Leg structure
The legs of insects are divided into segments - segments that are movably connected to each other. Each leg articulates with the body at the coxa, located on the lower surface of the body. From the coxal cavity, in order, there is the coxa, then the trochanter, femur, tibia and tarsus. The first two segments are “responsible” for the mobility of the leg relative to the body, the rest are for the movement of the insect along the surface. The junction of the thigh and lower leg - as in the body of higher animals - is called the knee, or knee joint. [3]
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Structure of insect legs
1 - Basin; 2 - Trochanter; 3 - Thigh; 4 - Shin; 5 - Foot
In most cases, each leg segment consists of one part, but sometimes the trochanter is divided into two segments. The shin may have spines and spurs, and, for example, ground beetles have a special narrow notch on it, with which they clean their antennae. [1]
The leg segments usually decrease in thickness from the base to the end, and the tarsus has a slight expansion due to the claws with which the insect clings to the base when moving along relief soil, tree bark, etc. In addition to claws, a suction cup helps insects stay on “difficult” surfaces.
The longest segment of the leg is usually the femur, followed, in descending order, by the tibia, then the tarsus, coxa and trochanter. This size ratio is most common, but it is not an absolute rule. There are many species whose limbs look completely different. [3]
All insects lead different lifestyles. Some must be able to climb smooth stems, some must swim in water, while others are predators and must have the appropriate “devices” for hunting. Depending on this, the structure of the legs can vary greatly. They are divided into specializations, or types.
Caterpillar legs
Thoracic and abdominal legs of the hawkmoth caterpillar: 1 - thoracic legs, 2 - abdominal legs.
Dragonfly and others
Another amazing representative of the insect world. This flyer uses her limbs in a special way. Her legs are equipped with stiff bristles. When a dragonfly flies, it arranges its limbs in such a way that it forms a kind of net. With this device she gets her food!
Small insects, caught in the interweaving of bristles, immediately become prey and are eaten by the dragonfly. The variety of ways and methods of using insect legs is truly enormous. They are not only designed for walking, like mammals. They are used to row, and cut, and grab. Insects also use their legs to clean their antennae. For this purpose, the limbs are equipped with special grooves. But some species of butterflies use their front legs exclusively for rubbing their eyes. These limbs are atrophied and equipped with special hairs.
Types of legs in larvae
The legs of larvae (caterpillars) are very different from the legs of adults. They lack division into segments and other anatomical features. The larvae have short, usually soft, numerous legs that end in a wide or narrow sucker. There are thoracic and abdominal legs, as, for example, in the hawkmoth caterpillar (photo) . [2]
Running legs
N – running legs
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Types of legs in adult insects
Runners
Such limbs can be found in those who are forced to quickly move after live prey. For example, the fragrant beauty (photo) has long, thin legs that allow it to be more agile. [4]
Digging legs
N – digging legs
Digging
They are found in insects that live in burrows or are pests of the root system of plants. A well-known example is the Common Mole cricket (photo) , the first pair of legs of which are transformed into short, thickened limbs, equipped with powerful muscles and ending in a rounded, flattened tarsus with jagged edges. Thanks to this, she manages to break up dense lumps of soil and dig passages in it. [4]
Swimming legs
N – swimming legs
Swimming
This type of legs is a relative rarity, because such modified limbs in the form of “oars” are necessary only for those few insects that live in water. For example, if you look at a water bug (photo) , you can see that they are distinguished by a flattened, streamlined shape without notches or thickenings. This helps to move much faster in water, but if the beetle accidentally lands on land (which is possible, at least, because all insects breathe atmospheric air), such limbs will even interfere with movement. [1]
Jumping legs
H – jumping legs
Jumping
The four-segmented hind legs of the large green grasshopper (photo) and other representatives of the Grasshoppers are distinguished by the large length of the thighs and tibias, as well as their special connection (“back knee”), which allows them to move distances tens of times greater than the size of their body. [1]
Grasping legs
N – grasping legs
Grasping
The front pair of grasping legs can be seen in a praying mantis (photo) , which, with their help, “sorts out relationships” with relatives or hunts small and medium-sized insects, not only pests, but also beneficial ones, for example, bees. [4]
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walking legs
N – walking legs
Walking
In structure, they are not particularly different from running segments, but usually have a shorter length and a smaller difference in size between adjacent segments. Walking legs are found in many Beetles, for example, weevils or leaf beetles (photo) . [4]
Collective legs
N – collective legs
Collective
On the lower leg and tarsus of the hind legs of a honey bee (photo) , there is a special device - a basket for collecting pollen. [4]
Water bugs
All aquatic insects are of interest from the point of view of the structure of their limbs. They demonstrate a completely different, but also unique adaptation. Science has asked how they can float on the surface of the water and not drown? It turned out that the water beetle has a kind of oar on its hind legs. Special hairs have grown on them, with which the insect makes rowing movements. This is how it floats on water. Some species are equipped with thickened and widened segments (this is the last section of the leg). Thanks to this structure, they can float perfectly on the water. Although these insects prefer to live in calm waters. It is difficult for them to fight against strong currents. The little creature does not have enough strength for this.
