louse are subspecies of Pediculus humanus; the body louse has the smallest genome of any known insect. Lice were ubiquitous in human society until at least the Middle Ages, they appear in folktales, songs such as The Kilkenny Louse House, novels such as James Joyce's Finnegans Wake.
They feature in the psychiatric disorder delusional parasitosis. A louse was one of the early subjects of microscopy, appearing in Robert Hooke's 1667 book, Micrographia. Humans host three different kinds of lice: head lice, body lice, pubic lice. Lice infestations can be controlled with lice combs, medicated shampoos or washes. Sucking lice are small wingless insects ranging from 0.5 to 5 mm in length. They have oval, flattened bodies, they have no ocelli, their compound eyes are reduced in size or absent. Their antennae are short with three to five segments, their mouth parts, which are retractable into their head, are adapted for piercing and sucking. There is a cibarial pump at the start of the gut; the mouthparts consist of a proboscis, toothed, a set of stylets arranged in a cylinder inside the proboscis, containing a salivary canal and a food canal. The thoracic segments are fused, the abdominal segments are separate, there is a single large claw at the tip of each of the six legs. Chewing lice are flattened and can be larger than sucking lice, ranging in length from 0.5 to 6 mm.
They are similar to sucking lice in form but the head is wider than the thorax and all species have compound eyes. There are no ocelli and the mouthparts are adapted for chewing; the antennae have three to five segments and are slender in the suborder Ischnocera, but club-shaped in the suborder Amblycera. The legs are short and robust, terminated by one or two claws. Many lice have co-evolved with it, they are cryptically coloured to match the fur or feathers of the host. Lice are divided into two groups: sucking lice, which obtain their nourishment from feeding on the sebaceous secretions and body fluids of their host. Most are found on only specific types of animals, and, in some cases, on only a particular part of the body. For example, in humans, different species of louse inhabit pubic hair. Lice cannot survive for long if removed from their host; some species of chewing lice house symbiotic bacteria in bacteriocytes in their bodies. These may assist in digestion. If their host dies, lice can opportunistically use phoresis to hitch a ride on a fly and attempt to find a new host.
A louse's color varies from pale beige to dark gray. Female lice are more common than males, some species are parthenogenetic, with young developing from unfertilized eggs. A louse's egg is called a nit. Many lice attach their eggs to their hosts' hair with specialized saliva. Lice inhabiting birds, may leave their eggs in parts of the body inaccessible to preening, such as the interior of feather shafts. Living louse eggs tend to be pale whitish. Lice are exopterygotes; the young moult three times before reaching the final adult form within a month after hatching. The average number of lice per host tends to be higher in large-bodied bird species than in small ones. Lice have an aggregated distribution across bird individuals, i.e. most lice live on a few birds, while most birds are free of lice. This pattern is more pronounced in territorial than in colonial—more social—bird species. Host organisms that dive under water to feed on aquatic prey harbor fewer taxa of lice. Bird taxa that are capable of exerting stronger antiparasitic defense—such as stronger T cell immune response or larger uropygial glands—harbor more taxa of Amblyceran lice than others.
Reductions in the size of host populations may cause a long-lasting reduction of louse taxonomic richness, for example, birds introduced into New Zealand host fewer species of lice there than in Europe. Louse sex ratios are more balanced in more social hosts and more female-biased in less social hosts due to the stronger isolation among louse subpopulations in the latter case; the extinction of a species results in the extinction of its host-specific lice. Host-switching i
Plants are multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. Plants were treated as one of two kingdoms including all living things that were not animals, all algae and fungi were treated as plants. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes. By one definition, plants form the clade Viridiplantae, a group that includes the flowering plants and other gymnosperms and their allies, liverworts and the green algae, but excludes the red and brown algae. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria, their chloroplasts contain b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is common.
There are about 320 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants. Green plants provide a substantial proportion of the world's molecular oxygen and are the basis of most of Earth's ecosystems on land. Plants that produce grain and vegetables form humankind's basic foods, have been domesticated for millennia. Plants have many cultural and other uses, as ornaments, building materials, writing material and, in great variety, they have been the source of medicines and psychoactive drugs; the scientific study of plants is known as a branch of biology. All living things were traditionally placed into one of two groups and animals; this classification may date from Aristotle, who made the distincton between plants, which do not move, animals, which are mobile to catch their food. Much when Linnaeus created the basis of the modern system of scientific classification, these two groups became the kingdoms Vegetabilia and Animalia. Since it has become clear that the plant kingdom as defined included several unrelated groups, the fungi and several groups of algae were removed to new kingdoms.
