This insect is carnivorous and belongs to the Coleoptera family. The swimming beetle quickly adapts to natural conditions, so it is not problematic to find it in the waters of Eurasia. In addition, it inhabits the waters of North America and is also found in Antarctic areas.
For its life activity, the beetle chooses bodies of water with stagnant water, which are rich in flora and fauna. The diet of the diving beetle includes objects of animal origin. He can even live in an aquarium if he is provided with all the necessary conditions and enough food.
Description and features
The diving beetle received a gift from nature with an elongated, streamlined body, which helps it move well in the water. On average, specimens grow to 45-50 mm. The color of individuals is most often nut-brown or black.
The body of a beetle is a fixed structure of three elements: the head, thorax and abdomen. The forelimbs, of which there are two pairs, help the beetle linger under water. It grabs onto plants with hooks with which these legs are “equipped.”
The hind limbs are adapted for swimming and are covered with hairs, and their design is similar to small oars. Even the swimming style itself is similar to how a boatman rows oars, the two hind limbs move simultaneously.
The insect also has well-developed wings, which it does not use often. The swimming beetle flies only when food runs out or its favorite water reservoir dries up. The eyes of the diving beetle are unusual. They are made up of nine thousand facets, small ordinary eyes.
This eye structure helps the insect to navigate very well under water and distinguish between stationary and moving objects. The organs for grasping food are very well developed - the jaws are sharp and powerful, which makes it possible to eat prey alive.
Swimmers spend most of their time underwater, but they must swim to the surface from time to time because they need fresh air to breathe. On the abdomen of the swimmer there are special-purpose holes through which oxygen enters and then goes through the trachea to all parts of the body.
In order to replenish the resources of necessary oxygen, the beetle swims to the surface and pushes its abdomen outward. The oxygen replenishment procedure should take place at least once every 15 minutes. Beetles use air not only for breathing; a special bag helps them control their descent and ascent.
And the swimmer breathes through its belly...
Swimming beetles breathe atmospheric air. They rise to the surface and expose the back of their abdomen from the water. Through the spiracles, which open on the back, oxygen flows through the tracheal tubes throughout the body. When the beetle dives, an air bubble will remain under its elytra, it will serve for breathing and as a hydrostatic apparatus. When the oxygen supply runs out, the beetle will float to the surface again. On average this happens every 8 minutes.
Kinds
About 600 species of different swimming beetles are known. The following species live in mid-latitudes:
1. Fringed swimmer . The most common and famous species, as well as the largest specimen. It is distinguished by the presence of an ocher-colored border, which decorates the entire body of the insect. A grown individual reaches 30-35 mm. Such beetles are common in Europe and America, Japan, Transcaucasia and the Sakha Republic.
2. Latissimus swimmer . The largest and rarest species of diving beetles. Adults grow up to 45 mm. They like to settle in bodies of water with clean water and high oxygen content, which is why the population is declining. Listed as an endangered species in the Red Books of several states.
3. Phalarope or striper. It is found in bodies of water with stagnant water, where there is a lot of its favorite food - tadpoles. It is smaller in size than the fringed diving beetle; an adult is 12-16 mm. It can be found wherever there is standing water, as well as small fish and tadpoles, which it grabs and devours with extraordinary speed.
When a life-threatening situation arises, the beetle releases a toxic milky liquid that covers its body. An unpleasant-smelling liquid scares away potential enemies, and they lose interest in it. Beetles are common in Russia, the northern territories of the African continent, the islands of the Sea of Japan and East Asian countries.
4. Diving . These beetles are quite compact in size, growing up to 0.5 cm, and this is their maximum length. Among this type of insect the most familiar are:
- The flat diving fish is a strong and well-fed individual, covered with long and densely growing hairs. The sides and front of the back have an uneven, rough surface;
- The swamp dive is smaller in size even than the flat dive. The maximum value is up to 3.5 mm. It can be identified by the presence of red-red spots located in the eye area. Despite the name, such an individual can be found in forest lakes and slow-flowing rivers. Inhabits vast territories from the Atlantic Ocean to Sakhalin.
