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52-464: As nematoceran flies, adult gnats have antennae with at least six segments that are often long and slender. They are generally slender-bodied with long and narrow wings. Black fly (Simuliidae) and biting midges (Ceratopogonidae), also belonging to the gnat category, are small, sometimes barely visible, blood-sucking flies commonly known in many areas as biting gnats, sand flies, punkies or " no-see-ums ", among other names. In general, gnats go through

104-542: A green or blue ground colour, while protoporphyrin IX produces reds and browns as a ground colour or as spotting. Non-passerines typically have white eggs, except in some ground-nesting groups such as the Charadriiformes , sandgrouse and nightjars , where camouflage is necessary, and some parasitic cuckoos which have to match the passerine host's egg. Most passerines, in contrast, lay coloured eggs, even if there

156-436: A longer fetal development. Comparatively anatomically simple animals will be able to go through the full development and leave the egg in a form reminiscent of the adult animal. This is the situation found in hagfish and some snails . Animals with smaller size eggs or more advanced anatomy will still have a distinct larval stage, though the larva will be basically similar to the adult animal, as in lampreys , coelacanth and

208-403: A naked egg cell. Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The yolk is concentrated in one part of the egg (the vegetal pole ), with the cell nucleus and most of the cytoplasm in the other (the animal pole ). The cell cleavage is uneven, and mainly concentrated in the cytoplasma-rich animal pole. The larger yolk content of the mesolecithal eggs allows for

260-414: A protective shell , either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark and

312-558: A reaction to a compound from the flies' salivary glands . Less common severe allergic reactions may require hospitalization. Repellents provide some protection against biting flies. Products containing the active ingredient ethyl butylacetylaminopropionate (IR3535), DEET ( N , N -diethyl- meta -toluamide), or picaridin are most effective. Some beauty products have been found effective, and their use as insect repellents have been approved by EPA (e.g., Skin So Soft ). However, given

364-523: A shell and would dry out in the air. Even air-breathing amphibians lay their eggs in water, or in protective foam as with the Coast foam-nest treefrog, Chiromantis xerampelina . Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one (as in condors ) to about 17 (the grey partridge ). Some birds lay eggs even when not fertilized (e.g. hens ); it

416-495: Is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote ) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches. Most arthropods , vertebrates (excluding live-bearing mammals ), and mollusks lay eggs, although some, such as scorpions , do not. Reptile eggs, bird eggs , and monotreme eggs are laid out of water and are surrounded by

468-414: Is known as oviparity , in which the female lays undeveloped eggs that are externally fertilized by a male. Typically large numbers of eggs are laid at one time (an adult female cod can produce 4–6 million eggs in one spawning) and the eggs are then left to develop without parental care. When the larvae hatch from the egg, they often carry the remains of the yolk in a yolk sac which continues to nourish

520-425: Is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs. Many animals feed on eggs. For example, principal predators of the black oystercatcher 's eggs include raccoons , skunks , mink , river and sea otters , gulls , crows and foxes . The stoat ( Mustela erminea ) and long-tailed weasel ( M. frenata ) steal ducks' eggs. Snakes of

572-416: Is no need of cryptic colors. However, some have suggested that the protoporphyrin markings on passerine eggs actually act to reduce brittleness by acting as a solid-state lubricant. If there is insufficient calcium available in the local soil, the egg shell may be thin, especially in a circle around the broad end. Protoporphyrin speckling compensates for this, and increases inversely to the amount of calcium in

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624-446: Is not uncommon for pet owners to find their lone bird nesting on a clutch of unfertilized eggs, which are sometimes called wind-eggs. The default colour of vertebrate eggs is the white of the calcium carbonate from which the shells are made, but some birds, mainly passerines , produce coloured eggs. The colour comes from pigments deposited on top of the calcium carbonate base; biliverdin and its zinc chelate , and bilirubin , give