However, these organisms are still considered plants in popular contexts. The term "plant" implies the possession of the following traits multicellularity, possession of cell walls containing cellulose and the ability to carry out photosynthesis with primary chloroplasts; when the name Plantae or plant is applied to a specific group of organisms or taxon, it refers to one of four concepts. From least to most inclusive, these four groupings are: Another way of looking at the relationships between the different groups that have been called "plants" is through a cladogram, which shows their evolutionary relationships; these are not yet settled, but one accepted relationship between the three groups described above is shown below. Those which have been called "plants" are in bold; the way in which the groups of green algae are combined and named varies between authors. Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom.
The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the green algae, red algae and brown algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, they are no longer classified as plants as defined here; the Viridiplantae, the green plants – green algae and land plants – form a clade, a group consisting of all the descendants of a common ancestor. With a few exceptions, the green plants have the following features in common, they undergo closed mitosis without centrioles, have mitochondria with flat cristae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. Two additional groups, the Rhodophyta and Glaucophyta have primary chloroplasts that appear to be derived directly from endosymbiotic cyanobacteria, although they differ from Viridiplantae in the pigments which are used in photosynthesis and so are different in colour.
These groups differ from green plants in that the storage polysaccharide is floridean starch and is stored in the cytoplasm rather than in the plastids. They appear to have had a common origin with Viridiplantae and the three groups form the clade Archaeplastida, whose name implies that their chloroplasts were derived from a single ancient endosymbiotic event; this is the broadest modern definition of the term'plant'. In contrast, most other algae not only have different pigments but have chloroplasts with three or four surrounding membranes, they are not close relatives of the Archaeplastida having acquired chloroplasts separately from ingested or symbiotic green and red algae. They are thus not included in the broadest modern definition of the plant kingdom, although they were in the past; the green plants or Viridiplantae were traditionally divided into the green algae (including
A feral animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some cases, contributed to extinction of indigenous species; the removal of feral species is a major focus of island restoration. A feral animal is one that has escaped from a domestic or captive status and is living more or less as a wild animal, or one, descended from such animals. Other definitions include animals that have changed from being domesticated to being wild, natural, or untamed; some common examples of animals with feral populations are horses, goats and pigs. Zoologists exclude from the feral category animals that were genuinely wild before they escaped from captivity: neither lions escaped from a zoo nor the sea eagles re-introduced into the UK are regarded as feral. Domesticated plants that revert to wild are referred to as escaped, naturalized, or sometimes as feral crops.
Individual plants are known as volunteers. Large numbers of escaped plants may become a noxious weed; the adaptive and ecological variables seen in plants that go wild resemble those of animals. Feral populations of crop plants, along with hybridization between crop plants and their wild relatives, brings a risk that genetically engineered characteristics such as pesticide resistance could be transferred to weed plants; the unintended presence of genetically modified crop plants or of the modified traits in other plants as a result of cross-breeding is known as "adventitious presence". Certain familiar animals go feral and while others are much less inclined to wander and fail promptly outside domestication; some species will detach from humans and pursue their own devices, but do not stray far or spread readily. Others depart and are gone, seeking out new territory or range to exploit and displaying active invasiveness. Whether they leave and venture far, the ultimate criterion for success is longevity.
Persistence depends on their ability to establish themselves and reproduce reliably in the new environment. Neither the duration nor the intensity with which a species has been domesticated offers a useful correlation with its feral potential; the cat returns to a feral state if it has not been socialized when young. These cats if left to proliferate, are considered to be pests in both rural and urban areas, may be blamed for devastating the bird and mammal populations. A local population of feral cats living in an urban area and using a common food source is sometimes called a feral cat colony; as feral cats multiply it is difficult to control their populations. Animal shelters attempt to adopt out feral cats kittens, but are overwhelmed with sheer numbers and euthanasia is used. In rural areas, excessive numbers of feral cats are shot. More the "trap-neuter-return" method has been used in many locations as an alternative means of managing the feral cat population; the goat is one of the oldest domesticated creatures, yet goes feral and does quite well on its own.
Sheep are close contemporaries and cohorts of goats in the history of domestication, but the domestic sheep is quite vulnerable to predation and injury, thus seen in a feral state. However, in places where there are few predators, they get on well, for example in the case of the Soay sheep. Both goats and sheep were sometimes intentionally released and allowed to go feral on island waypoints frequented by mariners, to serve as a ready food source; the dromedary camel, domesticated for well over 3,000 years, will readily go feral. A substantial population of feral dromedaries, descended from pack animals that escaped in the 19th and early 20th centuries, thrives in the Australian interior today. Water buffalo run rampant in Northern Australia; the Australian government encourages the hunting of feral water buffalo because of their large numbers. Cattle have been domesticated since the neolithic era, but can do well enough on open range for months or years with little or no supervision, their ancestors, the aurochs, were quite fierce, on par with the modern Cape buffalo.