5. Prudovik . Lives in wild ponds covered with vegetation. The color is dirty brown, the wings are covered with a pattern in the form of transverse notches.
Marriage "games"
Once in the water, the swimmers begin hunting, this time for the female. Having seen the lady, the gentleman will not waste time on courtship and other romance. He grabs it with his front paws and immediately gets down to business. In this case, the male is on top of the female and only he can expose his abdomen to the surface to replenish oxygen reserves. The female has to be content with the reserves under the elytra. And if only one suitor sets his sights on her, then everything will be fine, but if there are several males in a row, which happens at the beginning of the mating season, she will most likely die from suffocation.
Lifestyle and habitat
In nature, it is very rare to find living creatures that can both fly and stay under water for a long time. The swimming beetle lives only in places where there is fresh water and there is no strong current. These beetles fully confirm their name by their way of life. 90% of the time the predator is underwater, tracking prey or resting. Rest is most often combined with replenishing oxygen supplies.
You can see how the beetle lies on the surface with its abdomen up, so it fills its organs with air so that it can then stay under water for some time and return to hunting.
The water beetle swims magnificently, and it’s rare that you won’t see it in any pond. Thickets along the shores of forest lakes and small lakes in water meadows often collect huge numbers of insects. The fast current apparently creates noticeable interference when hunting small predators, and they also have problems when they need to take in air, which is why the habitat is stagnant water.
Although the wings of an insect are adapted for flight, in order to take off, it needs to get to land. The beetle moves on land rather awkwardly, walking in a waddle, swaying from foot to foot. Swimming beetles leave their favorite body of water only in the event of drought and other natural causes of shallowing of the water area.
An interesting feature: swimmers are also active at night. They continue to hunt even in the dark; at this time of day they fly from one body of water to another. Beetles do not see very well at night, which is why they often get into trouble, mistaking surfaces with glare for water surfaces. When diving on wet and shiny objects, swimmers often break.
Its small size and conspicuous appearance should make the diving beetle an accessible prey item for other predators, but it has a defensive weapon in its arsenal. When danger arises, the beetle's glands release a cloudy white liquid that has a disgusting, pungent odor and a sharp, unpleasant taste. This deters even larger predators and is a guarantee of safety.
Relations within the community are quite complex, if not cruel. When two individuals meet, they start a battle for territory, biting and beating each other. Swimming beetles survive the winter cold in cozy burrows, which they make for themselves as frost approaches. At this time of year they sleep.
Difficult period
During the winter, swimmers hibernate. Immediately after waking up, mating season begins. Having left the underground bedroom, the beetle rises into the air and flies in search of a suitable body of water. In flight, it relies on its vision, which sometimes fails, and the beetle flops onto wet asphalt or a metal roof. It can also fall a few centimeters or meters from the reservoir, and then the rest of the journey has to be done on foot. On land, the swimmer moves very clumsily, but quite quickly.
Nutrition
The swimming beetle in the photo looks like a harmless insect. But this is very far from reality, since the insect is a voracious predator. The greatest threat to all inhabitants of the reservoir is not even an adult, but a larva of the swimming beetle . This is one of the most merciless types of creatures that inhabit ponds.
The large crescent-shaped jaws are not used by the cub for chewing prey, but with their help the larva holds its trophy like pincers. Through them, a very toxic substance comes from the predator’s esophagus, which causes paralysis in the prey.
The next portion of the substance, which is ejected from the esophagus, decomposes the victim’s tissues to a jelly-like state, and the larva begins to absorb this substance. She has an immoderate appetite and resumes hunting as soon as she has dined. Interestingly, food for the larvae is only what moves; the larvae do not attack stationary objects.
Adult beetles are as insatiable as their larvae. Small fish, tadpoles, fry and other insects are not a complete list of what the diving beetle eats . A hungry beetle can attack frogs and fish, the size of which is close to 10 cm. Of course, one beetle cannot cope with it.
