External signs of a water strider
Water striders are insects whose name very accurately matches their lifestyle. There are about 700 species of water striders and they all live in water, gliding along the surface of the water with extraordinary ease. With their elongated shape they resemble small boats.
Water striders (lat. Gerridae).
The protective coloration of water striders is brown, dark brown, sometimes almost black. This device allows the water strider to remain invisible to birds against the background of the dark color of the surface of standing reservoirs.
Typically, water striders that live in large bodies of water do not have wings; they simply do not need them.
And the inhabitants of small puddles desperately need wings to fly from place to place as the reservoirs dry up. These water striders have fairly well-developed membranous wings hidden under their elytra, but insects rarely fly.
Species and habitat
Water spiders are distributed throughout Europe, Asia Minor, Siberia and Kazakhstan. They can be found in the Caucasus, Sakhalin, the Far East, Tibet and Korea.
Hydrachna cruenta mull
Red arachnids belong to the genus of mites. Outwardly, they look like round balls that seem to roll along the surface of a reservoir. They live in warm, standing water in wetlands. They feed on small crustaceans and insect larvae.
Dolomedes fimbriatus
This spider, strictly speaking, cannot be classified as aquatic, since the arthropod lives above or near a body of water. To be able to catch prey, he builds unusual rafts, tying leaves and twigs floating on the surface of the reservoir with a web. Having reached the victim, he kills her, drags him onto his ship and eats him. If necessary, the spider dives, but unlike the silverfish, it dives shallowly and not for long.
Clubionafallax
In Russia, you can most often find dropsy (Clubionafallax), a type of silverweed. She lives in swamps, forest lakes, and river backwaters. Usually black or gray-green in color. Females are lighter.
Movement of water striders on water
Water striders are real virtuosos of gliding along the surface of the water. They are able to use their long legs to run through the water, like speed skaters on smooth ice.
Having encountered an obstacle - a strip of duckweed or other aquatic plants, the “skaters” make deft leaps and overcome the obstacle with strong leaps. The main participation in such maneuvers belongs to the two rear pairs of legs. The water strider's legs are covered with a fatty substance and are not wetted by water, so the insect easily glides along the surface of the water. In addition, during movement, tiny turbulences appear in the water before the next stroke of the limbs. These mini-whirlpools help the water strider move across the surface without any effort, whether in a calm pond or in a restless ocean.
Scientists have proven that water striders of all sizes use their limbs like oars, rowing and transferring momentum to the water mainly through dipole vortices created by their legs. To test this assumption, the researchers created an artificial insect that could move like a water strider. In English, a water strider is “water strider” or “walking on water.” The robot was called a “robostrider,” and the artificial water strider was able to move through the water like its natural counterpart.
When moving, the water strider spreads its legs wide, evenly distributing its body weight over a large area.
The long, narrow body of the water strider, with sharp and fast movements, perfectly cuts through the air.
The structural features of the legs are also associated with the movements of insects through water: the thin legs of the water strider at the junction with the body are extremely thick, there are strong muscles that are involved in strong movements.
A water strider cannot drown, even if it is deliberately lowered into the water.
The ventral side of the body is covered with white hairs with a waxy substance, so water does not wet the body and legs of the water strider.
The fact is that air bubbles are held between the smallest hairs. And since the weight of the insect is small, this air prevents the water strider from drowning.
Description of the insect
Larva
The insect, which is in the larval stage, differs from adults in its massive body and shorter limbs. The body has a light brown or greenish color.
The food consists of various insects living near the reservoir, their larvae and eggs. Despite its miniature size, the larva is a real predator.
After hatching from the eggs, the larvae develop for about a month, gradually increasing in size. There are five stages of development. At the last stage, molting occurs. After molting, the abdomen is gathered into folds, which straighten after eating.
Adults
The size of an adult insect is from 1 to 30 millimeters. The body is elongated, with a narrow abdomen. The color is brown or brown. The head is small with long antennae, equipped with a proboscis. The lower part of the body is covered with a waxy coating. There are small fibers on the limbs that prevent the insect from diving. Thanks to the correct geometry, lightness of the body and special equipment such as villi, the bug uses the surface tension of water for high-speed movement.
