Sycamore is an evergreen plant. Sycamore tree: description and application. Contraindications and side effects

Starfish are animals with an unusual body shape, thanks to which they attracted the attention of people even in ancient times. Starfish belong to the Echinoderm type, in which they are separated into a separate class, numbering almost 1600 species. The closest relatives of these invertebrates are ophiuras, or snake-tails, very similar to them, and more distant holothurians and sea urchins.

The main distinguishing feature of starfish is, of course, their body shape. In general, the body of sea stars can be divided into a central part - a disk, and lateral outgrowths, which are usually called rays or arms. These animals are characterized by radial symmetry, so their body is divided into symmetrical sectors, the number of which is usually five. However, among sea stars there are organisms with a large number of axes of symmetry: in some species, their number can reach 6-12 and even 45-50.

Nine-armed starfish (Solaster endeca).

Each sector, respectively, includes a part of the central disc and an arm. It would seem that such a structure of the same type should result in the monotony of these living organisms. But it is precisely the shape of the body of sea stars that is very changeable. First, the relative length and thickness of the rays varies greatly: in some species they are elongated and thin, in others they have a triangular shape, sharply tapering towards the end, in others the rays are so short that they practically do not protrude beyond the edges of the central disc. Stars of the latter type have a very high central disc, and therefore resemble pillows. Thus, in most species of starfish, the length of the rays is 3-5 times greater than the diameter of the central disk, in the longest-armed by 20-30 times, and in cushion-shaped ones it tends to zero.

This bright ottoman on the seabed is actually the starfish of the New Guinea cult (Culcita novaeguineae).

Secondly, starfish differ in surface texture and color. Here the variety simply defies description - smooth, spiny, prickly, rough, velvety, mosaic; monochrome and patterned, bright and faded. The color range of these animals includes almost all colors, but most often there are various shades of red, less often blue, brown, pink, purple, yellow, black. Pale starfish tend to live in deep waters, while shallow-water species are vibrant.

This is the same New Guinean cult, but in a different color.

At first glance, starfish seem primitive, because they do not have any noticeable sense organs, a brain, internal organs are poorly differentiated, but this simplicity is deceiving.

The linchia starfish (Linckia laevigata) is bright blue in color, its rays are similar to sausages.

First of all, it should be noted that sea stars have an internal skeleton. They do not have a spine and separate bones, but there are many calcareous plates connected to each other in an openwork system.

Openwork plexus of skeletal elements on the surface of a starfish.

In a young starfish, skeletal elements are hidden under the skin, but over time, the skin over some of the calcareous spines wears off and they become visible from the outside. It is these thorns that give the starfish their spiny appearance.

The thorns on the surface of the starfish are covered with skin, but some of them are already exposed and have a shiny surface.

In addition, on the upper side of the body, in many species, calcareous plates can be seen, fused together or forming a network.

A whimsical pattern formed by skin and skeletal elements of a starfish.

Finally, the third element that influences the appearance of the starfish is pedicellaria. Pedicellaria are modified needles that look like tiny forceps. They play an important role in the life of a starfish, with their help it cleans the upper side of the body of debris and sand. All skeletal elements are interconnected by muscles, therefore, after the death of the starfish, its skeleton crumbles into calcareous plates and there is no trace of the animal.

The acanthaster starfish, or crown of thorns (Acanthaster ellisii), has thorny and poisonous thorns.

The muscular system in starfish is relatively poorly developed. In each ray there is a muscle cord that can bend the ray upward; this, in fact, is the limitation of the muscle movements of the stars. But mobility is not limited at all. Starfish can crawl, dig, bend, swim, but they do not do it with the help of muscles.

The scallop starfish (Patiria pectinifera) climb the algae.

