The flea can lay up to 50 eggs per day and around 500 in it's life span.
The cat flea, Ctenocephalides felis, is one of the most abundant and widespread species of flea on Earth.
The cat flea is a small, sucking, insect of the order Siphonoptera. Adults range from 1–2 mm long and are usually a reddish-brown colour, although this can vary. The cat flea, and all other fleas, are compressed laterally, resulting in an extremely thin insect that can be quite hard to find in an animal's coat. The cat flea's primary host is the domestic cat, but the cat flea is also the primary flea infesting dogs in most of the world. The cat flea can also maintain its life cycle on other carnivores and on omnivores. Humans can be bitten, though a long-term population of cat fleas cannot be sustained and infest people. However, if the female flea is allowed to feed for twelve consecutive hours on a human, it can lay viable eggs.
The female cat flea lays her eggs on the host, but the eggs, once dry, have evolved to filter out of the haircoat of the host into the resting and sheltering area of the host.
The eggs hatch into larvae, which are negatively phototaxic, meaning that they hide from light in the substrate. Flea larvae feed on a variety of organic substances, but most importantly subsist on dried blood that is filtered out of the haircoat of the host after it is deposited there as adult flea fecal material. Thus the adult population on the host feeds the larval population in the host's environment.
Flea larvae metamorphose through 4 stages before spinning a cocoon and entering the pupal stage. The pupal stage varies greatly in length; the pre-emergent flea does not normally emerge as a young adult flea until the presence of a potential host is perceived by warmth or vibration. Newly emerged fleas are stimulated to jump to a new host within seconds of emerging from the cocoon. The new flea begins feeding on host blood within minutes.
A few fleas on adult dogs or cats cause little harm unless the host becomes allergic to substances in saliva. The disease that results is called flea allergy dermatitis. Small animals with large infestations can lose enough bodily fluid to fleas feeding that dehydration may result. Cat fleas also may be responsible for disease transmission through humans, and have been suspected as transmission agents of plague.
Cat fleas can transmit other parasites and infections to dogs and cats and also to humans. The most prominent of these are Bartonella, murine typhus, and apedermatitis. The tapeworm Dipylidium caninum can be transmitted when an immature flea is swallowed by pets or humans. In addition, cat fleas have been found to carry Borrelia burgdorferi, the etiologic agent of Lyme disease, but their ability to transmit the disease is unclear.
Fleas are the insects forming the order Siphonaptera. They are wingless, with mouthparts adapted for piercing skin and sucking blood. Fleas are external parasites, living by hematophagy off the blood of mammals and birds.
Some flea species include:
Over 2,000 species have been described worldwide.
Fleas are wingless insects (1/16 to 1/8-inch (1.5 to 3.3 mm) long) that are agile, usually dark colored (for example, the reddish-brown of the cat flea), with tube-like mouth-parts adapted to feeding on the blood of their hosts. Their legs are long, the hind pair well adapted for jumping: a flea can jump vertically up to 7 inches (18 cm) and horizontally up to 13 inches (33 cm), making the flea one of the best jumpers of all known animals (relative to body size), second only to the froghopper. According to an article in Science News, "researchers with the University of Cambridge in England have shown that fleas take off from their tibiae and tarsi—the insect equivalent of feet—and not their trochantera, or knees. The researchers report their conclusion in the March 1 Journal of Experimental Biology." It has been known that fleas do not use muscle power but energy stored in a protein named resilin but the researchers used high-speed video technology and mathematical models to discover where the spring action actually happens. Their bodies are laterally compressed, permitting easy movement through the hairs or feathers on the host's body (or in the case of humans, under clothing). The flea body is hard, polished, and covered with many hairs and short spines directed backward, which also assist its movements on the host. The tough body is able to withstand great pressure, likely an adaptation to survive attempts to eliminate them by mashing or scratching. Even hard squeezing between the fingers is normally insufficient to kill a flea. It is possible to eliminate them by pressing individual fleas with adhesive tape or softened beeswax (or "cheese" wax) or by rolling a flea briskly between the fingers to disable it then crushing it between the fingernails. Fleas also can be drowned in soapy water.