Water bugs not only glide through the water, but also easily jump over small obstacles using their back pair of limbs. The middle pair of legs is slightly longer. The bug uses them instead of a steering wheel, changing the direction of movement. The front pair is also universal. With its help, the bug develops speed and slows down, grabs prey and holds it.
Most insects have membranous transparent wings hidden under their hard elytra. If necessary, they can move between bodies of water. For example, migrating during dry summers or moving in search of prey. However, most spend their entire lives in one place. And some don't have wings at all.
Water strider feeding
Water striders are predators. They feed on insects and small animals that they find on the surface of the water. Having detected prey with the help of large spherical eyes, the predator rushes at it and grabs it with its front legs, the shape of which is similar to a hook. Then the water strider uses its sharp proboscis, piercing it into the body of the victim and sucking out the contents. In a calm state, the water strider tucks its proboscis under its chest. The water strider has rather long antennae, which are organs of smell and touch.
The water strider is a predatory insect.
Huntsman spiders (Dolomedes)
Large representatives of these spiders hunt for fish, tadpoles and aquatic invertebrates, while smaller ones mainly feed on insects.
Hunting spiders are animals that can walk on water and even swim on its surface, raising their front legs or standing on their “toes” to catch the wind, which will help them move in the right direction. When hunting, huntsman spiders' hind legs are usually on floating wood or vegetation, while their front legs rest lightly on the surface of the water. In this way, they detect surface waves, which allow hunting spiders to find potential prey. If the spider detects a fish underwater, it uses its hind legs to push off and dive after it. Huntsman spiders also dive underwater when disturbed, a good way to avoid predators such as birds. Some species of hunting spiders are able to stay underwater for up to half an hour! They can breathe underwater because the spider's lungs are located on the abdomen, which is covered with small hairs that capture air, forming a kind of diving bell.
Breeding water striders
Water striders lay their eggs on the leaves of aquatic plants in a single row, with the eggs glued together with a slimy substance. The clutch looks like a long jelly-like cord consisting of about 50 eggs. Some clutches are made without a mucous substance and form a chain of testicles simply lying along the edge of the leaf of an aquatic plant, in this case the testicles are located parallel to each other in one row. Smaller species of water striders simply embed their eggs into plant tissue.
Insects lay eggs throughout the summer. In a reservoir, along with adult water striders, there are also larvae at different stages of development, very similar to adults. They are distinguished by their small body size and a more swollen short abdomen.
What helps birds stay afloat?
We have seen swans and ducks swimming on the lakes many times. They stay afloat easily.
This is because their feathers are hollow and they fit very tightly together, creating a layer of air. Bird feathers also have a lubricant that protects them from getting wet. Their body produces fat. With the help of its beak, the bird constantly lubricates its plumage with fat, which repels water. Water cannot wet the feathers, which helps the bird retain heat and float on the water.
This can be easily verified by the following experiment: take two balls of thread and dip one of them in vegetable oil. Then we put them in glasses of water and see that the oiled ball of thread floats, and the second one drowns.
Waterfowl also “run” across the water when taking off. This is how they manage to develop greater speed. Quickly moving their paws and simultaneously working their wings, they accelerate until they gain enough speed to take off. Then they push off with all their might from the surface of the water and take off. It's like an airplane taking off.
Features of the life of water striders
Water striders are excellent runners on water, but they are absolutely not adapted for long-term movement on land. Therefore, water striders come to land only when it is time to settle down for the winter. They lumber awkwardly along the ground in search of a secluded place. Insects hibernate near water, under bark, in moss or in tree crevices.
The front legs of water striders are shorter than the other legs and are necessary for grabbing food, pushing away when moving, and also for fighting.
Water striders do not miss the opportunity to hold on to their prey. Without dividing the piece, several fighters cling with their forelimbs from a running start, and, unable to resist, fall and roll on the surface of the water. The prey goes to the most cunning and dexterous water strider, which takes the food to a secluded place and devours it while the others sort it out among themselves. With the help of the front legs, the insect regulates the speed of movement, and the other four legs are a support and serve as a rudder.