These animals have a special body system - ambulacral. Essentially, this system consists of channels and cavities connected together and filled with fluid. A starfish can pump this fluid from one part of the system to another, causing its body parts to bend and move. The central part of this system is the ambulacral legs - tiny blind outgrowths of the ambulacral canals on the underside of the starfish. Each leg moves independently of the others, but their actions are always coordinated. With the help of these microscopic elements, the starfish is able to work miracles. For example, it is able to climb a vertical surface, it can stick to the glass of the aquarium for a long time, it can rears up, bulging like an angry cat, or maybe, grasping with two rays, push the shells of the mollusk shell apart. And all this is done by an animal practically devoid of a brain and eyes!

Translucent ambulacral legs are visible on the underside of the beam.

In fairness, it should be noted that sea stars still have some sense organs. These are the eyes located at the ends of each ray. The eyes are very primitive and distinguish only light and darkness; starfish cannot see objects. Starfish are capable of picking up chemicals (analogous to scent), only they sense them differently. Some species are very sensitive and can crawl to the bait for a smell for several days in a row, others can crawl past the victim a couple of centimeters and not smell it. The sense of touch is very developed in sea stars, they try to get rid of the sand that falls asleep on them from above, and also always strive to feel their way with the help of small tentacles at the end of each ray. The sense of touch tells the starfish who it encountered - a prey or a predator. The brain of a starfish is replaced by a group of loosely connected cells. Surprisingly, despite such a primitive structure of the nervous system, starfish can develop elementary conditioned reflexes. For example, starfish, which were often caught with nets, began to get out of them faster than those that were caught for the first time.

At the end of the ray of the starfish Asterodiscus truncatus, a decorated peephole is visible. The beam itself is covered with embossed limestone plates.

Another "strong", in the literal and figurative sense of the word, the system of sea stars is the digestive system. The mouth in these animals is located in the center of the disc on the underside, and the tiny anal opening on the dorsal side of the body. By the way, sea stars rarely use it (in some species it generally grows overgrown), preferring to remove food debris through the mouth. The stomach of starfish has outgrowths that extend into the rays, in these outgrowths stores of nutrients are deposited in case of hunger. And starfish starve regularly, as they stop feeding during breeding. The stomach in many species can turn outward through the mouth opening, and it stretches like rubber, taking any shape. Thanks to the expandable stomach, the starfish can digest prey that is larger than it. There is a known case when the starfish Luidia swallowed such a large sea urchin that it died, unable to spit out its remains.

In the middle of the central disc of the monilis phromia, a tiny anal opening is visible.

Other body systems are poorly developed in starfish. They breathe through special outgrowths of the skin on the upper side of the body, washed by sea currents. They have no gills and lungs, so starfish are sensitive to a lack of oxygen. They also do not tolerate water desalination, therefore they are found only in the seas and oceans. The sizes of starfish range from 1-1.5 cm for the miniature spherical podosphere star to 80-90 cm for the freyella starfish.

The name of this starfish speaks for itself - elegant fromia (Fromia elegans).

Starfish are globally distributed. They are found everywhere in all seas and oceans from the tropics to the poles. Of course, the species diversity is higher in warm waters than in cold ones. Most species prefer to live in shallow waters, some even find themselves on the shore at low tide. But among these animals there are deep-sea species, including those that live at depths of over 9 km!

Starfish in shallow water.

Starfish crawl along the bottom most of the time, they do it very slowly, the usual speed of an average starfish is 10 cm per minute, but a starfish can "hurry" at a speed of 25-30 cm per minute. If necessary, starfish can climb rocks, corals, algae. If a starfish falls on its back, then it is immediately turned over with its ventral side down. To do this, the animal bends two rays so that the ambulacral legs touch the ground from the lower side, and then the starfish turns the body inside out and takes the usual position. Some species can even swim awkwardly over short distances. Sea stars can be called sedentary animals; tagging of animals showed that they do not move more than 500 m from the place of initial catch.

The coriaster starfish (Coriaster granulatus) looks like a bun.