But the wounded fish attracts other swimmers with the smell of its blood, and then the attack occurs as a group. The beetles do not kill their trophy, but try to eat it alive, gnawing off piece by piece.
A large number of beetles can cause significant damage to fish populations in water bodies. Swimming beetles and fry live in the same aquatic environment, which sometimes leads to the complete disappearance of fish, since the fry are devoured by an insatiable animal.
Natural enemies
When in danger, these waterfowl insects release a white secretion with an unpleasant, pungent odor that scares away predators, so the swimmers have few natural enemies.
For the larvae, the greatest danger is represented by riders who lay eggs directly in the body of a small individual, which leads to its subsequent death.
Adult beetles are eaten by birds of prey, large fish, and small mammals. In fish farms, crucian carp are bred to kill these insects.
Reproduction and lifespan
The swimming beetle is an oviparous insect, like many Coleoptera. With the first warm days, when the water in reservoirs warms up, the beetles leave their wintering place and begin to look for water spaces in which mating could occur. Since the whole process takes place under water, it often ends tragically for the female.
Having chosen a suitable female, the male sits on her back, securing himself on the slippery surface. He is helped in this by two suction cups located on his front legs. Moreover, the female spends the entire mating process under water, and her partner, who is on top, is able to breathe. The tip of the abdomen, protruding above the surface of the water, helps him in this.
The resistance preceding crossing and the process itself continue for a longer time than the insect is accustomed to doing without breathing. For this reason, situations arise when the partner may not have enough air and die. This is most likely to happen when the female has to mate with several males in a row.
If the process goes without any unpleasant incidents, the female attaches the clutch to the stems of plants, piercing them with the ovipositor, and lays eggs there one after another. One such clutch can include up to one hundred eggs, the size of which reaches 5 mm. The development of the swimming beetle is not a quick process. The larvae will appear only after 2-5 weeks, depending on weather conditions and water temperature.
The swimmer can remain in the larval stage for up to 2 months, then it emerges from the water and begins to move on land to dig a hole for pupation. The adult beetle will emerge from the pupa in 20-35 days. He will spend about another week in his hole, waiting until his covers harden, and then he will go looking for water.
Insects live on average about one year in the wild. Those who like to place a beetle in a home aquarium can expect it to live there for 2-3 years.
Life cycle
After mating, the female diving beetle finds cracks in the stems of aquatic plants and lays eggs there. The eggs hatch into larvae that live and feed in the water, rapidly gaining weight. In mid-autumn, the larva crawls ashore, digs out a chamber in the soil and pupates there. At this time, the larva thickens, reducing the size of its body.
After a few weeks, the pupa turns into an adult, but the adult is in no hurry to emerge to the surface. The beetle continues to overwinter in the ground until spring. At the beginning of April, the first insects begin to crawl out and live only 4–5 months.
Swimming beetle larva
Swimming beetle larvae are very different from adults and are more like scorpions. They lead an aquatic way of life, constantly moving along the bottom of the reservoir in search of food. Since birth, they hunt small aquatic animals.
First, the larva attacks the victim, digging into it with its jaws, then injects gastric juice into it and waits until the animal’s insides are digested. After this, the larva simply sucks out the internal contents and goes in search of the next victim.
Interesting Facts
There is an opinion that the diving beetle chooses weak and sick inhabitants of the pond as victims for attack, that is, it is, in fact, an orderly. The diving beetle usually does not show hostility towards a person who finds himself in the same water pool. But the bite is very painful even for a person.
The sharp pain associated with the bite may go away after some time, but swelling occurs in the bitten area, completely disappearing after 14-20 days. The wounded area must be washed, treated with disinfectants, bandaged and a cold compress applied.
Most often, beetles show aggressiveness towards those who try to catch them and pick them up. At home, experts do not recommend keeping swimming beetles and ornamental fish in the same aquarium, as the predator will attack them and can seriously injure them.