Fleas lay tiny white oval-shaped eggs better viewed through a loupe. The larva is small, pale, has bristles covering its worm-like body, lacks eyes, and has mouthparts adapted to chewing. The larvae feed on various organic matter, especially the feces of mature fleas. The adult flea's diet consists solely of fresh blood. In the pupa phase, the larva is enclosed in a silken, debris-covered cocoon.
Fleas are holometabolous insects, going through the four life cycle stages of egg, larva, pupa, and imago (adult). Adult fleas must feed on blood before they can become capable of reproduction.
The flea life cycle begins when the female lays after feeding. Eggs are laid in batches of up to 20 or so, usually on the host itself, which means that the eggs can easily roll onto the ground. Because of this, areas where the host rests and sleeps become one of the primary habitats of eggs and developing fleas. The eggs take around two days to two weeks to hatch.
Flea larvae emerge from the eggs to feed on any available organic material such as dead insects, feces, and vegetable matter. They are blind and avoid sunlight, keeping to dark places like sand, cracks and crevices, and bedding. Given an adequate supply of food, larvae should pupate and weave a silken cocoon within 1–2 weeks after 3 larval stages. After another week or two, the adult flea is fully developed and ready to emerge from the cocoon. They may however remain resting during this period until they receive a signal that a host is near - vibrations (including sound), heat, and carbon dioxide are all stimuli indicating the probable presence of a host. Fleas are known to overwinter in the larval or pupal stages.
Once the flea reaches adulthood, its primary goal is to find blood and then to reproduce. Flea populations are evenly distributed, with about 50% eggs, 35% larvae, 10% pupae, and 5% adults. Their total life span can be as short as one year, but may be several years in ideal conditions. Female fleas can lay 5000 or more eggs over their life, allowing for phenomenal growth rates. Average (30-90 days). A flea might live a year and a half under ideal conditions. These include the right temperature, food supply, and humidity. Generally speaking, though, an adult flea only lives for 2 or 3 months. Without a host for food, a flea's life might be as short as a few days. But with ample food supply, the adult flea will often live up to 100 days.
Adult female rabbit fleas, Spilopsyllus cuniculi, can detect the changing levels of cortisol and corticosterone, hormones in the rabbit's blood that indicate she is getting close to giving birth. This triggers sexual maturity in the fleas and they start producing eggs. As soon as the baby rabbits are born, the fleas make their way down to them and once on board they start feeding, mating, and laying eggs. After 12 days, the adult fleas make their way back to the mother. They complete this mini-migration every time she gives birth.
Newly emerged adult fleas live only about one week if a blood meal is not obtained. However, completely developed adult fleas can live for several months without eating, so long as they do not emerge from their puparia. Optimum temperatures for the flea's life cycle are 70°F to 85°F (21°C to 30°C) and optimum humidity is 70%.
In the past, it was most commonly supposed that fleas had evolved from the flies (Diptera), based on similarities of the larvae. (Some authorities use the name Aphaniptera because it is older, but names above family rank need not follow the ICZN rules of priority, so most taxonomists use the more familiar name). Genetic and morphological evidence indicates that they are descendants of the Scorpionfly family Boreidae, which are also flightless; accordingly it is possible that they will eventually be reclassified as a suborder within the Mecoptera. Their evolution continued to produce adaptations for their specialized parasitic niche, such that they now have no wings and their eyes are covered over. The large number of flea species may be attributed to the wide variety of host species they feed on, which provides so many specific ecological niches to adapt to. In any case, all these groups seem to represent a clade of closely related insect lineages, for which the names Mecopteroidea and Antliophora have been proposed.
Flea systematics are not entirely fixed. While, compared to many other insect groups, fleas have been studied and classified fairly thoroughly, details still remain to be learned about the evolutionary relationships among the different flea lineages.
Fleas attack a wide variety of warm-blooded vertebrates including dogs, cats, humans, chickens, rabbits, squirrels, rats, ferrets, and mice.
