A small dark brown dot, instantly and almost imperceptibly to the eye, disappearing from the hand that caught it. Hated a tiny vampire, causing painful bites and not giving a quiet sleep to a pet. Finally, the carrier of the most dangerous diseases is all she, the flea.
It seems that nothing in it can not be interesting - a tiny parasite, just doing that biting and sucking blood. But why did the fleas become the objects of research of many scientists from all over the world? Why are they studied with such an interest in microscopes by amateur researchers and make amazing photos?
The reason is one: fleas are not as simple as they seem to an average person at their first meeting ...
It is interesting
One of the most famous researchers of fleas was the British banker Charles Rothschild, a multimillionaire who devoted all his free time to entomology. It was he who described the southern rat flea , the former cause of many epidemics of the plague, it was he who collected the most complete collection of these parasites, now stored in the British Museum. Ironically, Rothschild committed suicide because he suffered from encephalitis. And it is quite possible that he picked up this disease in one of his entomological expeditions.
A bit of biology
Flea - a parasite in many ways unique. As unique as it is demanding: fleas do not bite any animals, except warm-blooded birds and mammals. Only individual species are able to bite cold-blooded animals, but do so only in exceptional cases.
From mammals these insects prefer precisely those who tend to arrange nests and burrows. Such habits of the owners are necessary for parasites: insects do not live on their master constantly, but only jump on it in order to suck blood. And of course, parasitizing animals that are not tied to one place, they will be healthy to risk not finding a victim in the next bout of hunger.
Therefore, fleas prefer to settle in rodent burrows, bird nests, dog booths - here they are guaranteed they can count on a regular meal.
It is interesting
Among a huge number of species of fleas there are only a few dozen (up to 30) such that parasitize on nomadic animals - ungulates, hares, felines - and therefore are on their body constantly so as not to lose the source of food.
With a food source, fleas eat every day. But, if necessary, they can quite stretch out without food for several months. But after the expiration of such a post, the parasite pounces on the victim with special greed.
Thus, a person is a victim suitable for fleas. Especially the person who prefers to live in unsanitary conditions.
In this case, depending on the type of fleas can be fed in different ways. Some are sucked for the future, so that in the excrement they have undigested blood of the host. They suck from 20 minutes to an hour. Others eat often and gradually - mostly those species that live in the nests of rodents and birds.
Most types of fleas are not tied to a single master: they can easily eat on the skin of different animals and birds. Nevertheless, there are also such fleas, which feed only on the blood of one animal. Usually these are obligate parasites of bats.
Fleas are spread all over the globe. They are even in Antarctica, meeting in the nests of birds and at local scientific stations. The optimum temperature for their dwelling and reproduction is 18-27 ° C, but the fleas also withstand extreme temperatures, although they stop reproducing at the same time.
It is interesting
Bloch species Glaciopsyllus antarcticus - the most southern insect in the world. It was found on Queen Maud Land and near the Antarctic stations of Davis and Mawson - no other known insect is found here. This insect parasitizes on petrels and petrels, inhabited in the warm season in the nests of these birds, and in winter - wandering in their plumage over the oceanic expanses.
Appearance of fleas
Many people know how fleas look like, but not everyone has seen a parasite in such an increase, in which it is possible to look in detail at the details of the physique of this small parasite.
If you look at a photo of a flea made with a microscope, you can see that its body is very flattened from the sides and looks as if crushed. This is an evolutionary adaptation to easy movement among the hair or feathers of the host.
By the will of the evolutionary case, this same feature of the morphology of the insect helps it to be invulnerable when trying to comb, gnaw out, or simply crush the parasite with fingers. Indeed, a person can mechanically destroy a flea, only crushing it with a fingernail on a hard surface.
The photo below shows the same flea in front and side: the difference in the proportions of the body is clearly visible:
On a note
Interestingly, fossil fleas, whose age scientists date back 50 million years ago, look almost the same as modern ones. Apparently, for such a parasitic way of life, this form of the body proved to be optimal. For example, bugs and ticks also have a very flattened body, only in the other direction - from top to bottom.
Photo of the bed bug (body oblate in the horizontal plane):
A characteristic feature of fleas are elongated hind legs. It is thanks to them that parasites can jump beyond almost all other insects. When feeding the same or in a calm state, these paws bend so that they do not create any inconvenience to the insect in moving. With extended paws, the flea looks very original - the photograph below shows a canine flea under a microscope:
It is interesting
In relation to the range of the jump to the length of the body, fleas are among all insects in second place: more one-off jumps are performed by only one kind of cicada. With a body length of 2-3 mm, the flea jumps up to 19 cm in height and up to 30 cm in length - this is 100 times the length of its body. To man compete with a flea in the range of the jump, he needs to jump at least 160 meters in length.
Long jumps fleas provide not only strong hind legs, but also a special solid flap on the chest. When bending the insects of the hind legs, this shield is pulled back like a catapult lever. And at a push it is strongly thrown upwards, increasing range of a jump.
On a note
Not all fleas can jump. There are those whose hind tarsi have the usual length and which are constantly on the body of their host. And there is a view that for transportation between burrows of rodents uses as a transport ... earwigs.