Insects
Insects belong to the largest class of animals, uniting a large number of groups. Their body, like that of all animals, is segmented, with articulated appendages. It is covered with a less or more hard exoskeleton, which contains the polysaccharide chitin.
- relatively small sizes;
- two pairs of wings (some are missing);
- three pairs of legs.
To date, 900,000 species of insects have been described, but there are many more of them - several million, some of them in a single copy. A number of shapes represent beautiful creations, such as butterflies.
Most insect species are terrestrial, but there are also those that lead an amphibious lifestyle. They are found in lakes and rivers, deep caves and deserts. Some species regularly make long flights, others spend their entire lives inside some fruit or even a seed.
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Cicada
The world of insects also has its own record holders. Thus, the structure of the limbs of the penny cicada allows it to jump to incredible heights, given its small size. If we draw an analogy with a person, we get two hundred and ten meters. It is clear that this insect has a pair of jumping limbs, very strong and fast. They act like a catapult, powerfully sending the body upward. In this case, the acceleration reaches four thousand meters per second. And in order not to slide off the plants on which the insect feeds, its front legs are equipped with sharp spines.
Number of legs in insects
So how many legs do insects have? One of the distinguishing characteristics of this class is the presence of three pairs of paws . They are all located in the thoracic region, with one pair on each of the three component segments.
Ancient insects also had legs on their abdomen, which is still reminiscent of the presence of rudimentary appendages in some modern species.
Under the influence of a certain lifestyle during the process of evolution, these creatures developed several types of paws. The most common of them are running and walking. Primitive insects have just such three pairs of legs. For some representatives of the superclass, changes in external conditions and subsequently in the manner of movement entailed modification of the limbs. The middle pair of legs did not undergo specialization during evolution. It is needed for walking.
Functions of the feet
The hind legs are equipped with spurs that perform various functions. Typically, ants often use them in battles with their brothers.
. Their paws have a special structure, which gives them special abilities. For example, for ants there are no obstacles in the form of a plane that are inaccessible. Small and nimble creatures can move along a smooth and vertical plane. The smaller the individual, the easier it is for it to move on any plane. Domestic creatures can easily run on a glass surface, but for example, cockroaches cannot do this.
And how many different maneuvers ants can perform on different surfaces thanks to tiny notches on their legs. The serrations help them grab onto almost any object. Various protrusions in the form of stones or bark serve as convenient stairs for them in natural conditions.
Thanks to their paws, some species of individuals can swim well.
. These include Australian bulldog ants. These insects are considered unique due to their rare qualities. They can swim across small puddles at a distance of 15 cm. Insects can also easily jump long distances up to half a meter in length. True, it is not their legs that help them in this, but their jaws, with which they push off the surface of the earth.
With their six legs, hard workers perform many jobs. They have the peculiarity of spreading their limbs wider than their body, due to which insects manage to carry objects several tens of times heavier than their own weight. This can be a load 50 times heavier than the weight of an ant.
The legs also serve as navigational material for ants. The insect remembers how many steps it took after a certain turn. On the way back, it makes an adjustment precisely to the given angle and the remembered number of steps.
There are weaver ants
which use their legs to build a nest. With the help of their paws, workers collect leaves and build nests from them. In this case, several dozen individuals can be taken. They grab the leaf with their jaws on one side and their paws on the other. The fastening material is the secretion secreted by the larvae. Thus, working individuals build housing for a large family; it is suspended, but very convenient for a whole colony of ants to live in. One can only imagine how many such nests the little hard workers managed to build.
What else do ants need paws for?
Ants need legs not only as a working tool, but also for movement. Individuals use their paws to transmit scent signals.