Despite the outward primitiveness and seeming helplessness, starfish are formidable predators. They are quite voracious and never refuse prey, except for the period of gestation. Only deep-sea species feed on silt, from which they extract food particles; cult sea stars, which prefer to eat fouling on corals, can also be called “non-predatory”. All other species actively hunt other animals.

A completely non-romantic relationship began between the starfish Solaster dawsoni and Hippasteria spinosa.

Most sea stars are not fussy, they eat everything that they are able to hold with their hands and what their "rubber" stomach will reach, without disdaining and carrion. Some species can only eat a certain type of food: sponges, corals, gastropods.

The Pentagonaster pulchellus starfish is also called a biscuit starfish for its cookie-like body shape.

Favorite prey of sea stars are the same as they themselves are inactive animals - sea urchins and bivalve molluscs. The star overtakes the sea urchin by crawling and eats it with its mouth. Bivalve molluscs have shells, the valves of which they close tightly in case of danger, so starfish treat them differently. First, the starfish sticks with two rays to the shell valves, and then begins to move them apart. It must be said that the ambulacral legs adhere firmly to the substrate thanks to the adhesive lubricant, and one single ambulacral leg can develop a force of up to 30 g! And on each ray of the starfish there are hundreds of them, so the star, like a real strongman, pushes the shells with an effort of several kilograms. However, the starfish does not need to push the shells apart to the full width; for a hearty dinner, a gap of 0.1 mm is enough for it! In this truly microscopic gap, the starfish twists its stomach (it can stretch up to 10 cm) and digests the shellfish in its own home.

The starfish asteria (Asterias rubens) pulls its hand towards the mollusk.

Most starfish are dioecious, and very few species have both male and female sex glands. The sex glands are located in pairs at the base of each ray. In the starfish asterins, young individuals are first male, and then change it to female. A special exception is the ophidiaster starfish, which has no males at all. Females of this species lay eggs without fertilization, this reproduction is called parthenogenesis. During mating, males and females combine their rays and sweep sperm and eggs into the water. The number of eggs depends on the type of development of the larva and ranges from 200 in those species that bear offspring, and up to 2-200 million in species with free-swimming larvae.

Mating starfish.

There are three types of starfish larvae. In some species, a free-swimming larva hatches from the egg, which feeds on microscopic algae, and then attaches to the bottom and gradually turns into a small star. In others, the free-swimming larva has large reserves of yolk, so it does not feed and immediately turns into an adult form. In starfish living in cold waters, the larvae do not separate from the mother's body at all, but accumulate near her mouth or even in special stomach pockets. During this period, a caring female relies only on the tips of the rays, and the body bends with a dome, under which the larvae are located. Since the larvae are located near the mouth opening, the female does not feed during this period. The larval form is the most mobile in the life cycle of sea stars; it is during this period that the larvae can be carried by currents over very long distances.

The starfish larva has bilateral symmetry.

In addition to sexual reproduction, starfish can also reproduce asexually. Most often this occurs in multi-ray species, the body of the animal is divided into two halves, each of which increases the missing rays. In other species, asexual reproduction can be the result of regeneration in the event of traumatic injury to the body. If a starfish is artificially divided into several parts, then a new organism will be formed from each. Even one ray is enough for recovery, but a piece of the central disk is absolutely necessary. Starfish grow slowly, so they look one-sided for many months.

The seagull has caught a starfish.

But the starfish Astropecten is friends with polychaete worms. On one star, up to five roommates can be found, who prefer to stay on the lower side of the body closer to the mouth of the star. The worms pick up the remains of the star's prey and even ... stick their head into its stomach. Ctenophores of a special species live on the starfish echinaster, which clean the surface of the star from fouling.

These bright spots on the starfish are Echinaster luzonicus - ctenophores (Coeloplana astericola).