All fleas are wingless. Given their lifestyle, the wings would be a hindrance to them moving in the owner's wool. Yes, and crush the winged insect in general easier than wingless. Evolution has decided that it is better for fleas to jump than fly.
Fleas do not have a piercing proboscis, which is found in other bloodsucking insects - mosquitoes and bedbugs. But they also completely manage their styloid-like jaws: the upper jaws cut through the skin of the victim, and the lower jaws expand the wound for the introduction of saliva into it.
True, the feeding parasite itself has to literally immerse in the wound its body to get to the blood vessel - in the photo it is good to consider what an insect looks like at this moment:
On a note
Unlike most blood-sucking parasites, fleas absolutely do not try to hide their bite and do not inject an anesthetic into the wound. At the same time, the enzyme contained in the saliva of the insect and prevents blood clotting causes terrible itching and the appearance of hemorrhagic edema at the site of the bite. At the same time, a portion of such an irritant, transmitted with one bite, is negligible-just 0.000004 cubic mm. Such "arrogance" of fleas is due precisely to their shape of the body: the person can practically not destroy an insect with his fingers, and therefore the parasite does not try to mask its bite.
The size of the flea's body had become a byword: the flea called everyone, when they wanted to emphasize its small size.
Indeed, the largest fleas, parasitizing on moose, barely reach a length of 10 mm. Usually fleas have a body length of 1-3 mm. Approximately the same length have also their larvae, but they look quite differently than adults.
Reproduction of fleas, appearance of their eggs and larvae
Fleas are insects with complete transformation. Their entire reproductive cycle looks like this:
- A well-fed female throws out a whole pack of eggs: a strong ejection of eggs ensures a wider dispersion of eggs. Several eggs are shown under the microscope - they are so small that it is very difficult to see them with the naked eye.
- A few days later, small white worm-shaped larvae emerge from the eggs, which burrow into the substrate on which the eggs lay. In most cases, this substrate is the litter in the host's nest. And they can be an old dirty carpet in the house. The larvae feed on either rotting organics or residual blood in the feces of adult fleas. As the larva grows several times molt, and after the third molt begins to surround itself with a thin silk cocoon, turning into a chrysalis.
- Pupa develops a few days, and from it comes quite adult and ready for parasitism flea. All that is left for her is to wait for the owner and continue her parents' business.
In a normal apartment, the flea larvae can quite successfully develop in the cracks of the floors, behind the skirting boards, in old carpets - in general, where there is at least a little rotting garbage.
The larva looks inconspicuous and at first glance looks like a simple little white worm. Only under a microscope in the photo can she discern a clearly glowing filled stomach:
One female for her life lays up to 450 eggs, 10-15 per serving. For one "shot" she needs at least once a good meal. But for work in the mode of the egg conveyor to the female, one copulation with the male is sufficient.
Photo of flea eggs:
Theoretically, a flea can live up to a year and a half, but under real conditions it hardly lasts up to 2 months - its life style is too dangerous, too many enemies.
Types of fleas and differences between them
There are many species of fleas. Scientists have more than 2000 of them, each of which specializes mainly in parasitism in one species of animals or birds. An inexperienced observer is unlikely to find a difference in how they look, and will not distinguish, for example, a rabbit flea from a suslivatory. Specialists distinguish them according to such signs, which are not very noticeable under the microscope.
For the person, the following types of fleas are most familiar:
- a human flea - indeed, there is one. It is she who is immortalized in the pictures of medieval artists, and it is about her that they say when they describe fleas in literature.
- Cat flea - the record for the number of human bites. It is small, very widespread and absolutely uncomfortable in choosing a host, eating well on both dogs, cats, and humans.
- Rat flea, the most dangerous, is an active carrier of the causative agent of the plague.
- A dog flea, relatively large and inactive, parasitic most often on dogs.
And this list can be continued for a very, very long time: the marmot, rabbit, moose, mouse - almost every kind of mammal has its flea parasite.
In the photo below you can get to know the representatives of the most common species.
Photo of human flea:
Photo of the cat flea:
Photo of the dog flea:
Fleas as carriers of dangerous diseases
If fleas were not carriers of the deadly diseases of man, people would not show such efforts in their destruction. But it was these insects, together with their immediate masters-rats, that were the cause of the devastating epidemics of bubonic plague in Europe. And even today, many populations of rodents - jerboa, ground squirrels, gerbils - are kept by epidemiologists under strict control, since the deadly pathogen continues to be incubated in the holes of these animals.
In addition to the causative agent of plague, other bacilli and viruses actively move on fleas:
- hepatitis A and B viruses
- brucellosis pathogen
- causative agent of typhus
- encephalitis virus
- eggs of various helminths.
A total of more than 200 dangerous diseases for humans can tolerate certain types of fleas. And that's why flea bites are terrible not only with itching and redness ...
In general, it is not difficult to distinguish a flea from any other bloodsucking parasite: such small sizes have neither mites nor bedbugs. And the ability to jump surely none of the six-legged vampires has. Flea is important only to look at the clothes and catch before it bites. And her identification is unlikely to be a serious problem.