. On ant limbs there are glands that secrete pheromones with a strong aroma. While moving, insects leave marks using glands on various objects. Other individuals will immediately notice such a trail and will be able to easily detect it. A large number of ants, running along such paths, leave many traces, they become attractive to other ants.
Industrious ants are found everywhere and often live in our homes. When they move into a residential area, this becomes a real problem. Their appearance in the apartment is a mystery to most of us. They always move quickly, being constantly busy and busy. What is the structure of an insect, how many legs do ants have, and what role do they perform?
Ants belong to the family of insects, the order Hymenoptera, subfamily Antidae. This order includes their close relatives - bees and wasps
. In their structure they are all very similar, including the presence of wings. The only exceptions are certain types of ants. In total, there are 12,000 species of these insects on our planet.
The body of an adult is divided into three main sections:
- voluminous abdomen;
- large head;
- small breasts.
Insects are divided into 3 castes - females, males and workers.
. Females and males have differences in structure and they have wings. Working individuals do not have wings. The first ants, which still existed during the era of dinosaurs, had a primitive structure. Very often you hear the question, how many legs does an ant have and what is their speed? The answer is very simple - only 6 legs or three pairs of legs. They can be easily counted in adults; in adulthood, the limbs are clearly visible and distinguishable.
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Differences in appearance differ depending on the species as there are differences in the size and weight of the insect's body. For example, representatives of the tropics reach only 2 mm in length and weigh no more than 2 mg. There are also large species, the weight of which can reach 90 grams, and their body length reaches 3 cm. Despite the difference in weight and size, their structure is very similar.
How are limbs constructed?
The fact that insects belong to the class arthropods is confirmed by the structural features of the legs. They consist of several segments. The main segment is the coxa, which is attached to the corresponding segment of the chest and has a certain shape. Different types of insects have different shapes. In some, this segment looks like a transverse cylinder or ball, in others, the coxa looks like a wide leaf or cone. The mobility of the limb directly depends on the shape of the coxa.
The smallest segment, motionlessly articulated with the thigh, is called the trochanter. In some bugs it is double.
The thigh is connected to the lower leg by the knee, the leg ends with a paw with small claws. The paw consists of several (2-5) flaxes that are connected to each other.
Scientists, studying the number of limbs in insects of various classes, unexpectedly came across the fact that some of their representatives have an interesting mechanism in their structure - a gear. It can be represented schematically in the form of two interlocking wheels with notches. These wheels, through protrusions, interact and synchronize movement. This mechanism allows insects to jump at tremendous speed.
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Limb types
The most ancient are walking and running legs in insects. All other limbs took a long time to develop. It was a natural process associated with the need to adapt to the environment.
- Runners . They have an elongated shape and are slender. Consist of narrow or wide legs, lower leg, thigh and coxa. Examples of such legs are the legs of ground beetles and cockroaches;
- Walking legs . Designed for slow movement. Leaf beetles, longhorn beetles, and beetles that slowly crawl from leaf to leaf have such paws;
- Representatives of the order Orthoptera (grasshopper, locust, cricket) have jumping limbs Their last pair of legs is powerful and long. Many orthopterans jump eighty centimeters high; if they straighten their wings, they can cover up to 10 meters in one jump;
- The swimming legs (usually the hind legs, less often the middle ones) are covered with long hairs that form a wide rowing surface of a kind - an oar. Representatives with such limbs mainly live in bodies of water. They swim and dive well. These are, for example: swimming beetles, water lovers, smooth bugs;
- Digging - most often the first pair of legs. These limbs are powerful, short and flat.
- Collective limbs or basket limbs . Bees and bumblebees have it. The hind legs have special areas surrounded by chitinous, long hairs - baskets. Moving from flower to flower, the bees get dirty with pollen that sticks to the hairs. Using special brushes on its legs, the insect collects pollen in a basket, takes it to the hive and deposits it in the honeycomb.
- Suction limbs . In the males of some species (ground beetles, diving beetles), the legs at the ends of the tarsi have expanded segments. During reproduction, males use this device to clasp females when mating.
- Grasping legs armed with sharp spines. They are used by the predator (mantis) to hold its prey.
Insect limbs
Why do insects need legs? There seemed to be only one definite answer to this question: for movement, of course. In fact, the legs of insects perform several functions.
The function of an insect's limbs depends on the environment in which it lives, how it feeds and defends itself. Therefore, the paws of different species are adapted for digging passages, burying dead animals, making nests, protecting against attack, capturing food, jumping, swimming, and running.
How are the limbs of insects arranged?