Fleas are a nuisance to their hosts, causing an itching sensation which in turn may result in the host attempting to remove the pest by biting, pecking, scratching, etc. in the vicinity of the parasite. Fleas are not simply a source of annoyance, however. Flea bites generally result in the formation of a slightly raised, swollen itching spot with a single puncture point at the center (similar to a mosquito bite). The bites often appear in clusters or lines of two bites, and can remain itchy and inflamed for up to several weeks afterwards. Fleas can also lead to hair loss as a result of frequent scratching and biting by the animal, and can cause anemia in extreme cases.:126
Besides the problems posed by the creature itself, fleas can also act as a vector for disease. Fleas transmit not only a variety of viral, bacterial and rickettsial diseases to humans and other animals, but also protozoans and helminths.:72–73
Fleas that specialize as parasites on specific mammals may use other mammals as hosts; therefore humans are susceptible to the predation of more than one species of flea.
A misconception concerning the carrying/transmission of the HIV/AIDS by fleas has been debunked by the Centers for Disease Control and Prevention (CDC 2003), which stated that fleas cannot carry the virus and spread it to other humans.
Fleas can settle in a person's hair in less than ten minutes, causing soreness and itching. The itching associated with flea bites can be treated with anti-itch creams, usually antihistamines or hydrocortisone. Calamine lotion has been shown to be effective for itching.
Modern flea control is approached using Integrated Pest Management (IPM) protocols at the host (pet) level. IPM is achieved by targeting fleas during at least two separate life stages, with at least two separate molecules. This is typically achieved using an adulticide to kill adult fleas and an insect development inhibitor (IDI), like lufenuron, or insect growth regulator (IGR), like methoprene, to prevent development of immature stages. Flea adults, larvae, or eggs can be controlled with insecticides. Lufenuron is a veterinary preparation (known as Program) that attacks the larval flea's ability to produce chitin, necessary for the adult's hard exoskeleton, but does not kill fleas. Flea medicines need to be used with care because many of them also affect mammals.
Flea and tick ointment is hazardous to humans; the label of a commercial preparation warns: “First aid: If on skin or clothing, take off contaminated clothing, rinse skin immediately with plenty of water for 15 – 20 minutes; call a poison control center or doctor for treatment advice. . . Although (the product is) applied only between the shoulder blades and at the base of the tail, the dog’s skin and hair oils carry the product over the entire body . . . Wash thoroughly with soap and water after handling . . .”
Cedar oil, a non-toxic natural substance, has been proven effective in the eradication of infestations in pets.] [
Since more than three-quarters of a flea's life is spent somewhere other than on the host animal, it is not adequate to treat only the host; it is important also to treat the host's environment. Thorough vacuuming, washing linens in hot water, and treating all hosts in the immediate environment (the entire household, for example) are essential and if possible on a regular basis.
Contemporary commercial products for the topical treatment of flea infestations on pets contain pesticides such as imidacloprid, permethrin, and (S)-methoprene. All flea control products are recommended to be used at least half-yearly because the life cycle of flea and tick can last to up to 6 months, and by using one of the flea and tick control products for so long, the infestation is highly prevented and, in the end, stopped. Although all these products are effective in fighting against flea and tick infestations, they have different active ingredients and, because cats cannot metabolize some of the compounds of the product, care must be taken in their use.
Combatting a flea infestation in the home takes patience because for every flea found on an animal, there could be many more developing in the home. A spot-on insecticide will kill the fleas on the pet and in turn the pet itself will be a roving flea trap and mop up newly hatched fleas. The environment should be treated with a fogger or spray insecticide containing an insect growth regulator, such as pyriproxyfen or methoprene to kill eggs and pupae, which are quite resistant against insecticides. Frequent vacuuming is also helpful, but the vacuum bag must be disposed of or sealed immediately afterwards to prevent further infestation.
Diatomaceous earth can also be used as a home flea treatment in lieu of acetylcholinesterase inhibitory treatments or insecticides which carry with them a risk of poisoning for both humans and other animals. However, Diatomaceous earth is at least potentially dangerous to pets and people when inhaled, so care in use is recommended. Application is effective on both the interior and exterior of one's property, but the efficacy of Diatomaceous earth is diminished when introduced to water. Because Diatomaceous earth is commonly available in food grade quality, it is also possible to leave it exposed in areas typically vulnerable to fleas and other insects.
Bathing can dramatically reduce the flea population on a badly-infested animal, especially when in combination with a mild detergent or shampoo, and brushing or combing. Fleas are susceptible to drowning, but generally survive in air pockets in the animal's undercoat. However, use of shampoo or mild detergent such as manual dish soap will reduce the surface tension of the water, allowing it to soak in more deeply, and brushing or combing the fur during the bath can also push the water more deeply into the fur.