What does a beetle eat?
Swimming beetles are predatory insects. They, like river inhabitants such as the otter or beaver, can pose a danger to entire populations of fish. Small fish, insects, frog tadpoles, mosquito larvae, aquatic worms, as well as dead toads are what the swimming beetle feeds on.
The rather sharp and wide mandibles of beetles are designed to destroy prey, the size of which may seem many times larger than their own. The swimmer is not afraid to attack even a large inhabitant of the reservoir. When attacked, the victim tries to throw off the predator with a sharp movement. But the wound inflicted by the beetle’s mouth begins to bleed, as a result of which the released droplets of blood become a signal for the attack of other swimming beetles.
If you keep the beetle at home, you can offer your pet fish or meat as food. It is not recommended to place the diving beetle in the same aquarium with ornamental fish; the possibility of an attack on them by a predator still cannot be ruled out.
What harm can insects cause?
It has already been said that aquatic beetles are capable of massively exterminating the population of other fish in special farms, thereby causing harm to their owners, thereby causing irreparable material damage. Most often they eat the fry of other fish.
To avoid this problem, it is recommended to take the following measures:
- the artificial reservoir must be completely drained and the bottom treated well using liming,
- install a fountain in a pond or other body of water that will increase the movement of water, as a result of which the swimmer will not be able to hunt normally and will choose other places to live,
- launch the crucian carp.
So, we looked at the characteristics of such an insect as the swimming beetle, found out what it feeds on and how it reproduces.
Laying eggs
Immediately after mating has occurred, the female begins to lay eggs. Their length is about 7 millimeters and their diameter is 1.2 mm. One female lays about 1000 eggs per season, a particularly fertile one lays up to 1500. This is possible only with sequential maturation, so the whole process drags on until the end of June. Eggs are laid in plant tissue. For protection, the female cuts them with the ovipositor, however, this does not always save future offspring from parasites. One of the most dangerous enemies for swimming beetles is the prestwichia rider. These parasites lay several dozen of them in each beetle egg. The ichneumon ichneumon larva feeds on the diving beetle's egg, pupating inside it. Young parasites emerging from the dolls mate and then leave the shell. Prestwichia and caraphractus are the only enemies of swimming beetles.
Undesirable neighborhood
Having settled in a decorative pond, a predatory beetle attacks decorative fish and other inhabitants. Owners of ponds are faced with a difficult problem: how to get rid of the swimming beetle in the pond? The least labor-intensive way is to have crucian carp, which actively destroy the larvae of the swimming beetle. Another option is to temporarily install a pump or fountain that creates movement of the water mass. The insect prefers stagnant bodies of water, so it will leave its shelter and go in search of a better habitat.
If the above methods do not work, then all that remains is to drain the water, clean and disinfect the bottom. This will destroy the adults and larvae of the beetle. After treatment, water is poured in and new inhabitants are released.
Danger to humans
You can encounter a predatory beetle while swimming in a lake or in your own pool. The insect shows aggression towards humans extremely rarely. The bite is painful, but does not pose a threat to health. The swimming beetle bites in the water if it feels threatened. The pain from the skin puncture remains for several minutes. After some time, the wound swells and a lump may form. The beetles are not poisonous, so there is no allergic reaction.
The victim must be given first aid:
- wash the wound;
- treat with an antiseptic (iodine, hydrogen peroxide);
- apply a bandage;
- apply ice to relieve swelling.
Apple from the apple tree
Surviving females lay fertilized eggs in the fleshy part of the plants. The eggs of diving beetles are among the largest: 7 mm in length and 1.2 mm in diameter. After 8-40 days, real monsters will hatch from them: with six pairs of legs on a segmented body and a flat head with long and powerful jaws. The only goal of the larva is to eat as much as possible.
The larva practically does not hunt; most often it sits on algae, with only the tip of its abdomen exposed to the surface for breathing. The baby is ready to attack anyone; she plunges her terrible jaws into the victim’s body, through which she injects a cocktail of digestive enzymes and paralytic poison. The victim is gradually digested, and the larva, without releasing its death grip, sucks out the nutritious “broth”.