Since ancient times, people have paid attention to the colorful animals of shallow water, but starfish were not of any economic interest to them. Only in China, sea stars are sometimes eaten, while attempts to feed sea stars to pets can lead to the death of the latter. This is probably due to toxins that some species accumulate by eating corals and poisonous shellfish. But with the development of the marine economy, people began to rank sea stars as their enemies. It has been found that starfish often eat bait in bottom crab traps and also raid oyster and scallop plantations. In a few years (this is how long it takes to grow oysters), starfish can destroy an entire oyster jar. At one time, they tried to destroy the sea stars, chopping them into pieces, but this only increased their number, because a new starfish grew from each stump. Then they learned to extract sea stars with special trawls, and kill with boiling water.

A very spectacular mosaic starfish (Iconaster longimanus).

The most malicious pest was the acantaster starfish, or the crown of thorns. This very large starfish feeds exclusively on corals, after which the crown of thorns leaves only a white lifeless path on the coral reef. At one time, these stars multiplied so much that they literally destroyed a huge section of the Great Barrier Reef off the coast of Australia. The unique geological formation was under threat of destruction. The fight against the crown of thorns was complicated by the fact that its thorns are poisonous to humans, the prick of the crown of thorns causes burning pain, although it is not fatal. Specially trained divers collected acantasters with sharp peaks in bags or injected a lethal dose of formalin into the body of a starfish. Only in this way was it possible to pacify the invasion of voracious predators and save the reef. Nowadays, all types of starfish are in good condition and do not need protection.

The crown of thorns eats up the coral.

Elegant fromia starfish (Fromia monilis).

Nine-armed starfish (Solaster endeca).

This bright ottoman on the seabed is actually the starfish of the New Guinea cult (Culcita novaeguineae).

This is the same New Guinean cult, but in a different color.

At first glance, starfish seem primitive, because they do not have any noticeable sense organs, a brain, internal organs are poorly differentiated, but this simplicity is deceiving.

The linchia starfish (Linckia laevigata) is bright blue in color, its rays are similar to sausages.

Openwork plexus of skeletal elements on the surface of a starfish.

The thorns on the surface of the starfish are covered with skin, but some of them are already exposed and have a shiny surface.

In addition, on the upper side of the body, in many species, calcareous plates can be seen, fused together or forming a network.

A whimsical pattern formed by skin and skeletal elements of a starfish.

The acanthaster starfish, or crown of thorns (Acanthaster ellisii), has thorny and poisonous thorns.

The scallop starfish (Patiria pectinifera) climb the algae.

Translucent ambulacral legs are visible on the underside of the beam.

In fairness, it should be noted that sea stars still have some sense organs. These are the eyes located at the ends of each ray. The eyes are very primitive and distinguish only light and darkness; starfish cannot see objects. Starfish are capable of picking up chemicals (analogous to scent), only they sense them differently. Some species are very sensitive and can crawl to the bait for several days in a row, while others can crawl past the victim a couple of centimeters and not smell it. The sense of touch is very developed in sea stars, they try to get rid of the sand that falls asleep on them from above, and also always strive to feel their way with the help of small tentacles at the end of each ray. The sense of touch tells the starfish who it encountered - a prey or a predator. The brain of a starfish is replaced by a group of loosely connected cells. Surprisingly, despite such a primitive structure of the nervous system, starfish can develop elementary conditioned reflexes. For example, individuals who were often caught with nets began to get out of them faster than those who were caught for the first time.

At the end of the ray of the starfish Asterodiscus truncatus, a decorated peephole is visible. The beam itself is covered with embossed limestone plates.

Another strong, literally and figuratively, system in sea stars is the digestive system. The mouth in these animals is located in the center of the disc on the lower side of the body, and the tiny anus is on the back. By the way, sea stars rarely use it (in some species it generally grows overgrown), preferring to remove undigested food debris through the mouth. The stomach of these invertebrates has outgrowths that extend into the rays, in them reserves of nutrients are deposited in case of hunger. And starfish starve regularly, as they stop feeding during breeding. The stomach in many species can turn outward through the mouth opening, and it stretches like rubber, taking any shape. Thanks to the expandable stomach, the starfish can digest prey that is larger than it. There is a known case when the starfish Luidia swallowed such a large sea urchin that it died, unable to spit out its remains.