Baking Soda is also used to kill via dehydration, it's available in large amounts as a food grade material and safe for family and pets when used inside the home (carpets and floors) a layer can be sprinkled onto a carpet and worked into the fibers down to where the larvae and eggs are to dehydrate and kill them. It can be easily vacuumed up afterwards with safe disposal... often multiple weekly treatments will be required to remove an infestation completely.
Table salt can also be used inside the home in the same way as, or in combination with, baking soda as a low cost and safe method of breaking their life cycle. Pulverizing or grinding the salt with a coffee grinder will make it more affective as it will stick to the flea, killing it quicker through dehydration.
Dried pennyroyal has been suggested as a natural flea control, but is not recommended in homes with pets due to its high toxicity to mammals.
Borax is sold as a "Natural Laundry Booster" and can also be used as another home treatment for flea infestations. Borax contains sodium borate which kills fleas by dehydrating them, but its safety for pets is untested.
Dehumidifiers with air conditioning and vacuuming all may interrupt the flea life cycle.
A combination of controlled humidity, temperature, and vacuumingshould eliminate fleas from an environment. Altering even one of these environmental factors may be enough to drastically lower and eliminate an infestation.
Vacuuming on a frequent basis, not only the places where the pet lies, but extensively, is particularly effective.
A laboratory study done at the University of California showed that vacuuming catches about 96% of adult fleas.
In arid areas, less than 5% of flea eggs complete the life-cycle. Because Humidity is critical to flea survival, Eggs need relative humidity of at least 70–75% to hatch, and larvae need at least 50% humidity to survive. In humid areas, about 20% of the eggs survive to adulthood.
Lower temperatures slow down or completely interrupt the flea life-cycle. Fleas thrive at higher temperatures, but need 70° to 90°F (21° to 32°C) to survive.
Homemade flea traps work well to catch fleas in the dark. Place a desk lamp over a white bowl of dish soap water overnight. The fleas, attracted to the bright warm light, jump into the soapy water and immediately drown.
helm, arth (acar)
helm, arth (lice), zoon
In zoology, an egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg (Latin, ovum) is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing embryo can survive on its own. The term "egg" is used differently outside the animal kingdom, for an egg cell (sometimes called an ovum). Reproductive structures similar to the egg in other kingdoms are termed spores, or (in spermatophytes) seeds.
Oviparous animals are animals that lay eggs, with little or no other development within the mother. The study or collecting of eggs, particularly bird eggs, is called oology.
Reptile eggs, bird eggs, and monotreme eggs, which are laid out of water, are surrounded by a protective shell, either flexible or inflexible. The special membranes that support these eggs are traits of all amniotes, including mammals.
Eggs laid on land or in nests are usually kept within a favourable temperature range (warm) while the embryo grows. When the embryo is adequately developed it breaks out of the egg's shell. This breaking out is known as hatching. Baby animals which have just hatched are hatchlings, though standard names for babies of particular species continue to apply, such as chick for a baby chicken. Some embryos have a temporary egg tooth with which to crack, pip, or break the eggshell or covering.
The 1.5 kg (3.3 lb) ostrich egg is the largest egg currently known, though the extinct Aepyornis and some dinosaurs had larger eggs. The Bee Hummingbird produces the smallest known bird egg, which weighs half of a gram. The eggs laid by some reptiles and most fish can be even smaller, and those of insects and other invertebrates can be much smaller still.
Several major groups of animals typically have readily distinguishable eggs.
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 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 color of vertebrate eggs is the white of the calcium carbonate from which the shells are made, but some birds, mainly passerines, produce colored eggs. The pigments biliverdin and its zinc chelate give a green or blue ground color, and protoporphyrin produces reds and browns as a ground color 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 colored eggs, even if there 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 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 was applied to the shell immediately before laying, but this 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 the crowded cliff ledges on which they breed.
Bird eggshells are diverse. For example:
Tiny pores in bird eggshells allow the embryo to breathe. The domestic hen's egg has around 7500 pores.
Most bird eggs have an oval shape, with one end rounded (the aerus) and the other more pointed (the taglion). 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 the pointy end develops at the back. 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 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 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.