The class insects belongs to the phylum arthropods. This name confirms the structural features of the legs of insects: they consist of several segments.
The main segment attached to the corresponding segment of the chest is called the coxa. The basin has a strictly defined shape. It differs among different types of insects. In some representatives the coxa looks like a ball or transverse cylinder, in others it looks like a cone or a wide leaf. The mobility of the limb depends on the shape of the coxa. The smallest segment is called the trochanter. Sometimes it is double. The trochanter is motionlessly articulated with the femur.
The longest component of the limb is the femur. It is longer than all parts of the leg and looks like a long cylindrical stick.
The next section is called the lower leg. It is comparable in size to the thigh, and together with it makes up the longest part of the insect’s limb.
The thigh and lower leg are connected using the knee. The leg ends with a paw. It consists of several flaxes movably connected to each other, their number is 2 - 5. The foot is armed with small claws. Usually there are two, and extremely rarely one.
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Even insects that fly or swim need legs.
Main distinguishing feature
Very often, many people who do not know biology well confuse ants with mites or spiders. In fact, the answer is simple - mites have 8 legs, and ants have 6 legs. Our arthropod fauna includes only spiders, ticks and ants. There are some beetles that can imitate the body shape of an ant in order to enter their nest. It is quite difficult to distinguish them from ants.
Laboring insects use their legs for more than just running. Due to the peculiarity of placing them wider than its body, as well as their strength, the insect lifts the weight above itself and carries it. The mass of the load can be 50 times the total mass of the ant itself.
The feet are also used to measure distance
. This is what ants living in deserts do. They serve as a navigational tool for them. The insect remembers how many steps it takes before turning and makes corrections, focusing on the angle.
Scientists have discovered an odor in the feet of ants that releases strong-smelling pheromones. These substances are used for marks during movement. Thanks to this, other individuals can follow the path, since it will become noticeable to them. A large number of marks will attract more brothers.
Sometimes mistakes happen in placing marks, after which the rest of the ants begin to go astray
and run in circles. They close their path with a fresher trail, which can later become a real disaster for the whole family.
Thanks to their thin but mobile legs, ants are able to work wonders, performing very difficult daily work.
Types of Insect Limbs
The most ancient are the running and walking legs of insects. The remaining types of limbs appeared in the process of long-term development, and, as a rule, are associated with various adaptations to environmental conditions.
The running legs have an elongated shape. They are slender, and the tarsus, lower leg, thigh and coxa are narrow or wide. This type of limbs is present in cockroaches and ground beetles.
Walking legs are designed for slow movement. These are the legs of beetles - longhorned beetles, leaf beetles, crawling from leaf to leaf, leisurely gnawing leaves.
Insects need limbs to move around.
- Swimming limbs
The hind legs of insects usually become swimming, and less often the middle legs. They are covered with long hairs that form a wide rowing surface - a kind of oar. Basically, representatives with such limbs live in bodies of water and swim and dive excellently. These are swimming beetles, smooth bugs, and water lovers.
Representatives of the order Orthoptera have jumping legs. These include locusts, grasshoppers, and crickets. Their last pair of legs is very long and powerful. Many representatives of Orthoptera jump in heights of up to eighty centimeters, and if they spread their wings at the same time, the distance covered in one jump reaches about ten meters.
Digging legs are characteristic of the mole cricket, dung beetle, and May beetle. Usually the first pair of legs become digging legs. The limbs of this type are powerful, flat and short.
The legs of grasshoppers give them the ability to move tens of meters in a matter of seconds.
- Collective limbs
The limbs of bees and bumblebees are called collective or basket limbs. On the hind legs of these insects there are special areas surrounded by long chitinous hairs; these are baskets. Bees move from flower to flower and get dirty in the pollen that sticks to the hairs of their bodies. With special brushes located on the legs, the bee collects flower pollen into baskets.
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the adhesive dust particles form a lump called “polnoka”. The bee carries pollen into the hive and deposits it in the honeycomb. Bee bread soaked in nectar is formed; it serves as a reserve protein food for the entire bee family.
Thanks to the collecting type of legs, the bee can “save” pollen.
- Grasping legs
Grasping legs of a praying mantis. They are armed with sharp spines, which the predator uses to hold its prey.
The legs of males of some species of insects - swimming beetles and ground beetles - have expanded segments at the ends of the legs. During the breeding season, males use these devices to grasp females during mating.
Grasping legs help not only to hold prey, but also to the female during mating.