In the middle of the central disc of the monilis phromia, a tiny anal opening is visible.

Other body systems are poorly developed in starfish. They breathe through special outgrowths of the skin on the upper side of the body, washed by sea currents. They have no gills and lungs, so starfish are sensitive to a lack of oxygen. They also do not tolerate water desalination, therefore they are found only in the seas and oceans. The sizes of these animals range from 1-1.5 cm for the miniature spherical podosphere star to 80-90 cm for the freelle starfish.

The name of this starfish speaks for itself - elegant fromia (Fromia elegans).

Starfish in shallow water.

Starfish crawl along the bottom most of the time. They do this very slowly, the usual speed of a medium-sized individual is 10 cm per minute, but the starfish can "hurry" at a speed of 25-30 cm per minute. If necessary, these animals climb stones, corals, algae. If a starfish falls on its back, then it is immediately turned over with its ventral side down. To do this, the animal bends two rays so that the ambulacral legs touch the ground from the lower side, and then the starfish turns the body inside out and assumes its usual position. Some species can even swim awkwardly over short distances. Sea stars can be called sedentary animals, their tagging has shown that they do not move more than 500 m from the place of initial catch.

The coriaster starfish (Coriaster granulatus) looks like a bun.

It was not at all a romantic relationship that tied this couple: the starfish (Solaster dawsoni) eats the prickly hippasteria (Hippasteria spinosa).

The Pentagonaster pulchellus starfish is also called a biscuit starfish for its cookie-like body shape.

Favorite prey of sea stars are the same as they themselves are inactive animals - sea urchins and bivalve molluscs. The star overtakes the sea urchin by crawling and eats it with its mouth. Bivalve molluscs have shells, the valves of which close tightly in case of danger, so starfish treat them differently. First, the starfish sticks with two rays to the shell valves, and then begins to move them apart. It must be said that the ambulacral legs adhere firmly to the substrate thanks to the adhesive lubricant, and one single ambulacral leg can develop a force of up to 30 g! And on each ray of the starfish there are hundreds of them, so she, like a real strongman, pushes the shells with an effort of several kilograms. However, the starfish does not need to push the shells apart to the full width; for a hearty dinner, a gap of 0.1 mm is enough for it! In this truly microscopic gap, the starfish twists its stomach (it can stretch up to 10 cm) and digests the shellfish in its own home.

The starfish asteria (Asterias rubens) pulls its hand towards the mollusk.

Most starfish are dioecious, and very few species have both male and female sex glands. The sex glands are located in pairs at the base of each ray. In the starfish asterins, young individuals are first male, and then change it to female. A special exception is the ophidiaster starfish, which has no males at all! Females of this species lay eggs without fertilization, this reproduction is called parthenogenesis. During mating, males and females combine their rays and sweep sperm and eggs into the water. The number of eggs depends on the type of development of the larva and ranges from 200 in those species that bear offspring, and up to 200 million in species with free-swimming larvae.

Mating starfish.

There are three types of starfish larvae. In some species, a free-swimming larva hatches from the egg, which feeds on microscopic algae, and then attaches to the bottom and gradually turns into a small star. In others, the free-swimming larva has large reserves of yolk, so it does not feed and immediately turns into an adult form. In starfish living in cold waters, the larvae do not separate from the mother's body at all, but accumulate near her mouth or even in special stomach pockets. During this period, a caring female relies only on the tips of the rays, and bends the body with a dome, under which the offspring is located. Since the larvae are located near the mouth opening, the female does not feed during this period. The larval form is the most mobile in the life cycle of sea stars; it is during this period that young animals can be carried by currents over very long distances.

The starfish larva has bilateral symmetry.