676-643: Is sometimes reflected in the common name for the species. They feed in the daytime, preferably when wind speeds are low. Black flies may be either univoltine or multivoltine , depending on the species. The number of generations a particular pest species has each year tends to correlate with the intensity of human efforts to control those pests. Work conducted at Portsmouth University in 1986–1987 indicates Simulium spp. create highly acidic conditions within their midguts. This acidic environment provides conditions ideally suited to bacteria that metabolise cellulose. Insects cannot metabolise cellulose independently, but

728-408: Is thought to act as a shock absorber, protecting the calcite shell from fracture during incubation, such as colliding with other eggs in the nest. Most bird eggs have an oval shape , with one end rounded and the other more pointed. This shape results from the egg being forced through the oviduct . Muscles contract the oviduct behind the egg, pushing it forward. The egg's wall is still shapeable, and

780-399: Is usually motile whereas the female gamete cell, the ovum , is generally larger and sessile . The male and female gametes combine to produce the zygote cell. In multicellular organisms, the zygote subsequently divides in an organised manner into smaller more specialised cells, so that this new individual develops into an embryo . In most animals, the embryo is the sessile initial stage of

832-581: The Hessian fly larva, form galls in flowers, leaves, stems, roots or other plant parts. Some South American pleurothallid orchids are pollinated by tiny gnats and have correspondingly small flowers . Adult non-biting gnats do not damage plants but are considered a nuisance. Usually, larvae do not cause serious plant damage, but when present in large numbers can stunt the plant growth and damage its roots. To prevent gnats from spreading, measures have to be taken to target immature stages of development of

884-415: The coelacanths can reach a size of 9 cm (3.5 in) in diameter, and the young go through full development while in the uterus , living on the copious yolk. Animals are commonly classified by their manner of reproduction, at the most general level distinguishing egg-laying (Latin. oviparous ) from live-bearing (Latin. viviparous ). These classifications are divided into more detail according to

936-403: The maxillae and mandibles , cutting the skin and rupturing its fine capillaries. Feeding is facilitated by a powerful anticoagulant in the flies' saliva , which also partially numbs the site of the bite, reducing the host's awareness of being bitten and thereby extending the flies' feeding time. Biting flies feed during daylight hours only and tend to zero in on areas of thinner skin, such as

988-594: The planula , and either develops directly into the adult animals or forms new adult individuals through a process of budding . Microlecithal eggs require minimal yolk mass. Such eggs are found in flatworms , roundworms , annelids , bivalves , echinoderms , the lancelet and in most marine arthropods . In anatomically simple animals, such as cnidarians and flatworms, the fetal development can be quite short, and even microlecithal eggs can undergo direct development. These small eggs can be produced in large numbers. In animals with high egg mortality, microlecithal eggs are

1040-411: The salamanders . Eggs with a large yolk are called macrolecithal. The eggs are usually few in number, and the embryos have enough food to go through full fetal development in most groups. Macrolecithal eggs are only found in selected representatives of two groups: Cephalopods and vertebrates . Macrolecithal eggs go through a different type of development than other eggs. Due to the large size of

1092-451: The species . Physical tactics include eliminating favorable living conditions: reduction of excess moisture, drainage of pools with standing water, and removal of decaying organic matter. Commercially available control agents and insecticides can be used as a control measure, but are not recommended for use in a household. To control adult gnats in smaller areas, pressurized aerosol sprays with pyrethrins can be used. Other control measures in

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1144-426: The 18th century, the "Golubatz fly" ( Simulium colombaschense ) was a notorious pest in central Europe. Even non-biting clouds of black flies, whether composed of males or of species that do not feed on humans or do not require a blood meal before egg laying, can form a nuisance by swarming into orifices. Bites are shallow and accomplished by first stretching the skin using teeth on the labrum and then abrading it with