An average Whooping Crane egg is 102 mm (4.0 in) long and weighs 208 g (7.3 oz)
Eurasian oystercatcher eggs camouflaged in the nest
Egg of a Senegal Parrot, a bird that nests in tree holes, on a 1 cm (0.39 in) grid
Eggs of ostrich, emu, kiwi and chicken
Finch egg next to American dime
Eggs of duck, goose, guineafowl and chicken
Eggs of ostrich, cassowary, chicken, flamingo, pigeon and blackbird
Egg of an emu
The most common reproductive strategy for fish 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 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 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 rare scenarios, some fish such as the hammerhead shark and reef shark are viviparous, with the egg being fertilized and developed internally, but with the mother also providing direct nourishment.
The eggs of fish and amphibians are jellylike. Cartilagenous 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 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.
The eggs of the egg-laying mammals (the platypus and the spiny anteaters) 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 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, 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 the individual life cycle, and is followed by the emergence (that is, the hatching) of a motile stage. The zygote, the sessile organic vessel containing the developing embryo, or even the ova itself may be called the egg.
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 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 the complex tissues that identify amniotes.
Scientists often classify animal reproduction by degree of development that occurs before the new individuals are expelled from the adult body, and eggs by the degree of yolk they include.
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 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 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 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 egg is nourished from the mother throughout the whole fetal period, the egg is reduced in size to essentially a naked egg cell (zygote).
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 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 the salamanders.
Eggs with a large yolk are called macrolecithal. The eggs are usually few in number, and the embryo have enough food to go through a full fetal development in most groups. Really macrolecithal eggs are only found in selected representatives from two groups: Cephalopods and vertebrates.
Macrolecithal eggs go through a different type of development than other eggs. Due to the large size of 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 envelope 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, the small size of the eggs do not allow for direct development, and the eggs hatches to a larval stage ("fry"). In terrestrial animals with macrolecithal eggs, the large volume to surface ratio necessitate structures to aid in transport of oxygen and carbon dioxide, and for storage of waste products so that the embryo do not suffocate or get poisoned from its own waste while inside the egg, see amniote.
In addition to bony fish and cephalopods, macrolecital eggs are found in cartilaginous fish, reptiles, birds and monotreme mammals. The eggs of the coelacanths can reach a size of 9 cm in diameter, and the young go through full development while in the uterus, living off 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 the development that occurs before the offspring are expelled from the adult's body. Traditionally:
Eggs laid by many different species, including birds, reptiles, amphibians, and fish, have probably been eaten by mankind for millennia. Popular choices for egg consumption are chicken, duck, roe, and caviar, but by a wide margin the egg most often humanly consumed is the chicken egg, typically unfertilized.
According to the Kashrut, that is the set of Jewish dietary laws, kosher food may be consumed according to halakha (Jewish law). Kosher meat and milk (or derivatives) cannot be mixed (Deuteronomy 14:21) or stored together. Eggs are considered pareve (neither meat nor dairy) despite being an animal product and can be mixed with either milk or kosher meat. Mayonnaise, for instance, is usually marked "pareve" despite by definition containing egg.
Many vaccines for infectious diseases are produced in fertile chicken eggs. The basis of this technology was the discovery in 1931 by Alice Miles Woodruff and Ernest William Goodpasture at Vanderbilt University that the rickettsia and viruses that cause a variety of diseases will grow in chicken embryos. This enabled the development of vaccines against influenza, chicken pox, smallpox, yellow fever, typhus, Rocky mountain spotted fever and other diseases.
A baby tortoise emerges from its egg.
Insect eggs, in this case those of the Emperor Gum Moth, are often laid on the underside of leaves.
Fish eggs, such as these herring eggs are often transparent and fertilized after laying.
Skates and some sharks have a uniquely shaped egg case called a mermaid's purse.
A clutch of eggs refers to all the eggs produced by birds, amphibians, or reptiles, often at a single time, particularly those laid in a nest.
In birds, destruction of a clutch by predators, (or removal by humans, for example the California Condor breeding program), results in double-clutching. The technique is used to double the production of a species eggs, in the California Condor case, specifically to increase population size. The act of putting one's hand in a nest to remove eggs is known as dipping the clutch.