A new individual is formed from the cut off ray of the starfish. This shape is often referred to as a comet.

In the natural environment, sea stars have very few enemies, since sharp thorns, which can be poisonous, scare off large predators. In addition, these invertebrates, on occasion, try to bury themselves in the sand so as not to attract attention. Most often, sea stars get on the teeth of sea otters and seagulls.

The seagull has caught a starfish.

But the starfish Astropecten is friends with polychaete worms. On one individual, up to five roommates can be found, who prefer to stay on the lower side of the body closer to the mouth of the star. The worms pick up the remains of her prey and even stick their head into her stomach! Ctenophores of a special species live on the starfish echinaster, which clean the surface of the star from fouling.

These bright spots on the starfish are Echinaster luzonicus - ctenophores (Coeloplana astericola).

Since ancient times, people have paid attention to the colorful animals of shallow water, but starfish were not of any economic interest to them. Only in China are they sometimes used for food, at the same time, attempts to feed sea stars to pets can lead to the death of the latter. This is probably due to toxins that some species accumulate by eating corals and poisonous shellfish. But with the development of the marine economy, people began to rank these animals as their enemies. It has been found that starfish often eat bait in bottom crab traps and also raid oyster and scallop plantations. In a few years (this is how long it takes to grow oysters), starfish can destroy an entire oyster jar. At one time, they tried to destroy the predators, chopping them into pieces, but this only increased their number, because a new starfish grew from each stump. Then they learned to extract sea stars with special trawls, and kill with boiling water.

A very spectacular mosaic starfish (Iconaster longimanus).

The most malicious pest was the acantaster starfish, or the crown of thorns. This very large echinoderm feeds exclusively on corals, after which the crown of thorns leaves only a white lifeless path on the coral reef. At one time, these stars multiplied so much that they literally ate a huge section of the Great Barrier Reef off the coast of Australia. The unique geological formation was under threat of destruction. The fight against the crown of thorns was complicated by the fact that its thorns are poisonous to humans, the prick of the crown of thorns causes burning pain, although it is not fatal. Specially trained divers collected acantasters with sharp peaks in bags or injected a lethal dose of formalin into the body of a starfish. Only in this way was it possible to pacify the invasion of voracious predators and save the reef. Nowadays, all types of starfish are in good condition and do not need protection.

The crown of thorns eats up the coral.

It turns out that there are stars not only in the sky, but also under water. And it is worth noting that underwater stars are much more varied and more beautiful than celestial ones. Moreover, they are also alive! Yes, the starfish is an animal. All types of starfish belong to the class of invertebrates and are representative of the type: "echinoderm".

The structure of starfish

As the name suggests, this creature has a structure similar to the generally accepted image of a star - i.e. five-pointed figure. The system of the body structure of this animal in the scientific world is called "ambulacral".

Its essence lies in the fact that inside the starfish has channels and cavities in which water is located. By pumping liquid from one part of the body to another, the starfish moves. In addition to an interesting shape, the animal has thorny thorns on its body. The mouth is in the center of the lower body (abdomen).

The starfish breathes with the help of skin outgrowths, because nature has not provided this creature with gills and lungs. Because of this respiratory characteristic, the animal suffers greatly when there is not enough oxygen in the water.

On the other hand, the starfish boasts a fairly good digestive system, consisting of two stomach sacs, and an excellent ability to regenerate.

These creatures are different in size - from the smallest (1.5 cm) to decent (90 cm). The starfish lives for 20 years, and sometimes more.

Spread on the planet

These wonderful inhabitants of our planet inhabit almost all seas and oceans. They can only live in salt water. Starfish live even in northern waters, despite the low temperatures. Although there are many more of them in warm seas.

Lifestyle

Basically, the starfish is a shallow-water animal, although there are deep-sea inhabitants among the representatives of this species. Sometimes starfish are found at depths greater than 9000 meters

Animals move along the bottom, very slowly - only 10 centimeters per minute. If necessary, the starfish can "add speed" and "accelerate" up to 30 centimeters per minute.

