What a tick looks like: a description of common species
Content:
Structural features
Ticks (Acari) belong to the class of arachnids, but because of their small size they are often ranked as insects. The body length of various individuals ranges from 0.2 to 5 mm. Scientists have found in the world more than 54 thousand species of representatives of the largest group of arachnids. Their body is whole or divided into two halves. The border is fuzzy, it is always shifted to the front. The main departments are called:
- The gnatosome is a compact front part of the body with the oral apparatus that forms the upper jaw - chelicerae and the hypostome - a plate of fused limbs of the pedipalp.
- Idiosome - an elongated body with walking limbs, can be whole or segmented.
The outer cover of the body is called a cuticle. It has a different structure: a leathery chitinous cover, a hard shield or a strong shell. Outside, the body is covered with bristles, which are the organs of touch. Ticks have 4 pairs of jointed legs. Due to the microscopic dimensions, without a special increase, they cannot be considered. The structure of the extremities is similar to insects, in arachnids there are 6 series-connected segments. They have bristles, claws and suction cups. The number of limbs changes throughout life. The larva appears with three pairs of legs.
Information. The legs of parasitic ticks are thick and short. They are covered with many strong suction cups that help to gain a foothold on the host.
A tick has 1 to 5 eyes, which have a simple structure. Species living in the soil do not have organs of vision. Breathing is carried out using special tubes - spiracles.
The structure of the oral apparatus
Mouth organs are located on the front end of the body. They are represented by the forelimbs - chelicera and pedipalps. Ticks have two types of oral devices:
- Stitching-sucking - this type is characterized by a deep change in the oral organs. The fused pedipalps turned into a hyposta and two stylet for piercing. Chelicerae form the proboscis, their outer surface is covered with teeth, contributing to reliable fixation on the body of the host. This type of oral apparatus is found in ticks that feed on plant sap and the blood of animals or people.
- Gnawing - a type peculiar to arthropods, preferring solid foods (seeds, flour, plant residues). They need to tear off pieces and grind pieces of food. The limbs of chelicera have become powerful claws designed to capture food.
Tick classification
Scientists divide the Acarina group into 3 independent squads:
- Haymakers are large land inhabitants of the tropics.
- Akarimorphic ticks are the most numerous group, numbering 30 thousand species. Among them there are pests of stocks and pathogens of human diseases. This unit includes: barn, subcutaneous, scabies, feather tick.
- Parasitomorphic ticks are arachnid order, consisting of 12 thousand species. Among them there are predators, parasites and saprotrophs (destroyers of the remains). The group includes the most dangerous pathogens in humans and animals: ixodic, gamazovye, argus ticks.
Attention.Parasitomorphic ticks have unique adaptive abilities; they have evolved for thousands of years with their hosts.
Food
The diet of arachnids is due to their lifestyle. Herbivorous families (spider mites, gall mites) suck juice from leaves, stems or roots. This leads to slow growth, drying and death of the crop. Agricultural pests are controlled with acaricidal drugs. Predators feed on eggs, insect larvae or representatives of their squad. The species Phytoseiidae is used by gardeners to control tick-borne phytophages.
Saprophages living in the soil eat rotting plant debris, bacteria, spores, algae. They contribute to soil processing and humus formation. Some species of acarimorphic ticks feed on food supplies. They settle in warehouses, mills, barns. They eat flour, cereals, grains, seeds, dried fruits and nuts. Parasites feed on blood, sebaceous secretions, hair or skin of the host. By the method of parasitism, they are divided into two types: subcutaneous and cutaneous.
Attention. Adults can fast for two years without harm.
Variety of species
Among the most common types:
Ixodidae
Representatives of the order parasitize on vertebrates (birds, mammals, reptiles). All of them are large in size - 3-30 mm, while feeding blood the body increases. They live in all climatic zones. The body is flat, oval in shape. They can parasitize on one, two or three hosts. In females, larvae and nymphs, the shield covers only a small part of the body. The rest of the surface is very elastic. In the process of nutrition, it is stretched, allowing you to increase the size of the idiosome several times. Males are arranged differently, the dorsal shield covers the entire body. They cannot eat for 6-10 days as females. Hungry individuals are yellow, brown, or black. After eating, they turn gray or pinkish.