They can suck human blood.
Diet
Do not think that this is a peaceful insect; the water strider is a real predator. She boldly attacks any small creature that is unlucky enough to find itself on the surface of the water. Such impudence is completely justified, since other insects are not able to fight back, being in an element alien to them.
The hunting principle of water striders is very simple. As soon as the prey falls into the water, they swim up to it with lightning speed and cling to the body with hook-shaped front legs. Then the predator pierces the prey's shell using a sharp proboscis located on the head. Afterwards, the water strider can only suck the liquid from the body of the unfortunate creature.
Types of water striders
Many species of water striders are found in reservoirs, the following species are known: large water strider, armored water strider, velia, stick water strider, small water strider and more than seven hundred species.
- The water strider is big. The insect's body reaches 17 mm in length. It has a reddish body color and has wings.
- The pond water strider is only 1 cm long. It is dark brown in color, the legs are light, and there are black stripes on the thighs of the forelimbs. Males have a black abdomen, females have a red abdomen.
- The saltwater water strider is smaller than its freshwater relative, only about 5 mm. She runs at a speed of 3.5 km/h. Attacks jellyfish, physalia, eats fish eggs. Lives in the Pacific and Indian oceans. Insects stick to open water and can be found many kilometers from the land surface. They don't have wings.
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Harm to people
Due to its small size, the bites of the water strider bug, found in Russia, are harmless to people and large animals. Of course, water strider bugs do not ambush warm-blooded animals, but they can accidentally bite when swimming, as well as on the shore when they are prowling in search of eggs and larvae. Green stuff is enough to disinfect the bite site.
More aggressive varieties of this species are found in the tropics. They attack small fish and do not miss an opportunity to bite a person. In addition to the proboscis, these bugs also have a sting in their arsenal.
The pain after a bug bite is comparable to the pain after a bee sting. When a limb is bitten, it goes numb and the pain is felt for up to 1 hour.
. As a rule, this does not cause any consequences if there is no allergy to the substances injected by the bug. Then you need to take painkillers and antihistamines.
Of the variety of species of water striders, 4 species are found in Russia:
- big;
- armored;
- Velia;
- rod-shaped.
Bolshaya is the largest in Russia. The rod-shaped water strider is most often found in Siberia. Recognizable by its narrow body and slowness. Moves by alternately rearranging legs. Velia lives mainly in the northern regions. She has no wings, is not afraid of the cold and happily settles in icy springs.
(Basiliscus basiliscus)
Among the large animals that can walk on water is the helmeted lizard, or the common basilisk.
The green lizard has several other names, but its ability to run on water gives this species its most popular name: Jesus Christ lizard.
Abundant in the evergreen forests of Central America, green basilisks spend a lot of time in trees, but are never far from a body of water. When a lizard suspects a threat, it can jump from a tree into the water and run along the surface of the water for about 4.5 meters at a speed of about 1.5 meters per second. When the helmeted basilisk can no longer run on water, it resorts to excellent swimming skills.
6. Western American grebe (Aechmophorus occidentalis) and Clark's grebe (Aechmophorus clarkii)
The Western American grebe is commonly found in Canada and occasionally in Mexico. Clark's grebe lives in northern America. Both species of these waterfowl have a unique and wonderful mating ritual. While running through water, birds make 22 paw strikes per second. These grebes feed on a variety of fish, shellfish, crabs and salamanders. During nesting, the birds form monogamous pairs on inland lakes in western North America, and migrate to the Pacific coast in winter.
Brazilian dwarf gecko (Coleodactylus amazonicus)
Measuring only 2 to 4 cm in size, the Brazilian dwarf gecko is amazingly unsinkable! Although vulnerable to raindrops, this gecko has developed hydrophobic skin, allowing it to walk and even sit on water. The Brazilian dwarf gecko eats tiny invertebrates such as fleas and ticks. And he himself can become prey even for insects such as centipedes and spiders. These geckos live in the Amazonian rainforests of South America.