Diet

Despite its natural beauty and attractiveness, the starfish is a real predator. It feeds on worms, molluscs, and small invertebrates. In addition, some stars can eat plankton and detritus.

How starfish breed

Representatives of this species of invertebrates are mostly dioecious. Their sex glands are located at the base of their legs (rays). Some starfish can have sex glands of both sexes, and sometimes (in some species) they can even change sex (from male to female).

Mating takes place by connecting beams. During this process, male reproductive cells and caviar are swept into the water. As a result of fertilization, after a certain period of time, small larvae are born.

A feature of some representatives of sea stars is considered to be the ability to reproduce asexually, namely, by division! The body of one star is divided into two parts, and each of them begins to develop and grow independently.

Even if this animal is taken and divided into parts by hands, then it will also multiply. Only because of the slow growth, one leg (from which the development of a new individual will begin) will be longer than the others for a long time.

The name of this starfish speaks for itself - elegant fromia (Fromia elegans)

Do these beautiful underwater creatures have enemies?

Undoubtedly there are, but there are not so many of them. Large predators do not really want to hurt themselves on the thorny thorns of the star.

And the stars themselves, seeing the enemy, try to bury themselves deeper in the sand as soon as possible. Among the natural enemies of sea stars, gulls and sea otters predominate.

The use of starfish by humans

Some species of these invertebrates are eaten by the Chinese, although not often.

These animals do not represent any more interest for humans, except for aesthetic. Perhaps, they were created by nature in order to simply admire them and get a lot of positive emotions from this.

Starfish asteria (Asterias rubens) pulls a hand towards a clam

Many questions arise, among which the following are of particular interest: "What does the starfish eat?", "For whom does it pose a mortal threat?"

Stars on the seabed

These extraordinary decorations of the seabed have existed on the planet for a long time. They appeared about 450 million years ago. Up to 1600 types of stars are distinguished. These animals inhabit almost all the seas and oceans of the earth, the water of which is quite salty. Stars do not tolerate desalinated water, they cannot be found in the Azov and Caspian Seas.

Rays in animals can be from 4 to 50, sizes range from several centimeters to a meter. The lifespan is about 20 years.

Sea inhabitants do not have a brain, but there is an eye on every ray. The organs of vision resemble insects or crustaceans; they distinguish between light and shadow well. Many eyes help animals to hunt successfully.

Stars breathe practically through the skin, so it is very important for them to have a sufficient amount of oxygen in the water. Although some species can live in decent ocean depths.

Structural features

It is interesting how sea stars reproduce, how they feed. Biology classifies them as invertebrates, echinoderms. The starfish has no blood as such. Instead, the star's heart pumps sea water through the vessels, enriched with some trace elements. Pumping water not only saturates the cells of the animal, but also by pumping liquid in one place or another helps the star to move.

Starfish have a ray pattern of the structure of the skeleton - rays depart from the central part. The skeleton of sea beauties is unusual. It is composed of calcite and develops inside a small star from practically a few calcareous cells. What and how starfish eat depends largely on the features of their structure.

These echinoderms have on their tentacles special pedicellaria in the form of tweezers at each tip of the outgrowth. With their help, the stars hunt and clean their skins from the litter that has clogged between the needles.

Sly huntresses

Many people are interested in how starfish eat. Briefly about the structure of their digestive system can be found below. These amazing beauties give the impression of perfect safety. In fact, they are marine predators, voracious and insatiable. Their only drawback is slow speed. Therefore, they prefer a stationary delicacy - mollusk shells. With pleasure, the starfish feeds on a scallop, is not averse to eating a sea urchin, trepang and even a fish that has inadvertently swam too close.