During development, the larvae undergo two moults, at the last stage they reach a length of 6.5 cm.
Rules for aquarists
Tips for beginner aquarists:
- Watch the behavior and appearance of the fish. The color should be rich, the eyes should not be cloudy. If you have any suspicions, contact experienced aquarists, describing in detail the problem, the parameters of the aquarium and the features of keeping the fish.
- Keep in mind that even in a healthy aquarium, in addition to plants and fish, other small inhabitants appear (for example, ciliates or small insects).
- Maintain your aquarium on time. Incomplete care of the aquarium stimulates fish poisoning and decreased immunity.
- When introducing new fish, study information about them. They may be incompatible in terms of required water parameters or temperament.
- If the fish dies, immediately remove the corpse from the water. Determine the cause of death by external examination.
- If the fish shows signs of illness, place it in a separate container.
- Do not knock on the glass or interfere with the life of the inhabitants of your home aquarium unless necessary.
- When you start breeding fish, learn what you can’t do without for successful spawning, and how many males a female is placed with.
- To avoid damaging the walls of the aquarium, use a non-metallic scraper.
- If stones are collected from the street, test them for the presence of heavy metal ions with acetic or citric acid. Stones containing undesirable elements will react when they come into contact with acid. Boil the soil thoroughly to avoid introducing parasites into the aquarium. Driftwood collected from nature must also be thoroughly boiled.
- To prevent fish from jumping out of the aquarium, cover the container with a lid.
- Proper use of an aquarium siphon, connecting equipment or feeding fish is impossible without training and preparation, it will take a little patience before the aquarium hobby becomes productive.
Science points to fish's ability to sense and recognize faces. Aquatic pets have their own characteristics and range of sensations. Don’t be lazy to create comfort in the world of underwater inhabitants, because fish are sensitive and intelligent creatures.
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Body parts
The swimmer's body consists of three sections. These are the head, chest and abdomen. All sections are motionlessly articulated with each other. All this, combined with the oval shape of the body, makes the beetle an excellent swimmer. The swimmer's head is retracted into the chest, the pectoral segments are fused, smoothly turning into the abdomen.
The head contains mouthparts and sensory organs. The swimming beetle is an active predator. Due to the fact that the mouthparts are directed forward, the insect can grab prey when chasing. The upper lip has the appearance of a transverse plate. Behind it is a pair of remarkably developed jaws that grab and crush the prey. Their ends are pushed forward, like pointed teeth. Behind the upper jaws there is a pair of lower jaws with palps; they are limited on the sides by the oral opening. Below the mouth is the lower lip. Short palps on the jaw and lip are organs of taste and touch.
With the help of their mouthparts, swimmers and some other insects capture, chew and crush prey. That's why they are called gnawing ones.
There are compound eyes on the sides of the head. Each one consists of 9 thousand simple eyes. The fringed swimming beetle, whose body shape is comparable in streamlining and strength to that of a submarine, distinguishes the outlines and size of moving objects. In front of the eyes, the insect has a pair of antennae, which belong to the organs of touch, smell and taste.
The legs and wings are located on the chest segments. Only the first segment can be seen on the back of the beetle. Its upper part - the so-called dorsal shield - is similar in shape to a trapezoid. The remaining segments of the thorax, as well as the abdomen, are covered with hard elytra (modified fore wings), which are protected from above by delicate hind wings. The remaining parts of the swimming beetle's body are hidden behind durable covers.
Stiff fore wings are characteristic of all beetles, which is why they are called Coleoptera. First, the swimmer raises its elytra, moving it slightly to the sides, then spreads its folded wings and only after that takes off. In flight, elytra and wings are as important for an insect as the supporting planes and propeller are for an airplane. On land, the swimming beetle moves rather slowly, while waddling from side to side, pushing off with its hind legs and moving its front legs.