1196-774: The Americas ( S. callidum and S. metallicum in Central America, S. ochraceum in Central and South America). Eggs are laid in running water, and the larvae attach themselves to rocks. Breeding success is highly sensitive to water pollution. The larvae use tiny hooks at the ends of their abdomens to hold on to the substrate, using silk holdfasts and threads to move or hold their place. They have foldable fans surrounding their mouths, also termed "mouth brushes". The fans expand when feeding, catching passing debris (small organic particles, algae, and bacteria). The larva scrapes

1248-413: The adult body, and by the yolk which the egg provides to nourish the embryo. Vertebrate eggs can be classified by the relative amount of yolk . Simple eggs with little yolk are called microlecithal , medium-sized eggs with some yolk are called mesolecithal , and large eggs with a large concentrated yolk are called macrolecithal . This classification of eggs is based on the eggs of chordates , though

1300-540: The air. Often the sex of the developing embryo is determined by the temperature of the surroundings, with cooler temperatures favouring males. Not all reptiles lay eggs; some are viviparous ("live birth"). Dinosaurs laid eggs, some of which have been preserved as petrified fossils. Among mammals, early extinct species laid eggs, as do platypuses and echidnas (spiny anteaters). Platypuses and two genera of echidna are Australian monotremes . Marsupial and placental mammals do not lay eggs, but their unborn young do have

1352-407: The basic principle extends to the whole animal kingdom . Small eggs with little yolk are called microlecithal. The yolk is evenly distributed, so the cleavage of the egg cell cuts through and divides the egg into cells of fairly similar sizes. In sponges and cnidarians , the dividing eggs develop directly into a simple larva, rather like a morula with cilia . In cnidarians, this stage is called

1404-492: The biological sense. In placental mammals , the egg itself is void of yolk, but develops an umbilical cord from structures that in reptiles would form the yolk sac. Receiving nutrients from the mother, the fetus completes the development while inside the uterus. Eggs are common among invertebrates , including insects , spiders , mollusks , and crustaceans . All sexually reproducing life, including both plants and animals, produces gametes . The male gamete cell, sperm ,

1456-404: The cells of incipient multicellular organisms. The cycle of the egg's formation is started by the gamete ovum being released ( ovulated ) and egg formation being started. The finished egg is then ovipositioned and eventual egg incubation can start. Scientists often classify animal reproduction according to the degree of development that occurs before the new individuals are expelled from

1508-401: The complex tissues that identify amniotes. The eggs of the egg-laying mammals (the platypus and the echidnas ) are macrolecithal eggs very much like those of reptiles . The eggs of marsupials are likewise macrolecithal, but rather small, and develop inside the body of the female, but do not form a placenta . The young are born at a very early stage, and can be classified as a " larva " in

1560-476: The crowded cliff ledges on which they breed. Yolks of birds' eggs are yellow from carotenoids , it is affected by their living conditions and diet. Bird eggshells are diverse. For example: Tiny pores in bird eggshells allow the embryo to breathe. The domestic hen 's egg has around 7000 pores. Some bird eggshells have a coating of vaterite spherules , which is a rare polymorph of calcium carbonate. In Greater Ani Crotophaga major this vaterite coating

1612-740: The fan's catch into its mouth every few seconds. Black flies depend on lotic habitats to bring food to them. They will pupate under water and then emerge in a bubble of air as flying adults. They are often preyed upon by trout during emergence. The larva of some South African species are known to be phoretic on mayfly nymphs. Adult males feed on nectar, while females exhibit anautogeny and feed on blood before laying eggs. Some species in Africa can range as far as 40 mi (64 km) from aquatic breeding sites in search of their blood meals, while other species have more limited ranges. Different species prefer different host sources for their blood meals, which