Clutch size differs greatly between species, sometimes even within the same genus. It may also differ within the same species due to many factors including habitat, health, nutrition, predation pressures, and time of year. Clutch size variation can also reflect variation in optimal reproduction effort. Long-lived species tend to have smaller clutch sizes than short-lived species (see also r/K selection theory). The evolution of optimal clutch size is also driven by other factors, such as parent-offspring conflict.
Clutch size recorded in ornithological field notes may or may not include lost or broken eggs.
Mallard (Anas platyrhynchos), very large clutch or possibly from two females
Great Black-backed Gull (Larus marinus), small clutch
Masked Lapwing (Vanellus miles), typical clutch
Common Moorhen (Gallinula chloropus), small clutch
Lesser Spotted Eagle (Aquila pomarina), typical clutch
Feral Pigeon (Columba livia domestica), typical clutch
European Starling (Sturnus vulgaris), typical clutch
European Goldfinch (Carduelis carduelis), large clutch
Northern dusky salamander (Desmognathus fuscus), typical egg clutch
The dog flea (Ctenocephalides canis) is a species of flea that lives as a ectoparasite on a wide variety of mammals, particularly the domestic dog and cat. It closely resembles the cat flea, Ctenophalides felis, which can live on a wider range of animals and is generally more prevalent worldwide.
The dog flea is troublesome because it can spread Dipylidium caninum.
Although they feed on the blood of dogs and cats, they sometimes bite humans. They can live without food for several months, but females must have a blood meal before they can produce eggs. They can deliver about 4000 eggs on the host's fur. The eggs go through four lifecycle stages: embryo, larva, pupa, and imago (adult). This whole life cycle from egg to adult takes from two to three weeks, although this depends on the temperature. It may take longer in cool conditions.
The dog flea's mouthparts are adapted for piercing skin and sucking blood. Dog fleas are external parasites, living by hematophagy off the blood of dogs. The dog often experiences severe itching in all areas where the fleas may reside.
Fleas do not have wings and their hard bodies are flattened from side-to-side and have hairs and spines, which makes it easy for them to travel through hair. They have relatively long hind legs for jumping.
The dog flea can be distinguished from the very similar cat flea by its head, which is anteriorly rounded rather than elongate, and the tibiae of its hind legs, which exhibit eight setae-bearing notches rather than six.
Flea infestations can be not only annoying for both dogs and cats and humans, but also very dangerous. Problems caused by fleas may range from mild to severe itching and discomfort to skin problems and infections. Anemia may also result from flea bites in extreme circumstances. Furthermore, fleas can transmit tapeworms and diseases to pets.
When fleas bite humans, they may develop an itching rash with small bumps that may bleed. This rash is usually located on the armpit or fold of a joint such as the elbow, knee, or ankle. When the area is pressed, it turns white.
When dogs are troubled by fleas, they scratch and bite themselves, especially in areas such as the head, neck, and around the tail. Fleas normally concentrate in such areas. This incessant scratching and biting may cause the dog's skin to become red and inflamed.
Flea allergy dermatitis is developed by those dogs allergic to flea saliva. In this case, the symptoms previously mentioned are more pronounced. Because of compulsive scratching and biting, the dog may lose hair, get bald spots, exhibit hot spots due to extreme irritation, and develop infections that result in smelly skin.
Preventing and controlling flea infestations is a multistep process. Prevention in the case of flea infestations can sometimes be difficult, but is the most effective way to ensure the dog will not get reinfected. Controlling flea infestations implies not only the pet has been cured and the fleas living on it are killed, but also that the environment in which the pet lives is free of these parasites. And from all these, removing the fleas from the pet is maybe the easiest and simplest step given the many products especially designed to kill fleas available on the market.
Every female flea on the pet is likely to have laid eggs in the environment in which the pet lives. Therefore, effective prevention and control of flea infestations implies having removed the fleas from both indoor and outdoor environments, from all pets, and keeping immature forms of fleas from developing.
Removing the fleas in indoor environments mainly consists of removing them mechanically. This can be done by a thorough vacuuming, especially in places where fleas are more likely to be found, such as below drapes, the place where the pet sleeps, and under furniture edges. Vacuuming can remove an estimated 50% of flea eggs. After vacuuming, using a specially designed product is recommended to kill the remaining fleas and to stop the development of eggs and larvae. The products available on the market may include carpet powders, sprays or foggers, which contain adult insecticides and insect growth regulators.