Modern cattle those raised on open range, are more docile, but when threatened can display aggression. Cattle those raised for beef, are allowed to roam quite and have established long term independence in Australia, New Zealand and several Pacific Islands along with small populations of semi-feral animals roaming the southwestern United States and northern Mexico; such cattle are variously called scrubbers or cleanskins. Most free roaming cattle, however untamed, are too valuable not to be rounded up and recovered in settled regions. Horses and donkeys, domesticated about 5000 BC, are feral in open grasslands worldwide. In Portugal, feral horses are called Sorraia. Other isolated feral populations exist, including the Banker horse, they are referred to as "wild horses", but this is a misnomer. There are "wild" horses that have never been domesticated, most notably Przewalski's horse. While the horse was indigenous to North America, the wild ancestor died out at the end of the last Ice Age. In both Australia and the Americas, modern "wild" horses descended from domesticated horses brought by European explorers and settlers that escaped and thrived.
Australia hosts a feral donkey population, as do the Virgin Islands and the Americ
A pet or companion animal is an animal kept for a person's company, entertainment, or as an act of compassion such as taking in and protecting a hungry stray cat, rather than as a working animal, livestock, or laboratory animal. Popular pets are noted for their attractive appearances and relatable personalities, or may just be accepted as they are because they need a home. Two of the most popular pets are cats; the technical term for a cat lover is an ailurophile, for a dog lover, a cynophile. Other animals kept include rabbits. Small pets may be grouped together as pocket pets, while the equine and bovine group include the largest companion animals. Pets provide their owners both emotional benefits. Walking a dog can provide both the human and the dog with exercise, fresh air, social interaction. Pets can give companionship to people who are living alone or elderly adults who do not have adequate social interaction with other people. There is a medically approved class of therapy animals dogs or cats, that are brought to visit confined humans, such as children in hospitals or elders in nursing homes.
Pet therapy utilizes trained animals and handlers to achieve specific physical, cognitive or emotional goals with patients. Some scholars and animal rights organizations have raised concerns over keeping pets because of the lack of autonomy and objectification of nonhuman animals. There are 86.4 million pet cats and 78.2 million pet dogs in the United States, a United States 2007–2008 survey showed that dog-owning households outnumbered those owning cats, but that the total number of pet cats was higher than that of dogs. The same was true for 2011. In 2013, pets outnumbered children four to one in the United States. For a small to medium-size dog, the total cost over a dog's lifetime is about $7,240 to $12,700. For an indoor cat, the total cost over a cat's lifetime is about $8,620 to $11,275. People most get pets for companionship, to protect a home or property, or because of the beauty or attractiveness of the animals; the most common reasons for not owning a pet are lack of time, lack of suitable housing, lack of ability to care for the pet when traveling.
According to the 2007-2008 Pet Owners survey: The latest survey done by Colin Siren of Ipsos Reid estimates that there are 7.9 million cats and 5.9 million dogs in Canada. The survey shows that 35% of Canadian households have a dog, while 38% have a cat, consistent with other surveys conducted around the world. In China, spending on domestic animals has grown from and estimated $3.12 billion in 2010 to $25 billion in 2018. The Chinese people own 51 million dogs and 41 million cats, with pet owners preferring to source pet food internationally. A 2007 survey by the University of Bristol found that 26% of UK households owned cats and 31% owned dogs, estimating total domestic populations of 10.3 million cats and 10.5 million dogs in 2006. The survey found that 47.2% of households with a cat had at least one person educated to degree level, compared with 38.4% of homes with dogs. According to a survey promoted by Italian family associations in 2009, it is estimated that there are 45 million pets in Italy.
This includes 7 million dogs, 7.5 million cats, 16 million fish, 12 million birds, 10 million snakes. Keeping animals as pets may be detrimental to their health if certain requirements are not met. An important issue is inappropriate feeding; the consumption of chocolate or grapes by dogs, for example, may prove fatal. Certain species of houseplants can prove toxic if consumed by pets. Examples include philodendrons and Easter lilies and poinsettias and aloe vera. Housepets dogs and cats in industrialized societies, are highly susceptible to obesity. Overweight pets have been shown to be at a higher risk of developing diabetes, liver problems, joint pain, kidney failure, cancer. Lack of exercise and high-caloric diets are considered to be the primary contributors to pet obesity, it is believed among the public, among many scientists, that pets bring mental and physical health benefits to their owners. A recent dissent comes from a 2017 RAND study, which found that at least in the case of children, having a pet per se failed to improve physical or mental health by a statistically significant amount.