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1664-1154: The four life stages of egg, larva, pupa and adult, similar to other flies. The fungus gnats lay their eggs in moist organic debris or soil, which hatch into larvae. The larvae feed on organic matter such as leaf mold, mulch, compost, grass clippings, root hairs and fungi. They eventually become pupae and then adults emerge from the pupae. At a temperature of 75 °F (23.9 °C), the cycle takes approximately 17 days: 3 days as eggs, 10 days as larvae and 4 days as pupae. Warmer temperatures allow more rapid development. Some species of fungus gnats (e.g. those in genus Bradysia ) are pests of mushrooms and roots of plants in greenhouses . Other gnats begin their lives as eggs laid in masses in water, or laid on aquatic plants. The aquatic larvae dwell in ponds, pools, water-filled containers, clogged rain gutters or wet soil, which generally feed on plant matter (living or dead). The larvae develop into pupae and then into adults. Adults live only long enough to reproduce and they may form large mating swarms , often around dusk. The life cycle generally takes 4-5 weeks. The larvae of most gall gnats ( Cecidomyiidae ), such as

1716-650: The genera Dasypeltis and Elachistodon specialize in eating eggs. Brood parasitism occurs in birds when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include the cowbirds and many Old World cuckoos . Like amphibians, amniotes are air-breathing vertebrates , but they have complex eggs or embryos , including an amniotic membrane . Amniotes include reptiles (including dinosaurs and their descendants, birds) and mammals. Reptile eggs are often rubbery and are always initially white. They are able to survive in

1768-787: The household can include turning off unnecessary lights at dusk and sealing vents and other openings. Black fly Genera [REDACTED] Data related to Black fly at Wikispecies A black fly or blackfly (sometimes called a buffalo gnat , turkey gnat , or white socks ) is any member of the family Simuliidae of the Culicomorpha infraorder . It is related to the Ceratopogonidae , Chironomidae , and Thaumaleidae . Over 2,200 species of black flies have been formally named, of which 15 are extinct. They are divided into two subfamilies: Parasimuliinae contains only one genus and four species; Simuliinae contains all

1820-494: The individual life cycle, and is followed by the emergence (that is, the hatching) of a motile stage. The zygote or the ovum itself or the sessile organic vessel containing the developing embryo may be called the egg. A recent proposal suggests that the phylotypic animal body plans originated in cell aggregates before the existence of an egg stage of development . Eggs, in this view, were later evolutionary innovations , selected for their role in ensuring genetic uniformity among

1872-411: The larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a critical point after which they must learn how to hunt and feed or they will die. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized and develop internally. However, the larvae still grow inside the egg consuming the egg's yolk and without any direct nourishment from

1924-465: The limited effectiveness of repellents, protecting oneself against biting flies requires taking additional measures, such as avoiding areas inhabited by the flies, avoiding peak biting times, and wearing heavy-duty, light-colored clothing, including long-sleeve shirts, long pants and hats. When black flies are numerous and unavoidable, netting that covers the head, like the “bee bonnets” used by beekeepers, can provide protection. Black flies are central to

1976-418: The mother also providing direct nourishment. The eggs of fish and amphibians are jellylike. Cartilaginous fish (sharks, skates, rays, chimaeras) eggs are fertilized internally and exhibit a wide variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them. These eggs do not have

2028-432: The mother. The mother then gives birth to relatively mature young. In certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mother's body. This is known as intrauterine cannibalism . In certain scenarios, some fish such as the hammerhead shark and reef shark are viviparous , with the egg being fertilized and developed internally, but with

2080-399: The nape of the neck or ears and ankles. Itching and localized swelling and inflammation sometimes result from a bite. Swelling can be quite pronounced depending on the species and the individual's immune response, and irritation may persist for weeks. Intense feeding can cause "black fly fever", with headache, nausea, fever, swollen lymph nodes, and aching joints; these symptoms are probably

2132-421: The norm, as in bivalves and marine arthropods. However, the latter are more complex anatomically than e.g. flatworms, and the small microlecithal eggs do not allow full development. Instead, the eggs hatch into larvae , which may be markedly different from the adult animal. In placental mammals, where the embryo is nourished by the mother throughout the whole fetal period, the egg is reduced in size to essentially