Special attention should be paid to the dog's bedding. This should be washed every week; also the bed and surrounding areas should be treated with adult insecticides and insect growth regulators. Cleaning should be done at the same time in the cars, garage, pet carrier, basement, or any other place where the dog is known to spend time.
Preventing flea infestations must include eliminating the parasites from the yard or kennel areas, the two places where fleas are most likely to occur. Dog houses, patios or porches are some of the outdoor areas in which it is more likely to find fleas and those should be thoroughly cleaned. Fleas can also be carried by wild animals, such as opossums, chipmunks and raccoons. One is recommended to discourage these wild animals from their property and pets by never feeding them.
Removing fleas from the pets is not a difficult task considering the advent of products which are designed not only to kill fleas, but also to offer protection from further infestations. Flea-control products are available in once-a-month topicals, dog collars, sprays, dips, powders, shampoos, and injectable and oral products. All these products contain an insecticide as an active ingredient which kills the fleas when coming into contact with them. Fleas absorb the insecticide which either paralyzes them or kills them.
A very important part of flea prevention is to persist with the same control measures for as long as possible. Though the cleaning process was successful, fleas in incipient stages likely still exist around the house or on the pet. The lifecycle of fleas can take up to six months, so maintaining the prevention measures for as long as half a year is recommended.
To effectively get rid of fleas and flea eggs, one should treat not only dogs, but also the household and exterior regions to eliminate eggs from bedding, grass, floor, furniture and other areas.
Treatment should be given as soon as signs of fleas appear, and repeated regularly. Delays in treating the infestation may lead to flea-transmitted diseases.
Once-a-month topical products are the most commonly used products to kill parasite infestations. They are normally applied on the back of the pet, and their advantage is they also provide protection from further infestations. Sprays are available as aerosols and pump bottles, and they are meant to be applied on all parts of the pet. Dips and rinses are also available, but they are not as common as the other such products because they are the most dangerous for the health of the pet.
In 2009, the US Environment Protection Agency conducted an investigation into the reactions of many pets to topical flea products and released preliminary reports in the spring of 2010.
Also, different treatments are available for dogs from natural alternatives to chemical-based products that include topical medications and oral medications. Although common remedies provide natural options with natural ingredients such as lavender, pennyroyal, neem, and sweet mace, which are insect repellents, care should be used since "natural" does not always mean nontoxic.
Evaluations of the toxicity of flea treatment products have been scientifically studied and are available online from the Natural Resources Defense Council and a list of less-toxic and alternative treatments can be found in the reference book, Flea Control Secrets, which maintains a blog specifically on flea treatment.
Alternative treatments include homemade repellents. Garlic, brewer's yeast, and apple cider vinegar are effective in repelling fleas on healthy dogs. Sick or immunodeficient dogs tend to attract more fleas and may require both commercial and alternative treatment.
There are numerous natural flea control methods that can be tried before, or in conjunction with, chemical treatments. These include diatomaceous earth, essential oils, various shampoos, and herbs.
Toxascaris leonina is a common parasitic roundworm found in dogs, cats, foxes, and related host species. Toxascaris leonina, or T. leonina, is an ascarid nematode, a worldwide distributed helminth parasite which is in a division of eukaryotic parasites that, unlike external parasites such as lice and fleas, live inside their host. The definitive hosts of T. leonina include canids (dogs, foxes, etc.) and felines (cats), while the intermediate hosts are usually rodents, such as mice or rats. Infection occurs in the definitive host when the animal eats an infected rodent. While T. leonina can occur in either dogs or cats, it is far more frequent in cats.
The life cycle of T. leonina is fairly simple. Eggs are ingested and hatch in the small intestine. The juveniles then penetrate the mucosal lining of the small intestine. After growth and molt, they return to the intestinal lumen and mature. The adult female worm lays eggs which are passed in the feces of the dog. The eggs become infective after 3–6 days in the environment. Rodents are usually the intermediate hosts of T. leonina. The rodent ingests the eggs and, once the eggs are hatched, the larvae migrate through the tissues of the rodent. The definitive host is then infected with this parasite when it eats an infected rodent.