Attention. The group includes carriers of the most dangerous diseases: tick-borne encephalitis, tularemia, typhoid, fever Ku, Lyme disease.
The duration of the life cycle depends on the seasonality of nutrition and reproduction. A fertilized female requires blood to develop eggs. Masonry is done in forest litter. Autumn larvae overwinter hungry, in favorable conditions they need 1-4 weeks for development. They feed on rodents. After molting, the larva turns into a nymph. In this state, she remains the entire warm season. In the absence of nutrition, the tick nymph hibernates in this state. Its transformation into imago is delayed until spring.
Bloodsucking activity occurs with the arrival of heat and humidity. The most dangerous for people is the periods from May to July. Hungry imagoes and nymphs lurk in the grass and bushes. They are able to feel a person in a few meters. To stick a tick is looking for a place with a thin skin. They prefer the armpit area, groin, neck, place behind the ear. Thanks to the introduction of an anesthetic substance into the wound, a person does not notice a skin puncture. Prevent bite special protective equipment for walking and the use of acaricidal repellents will help.
Argasum Mites
Representatives of this species parasitize on poultry and animals. The body of arachnids has a dense skin cover, their length is 3-30 mm. After saturation, the yellowish-brown color changes to purple. When a person bites a severe allergy to tick saliva. Surprisingly, adults of this species survive an eleven-year hunger strike.
Barn Ticks
This group includes microscopic pests of grain, cereals, plant root system, cheese. Arthropods do not exceed a size of 0.5-0.6 mm. Females lay eggs in products. After 4 days, hungry larvae emerge from them. After 5 days, she turns into a nymph. Pests are resistant to high and low temperatures. They quickly settle with infected products.Ingestion causes asthma.
Dust mite
Synanthropic organisms live in every human home. A body 0.1-0.3 mm long cannot be seen without special devices. The full cycle of their life is 60-70 days. Favorite habitat - bedding, pillows, mattresses. Feces of parasites contain enzymes that cause severe allergies.
Oribatids or shell mites
Oribatids are the most numerous group of arthropods that live in the soil. A characteristic feature of shell mites is a slow metabolism. They feed on plants, dead organics, mushrooms, and animal corpses. Their length is 0.7-0.9 mm, their habitat is forest litter, and the upper layers of the soil.
Gamasid ticks
This group has 6 thousand species, among them there are parasitic and free-living families. Their representatives have a body size of 0.2 to 5 mm, the color is yellow or light brown. Among the most dangerous species: rat and mouse mites. They are carriers of diseases. Tick bite causes tick-borne dermatitis. Chicken parasite harms poultry, causing disease and even death of livestock.
Demodex
A parasitic mite that lives in hair follicles. The length of his body is 0.3-0.4 mm. It feeds on skin cells with fat. The body of the parasite is covered with scales that help to gain a foothold on the host. It moves on the surface of the skin. Most often affects the elderly (2/3 cases).
Itchy itch
An intradermal parasite that causes scabies. The male pruritus is 0.23 mm in size and 0.45 mm in female. The parasite gnaws moves in the skin of the host. In them, it multiplies and feeds on blood. Most often affects the hands, armpits and groin.
Reproduction and development
Reproduction of ticks bisexual. The female is often larger than the males. Most species reproduce by laying eggs, but there are also viviparous.
Information. Depending on the type of ticks and natural conditions, a different amount of time is required for a change of generations. According to life expectancy, three groups are distinguished: generation develops over a year, offspring for growing up require from 2 to 4 years, 3-20 generations are replaced per year.
The tick development cycle includes 4 main stages:
- An egg is a large cell with a shell that has a round, flattened, or oval shape. It is sensitive to external conditions, can die in high humidity or a sharp cold snap.
- Larva - the egg shell serves as the first food for it. Usually the body of a larva is round in shape with three pairs of legs. To go to the next stage of tick development, they need food.
- Nymph - This phase is divided into three ages. Protonymph has a fourth pair of legs. At the age of deuterymphs, the limbs become covered with bristles. Trionymph receives genital tentacles.
- The adult is an adult, sexually mature individual, ready for procreation.
Information. The female is able to lay unfertilized eggs from which offspring emerges.
The species diversity of ticks is huge, they surround people in everyday life. Most of them are microscopic in size, so they are invisible to the naked eye.
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