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2184-413: The pointed end develops at the back. . One hypothesis is that long, pointy eggs are an incidental consequence of having a streamlined body typical of birds with strong flying abilities; flight narrows the oviduct, which changes the type of egg a bird can lay. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait

2236-555: The presence of these bacteria allows cellulose to be metabolised into basic sugars. This provides nutrition to the black fly larvae, as well as the bacteria. This symbiotic relationship indicates a specific adaptation, as fresh-flowing streams could not provide sufficient nutrition to the growing larva in any other way. Only four genera in the family Simuliidae, Simulium , Prosimulium , Austrosimulium , and Cnephia , contain species that feed on people, though other species prefer to feed on other mammals or on birds . Simulium ,

2288-502: The rest. Over 1,800 of the species belong to the genus Simulium . Most black flies gain nourishment by feeding on the blood of mammals, including humans, although the males feed mainly on nectar . They are usually small, black or gray, with short legs and antennae . They are a common nuisance for humans, and many U.S. states have programs to suppress the black fly population. They spread several diseases, including river blindness in Africa ( Simulium damnosum and S. neavei ) and

2340-568: The small size of the eggs does not allow for direct development, and the eggs hatch to a larval stage ("fry"). In terrestrial animals with macrolecithal eggs, the large volume to surface ratio necessitates structures to aid in transport of oxygen and carbon dioxide, and for storage of waste products so that the embryo does not suffocate or get poisoned from its own waste while inside the egg, see amniote . In addition to bony fish and cephalopods, macrolecithal eggs are found in cartilaginous fish , reptiles , birds and monotreme mammals. The eggs of

2392-549: The smallest known bird egg, which measures between 6.35–11.4 millimetres (0.250–0.449 in) long and weighs half of a gram (around 0.02 oz). Some eggs laid by reptiles and most fish, amphibians, insects, and other invertebrates can be even smaller. Reproductive structures similar to the egg in other kingdoms are termed " spores ", or in spermatophytes " seeds ", or in gametophytes "egg cells". Several major groups of animals typically have readily distinguishable eggs. The most common reproductive strategy for fish

2444-416: The soil. For the same reason, later eggs in a clutch are more spotted than early ones as the female's store of calcium is depleted. The color of individual eggs is also genetically influenced, and appears to be inherited through the mother only, suggesting that the gene responsible for pigmentation is on the sex-determining W chromosome (female birds are WZ, males ZZ). It used to be thought that color

2496-503: The transmission of the parasitic nematode Onchocerca volvulus which causes onchocerciasis , or "river blindness", which is endemic in parts of South America , Africa , and the Arabian Peninsula . It serves as the larval host for the nematode and acts as the vector by which the disease is spread. The parasite lives on human skin and is transmitted to the black fly during feeding. Egg (biology) An egg

2548-417: The type genus, is the most widespread and is a vector for several diseases, including river blindness . Mature adults can disperse tens or hundreds of miles from their breeding grounds in fresh flowing water, under their own power and assisted by prevailing winds, complicating control efforts. Swarming behavior can make outdoor activities unpleasant or intolerable, and can affect livestock production. During

2600-432: The yolk, the cell division can not split up the yolk mass. The fetus instead develops as a plate-like structure on top of the yolk mass, and only envelopes it at a later stage. A portion of the yolk mass is still present as an external or semi-external yolk sac at hatching in many groups. This form of fetal development is common in bony fish , even though their eggs can be quite small. Despite their macrolecithal structure,

2652-442: Was 30 cm × 14 cm × 9 cm (11.8 in × 5.5 in × 3.5 in) in size. Whale shark eggs typically hatch within the mother. At 1.5 kg (3.3 lb) and up to 17.8 cm × 14 cm (7.0 in × 5.5 in), the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some non-avian dinosaurs laid larger eggs. The bee hummingbird produces

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2704-456: Was applied to the shell immediately before laying, but subsequent research shows that coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there is a lack of that mineral. In species such as the common guillemot , which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on

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