The egg of the T. leonina is usually more oval than round. The prepatent period for T. leonina is two to three months. The adult worms are usually 3-4 inches long and can be seen in the feces and vomit of the animal.
Toxascaris leonina differs from other Toxocara in that the larvae do not migrate through the lungs; but rather, the entire developmental cycle occurs in the gut.
Roundworms absorb the nutrients from the animal, which can interfere with digestion and can also damage the lining of the intestine. Animals may not show any outward symptoms of roundworms at all, or in other, usually more severe cases, animals may have diarrhea, vomiting, loss of appetite, experience thinning, dull coats, and in puppies or kittens, can develop distended abdomens, or "pot-belly" appearance.
Infection symptoms are similar to infection by other Toxacara species (T. canis, T. cati). It is a common cause of diarrhea in young animals and can cause vomiting as well. Sometimes the worms themselves are vomited up, which can be alarming as they can be quite large with females reaching lengths of up to seven inches. The worms consume the host's food and can lead to lethargy and a classical pot-bellied appearance. Extreme cases of severe infections can lead to pneumonia as the worms migrate, and if there are enough worms the intestine can become obstructed.
It is recommended to de-worm all puppies and kittens at 6 weeks and repeat treatment 2–4 weeks after the first treatment. T. leonina roundworm infections are treated with the same medication protocol as the T. canis or T. cati roundworm infections (see Toxocariasis). Therefore, when eggs are seen on a fecal flotation exam, or fecal swab, it is not necessary to determine which species is present. Roundworm infections are treated with medication, called "de-wormers", and includes such drugs as fenbendazole, pyrantel, milbemycin oxime, and piperazine.
To prevent reinfection of parasitic roundworms, it is recommended that anything that the animal has been in contact with should be cleaned thoroughly or replaced, including bedding and kennels. It is also strongly recommended that outside areas where defecation may occur be cleaned, as well as all feces removed daily from outdoor pet runs, crates, and the yard.
Humans are usually not infected with T. leonina; however, this parasite has been found in humans in a few instances and is a cause of visceral larva migrans in children, though less frequently implicated than is Toxocara canis, the most common roundworm parasite found in dogs.
helm, arth (acar)
helm, arth (lice), zoon
Chaetocnema hortensis also known as Corn Flea Beetle and Clover Flea Beetle, is a species of flea beetle from Chrysomelidae family, that can be found in Texas, USA and Canada.
The species are black coloured, with orange legs and antennae. Their size is quite small, about 1/16th of an inch.
The females lay eggs in a soil, which either have leaves or stems of plants growing nearby. The newborns hatch out of the eggs in 7 to 14 days, and turn into larvae. While in their larvae stage, they have small worm-like bodies that are white coloured. The larvae feeds especially on plants roots, causing a serious damage to the plant. Then it transforms into pupae, and a week later, into an adult.
The species are known for causing damage to crops. The damaged plants include sorghum, soybeans, sweet corn, small grains, and some vegetables. Not only does it feed on them, and destroying it, the species also transform a disease, known as Stewart's disease, to the crops. They do that, by removing the leaf tissue from the plant. Removal of a tissue, opens a wound to the plant, and the disease start spreading from plant to plant. They feed on both sides of a leaf (upper and lower parts), which includes epidermis and the veins. Aside for that disease they also transmit a specific version of it, called Erwinia stewartii, which is also known as Pantoea stewartii. This version of a disease is harmful for certain corn products. The beetle transforms this bacteria by accumulating and clogging the vascular system of the plant, while it feeds on it. Its hard to tell when the plants getting it. Some plants will get while in seeding stage, while the others will get it in a later stages. However, majority of corn is resistant to the disease. The disease is common among sweet corn then the field ones. Sweet corn plants can get infected on the early stages, and therefore are most affected. A young plant that gets the disease can become stunted, and starting to wilt. In the later phase of the infection, the plant can suffer some tassling. But it doesn't concern sweet corn, due to the fact that its being harvested before the symptoms will occur, which are visible in fall. The sign of symptoms doesn't appear until early summer, and that's the time when lots of leaf lesions start appearing on leaves. Some plants, however, may die before the tassling, due to the leaf beetle activity.
Oriental rat flea
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Health Medical Pharma