Conducting long-term randomized trials to settle the issue would be costly or infeasible. Pets might have the ability to stimulate their caregivers, in particular the elderly, giving people someone to take care of, someone to exercise with, someone to help them heal from a physically or psychologically troubled past. Animal company can help people to preserve acceptable levels of happiness despite the presence of mood symptoms like anxiety or depression. Having a pet may help people achieve health goals, such as lowered blood pressure, or mental goals, such as decreased stress. Ther
Cattle—colloquially cows—are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, are most classified collectively as Bos taurus. Cattle are raised as livestock for meat, for milk, for hides, which are used to make leather, they are used as riding animals and draft animals. Another product of cattle is dung, which can be used to create fuel. In some regions, such as parts of India, cattle have significant religious meaning. Cattle small breeds such as the Miniature Zebu, are kept as pets. Around 10,500 years ago, cattle were domesticated from as few as 80 progenitors in central Anatolia, the Levant and Western Iran. According to an estimate from 2011, there are 1.4 billion cattle in the world. In 2009, cattle became one of the first livestock animals to have a mapped genome; some consider cattle the oldest form of wealth, cattle raiding one of the earliest forms of theft. Cattle were identified as three separate species: Bos taurus, the European or "taurine" cattle.
The aurochs is ancestral to both taurine cattle. These have been reclassified as one species, Bos taurus, with three subspecies: Bos taurus primigenius, Bos taurus indicus, Bos taurus taurus. Complicating the matter is the ability of cattle to interbreed with other related species. Hybrid individuals and breeds exist, not only between taurine cattle and zebu, but between one or both of these and some other members of the genus Bos – yaks and gaur. Hybrids such as the beefalo breed can occur between taurine cattle and either species of bison, leading some authors to consider them part of the genus Bos, as well; the hybrid origin of some types may not be obvious – for example, genetic testing of the Dwarf Lulu breed, the only taurine-type cattle in Nepal, found them to be a mix of taurine cattle and yak. However, cattle cannot be hybridized with more distantly related bovines such as water buffalo or African buffalo; the aurochs ranged throughout Europe, North Africa, much of Asia. In historical times, its range became restricted to Europe, the last known individual died in Mazovia, Poland, in about 1627.
Breeders have attempted to recreate cattle of similar appearance to aurochs by crossing traditional types of domesticated cattle, creating the Heck cattle breed. The noun cattle encompasses both sexes; the singular, technically means the female, the male being bull. The plural form cows is sometimes used colloquially to refer to both sexes collectively, as e.g. in a herd, but that usage can be misleading as the speaker's intent may indeed be just the females. The bovine species per se is dimorphic. Cattle did not originate as the term for bovine animals, it was borrowed from Anglo-Norman catel, itself from medieval Latin capitale'principal sum of money, capital', itself derived in turn from Latin caput'head'. Cattle meant movable personal property livestock of any kind, as opposed to real property; the word is a variant of chattel and related to capital in the economic sense. The term replaced earlier Old English feoh ` property', which survives today as fee; the word "cow" came via Anglo-Saxon cū, from Common Indo-European gʷōus = "a bovine animal", compare Persian: gâv, Sanskrit: go-, Welsh: buwch.
The plural cȳ became ki or kie in Middle English, an additional plural ending was added, giving kine, but kies and others. This is the origin of the now archaic English plural, "kine"; the Scots language singular is coo or cou, the plural is "kye". In older English sources such as the King James Version of the Bible, "cattle" refers to livestock, as opposed to "deer" which refers to wildlife. "Wild cattle" may refer to undomesticated species of the genus Bos. Today, when used without any other qualifier, the modern meaning of "cattle" is restricted to domesticated bovines. In general, the same words are used in different parts of the world, but with minor differences in the definitions; the terminology described here contrasts the differences in definition between the United Kingdom and other British-influenced parts of the world such as Canada, New Zealand and the United States. An "intact" adult male is called a bull. A wild, unmarked bull is known as a micky in Australia. An unbranded bovine of either sex is called a maverick in the Canada.
An adult female that has had a calf is a cow. A young female before she has had a calf of her own and is under three years of age is called a heifer. A young female that has had only one calf is called a first-calf heifer. Young cattle of both sexes are called calves until they are weaned weaners until they are a year old in some areas. After that, they are referred to as stirks if between one and two years of age. A castrated male is called a steer in the United States.