The fact is that the starfish has practically two stomachs, one of which can turn outward. A careless victim, seized by pedicellaria, is transferred to the mouth opening in the center of the rays, then the stomach is thrown over it, like a net. After that, the hunter can release the prey and slowly digest it. For some time, the fish even drags its executioner with it, but the victim cannot escape. Everything that a starfish eats is easily digested in its stomach.

She behaves somewhat differently with shells: she slowly approaches the dish she likes, braids the shell with her rays, places the mouth opening in front of the shell slit and begins to move the flaps apart.

As soon as at least a small gap appears, the external stomach is immediately pushed into it. Now the sea gourmet calmly digests the host of the shell, turning the mollusk into a jelly-like substance. Such a fate lies in wait for any eaten prey, it does not matter whether the starfish feeds on a scallop or small fish.

Features of the structure of the digestive system

The predator lacks any devices for capturing prey. The mouth, surrounded by an annular lip, connects to the stomach. This organ occupies the entire interior of the disc and is highly flexible. A gap of 0.1 mm is enough to penetrate the shell valves. In the center of the aboral side, a narrow short intestine opens, extending from the stomach. What a starfish eats depends largely on the unusual structure of the digestive system.

The love of the stars at the bottom of the ocean

Most starfish are heterosexual. During love games, individuals are so busy with each other that they stop hunting and are forced to fast. But this is not fatal, because in one of the stomachs these sly ones in advance try to put aside nutrients for the entire time of mating.

The sex glands are located at the stars near the base of the rays. When mating, the male and female individuals connect the rays, as if merging in a gentle embrace. Most often, caviar and male reproductive cells enter the sea water, where fertilization takes place.

In the event of a shortage of certain individuals, stars can change sex to maintain a population in a certain area.

The eggs of these usually remain on their own until the larvae hatch. But some stars turn out to be caring parents: they carry caviar on their backs, and then larvae. In certain species of starfish, for this, during mating, special caviar bags appear on their backs, which are well washed with water. There she can be with the parent until the larvae appear.

Reproduction by division

An absolutely extraordinary ability of sea stars is reproduction by fission. The ability to grow a new hand-ray exists in almost all animals of this species. A star, seized by a predator by the beam, can throw it away like a lizard's tail. And after a while, grow a new one.

Moreover, if a small particle of the central part remains on the beam, a full-fledged starfish will grow from it after a certain time. Therefore, it is impossible to destroy these predators by cutting them into pieces.

Who are the starfish afraid of?

The representatives of this class have few enemies. Nobody wants to mess with the poisonous needles of sea dwellers. Animals are also able to secrete odorous substances to scare off especially voracious predators. In case of danger, the star can bury itself in silt or sand, making it almost invisible.

Among those who feed on starfish in nature, seabirds prevail. On the shores of warm seas, they become prey for gulls. In the Pacific Ocean, funny sea otters are not averse to feasting on a star.

Predators harm underwater plantations of oysters and scallops - what the starfish feeds on. Attempts to kill animals by chopping them apart led to an increase in the population. Then they began to fight with them, bringing the stars to the shore and boiling them in boiling water. But there was nowhere to use these remains. There have been attempts to make fertilizer from animals, which at the same time repels pests. But this method was not widely used either.

Which are planted for harvesting, and there are those that are used as living decorative ornament.

The latter include sycamore tree, which in the East is called plane tree.

Sycamore varieties

Today there are 10 types of sycamore trees that grow all over the world. The most popular are the following:

Ordinary. It is a hybrid of western and eastern species. It grows up to 40 m. It has a wide trunk and a rounded crown. Most common in Europe and America.
West. It grows in North America. Refers to deciduous trees. Height - no more than 35 m. Withstands frosts down to -35 ° С. Needs constant watering, as it does not tolerate drought.
Oriental. Grows in the Caucasus. A long-liver who is growing fast enough. Edible fruits, they are called "plane trees".
Maple-leaved plane tree. An unusually large and majestic tree that grows up to 30 m. It can be grown in temperate climates and tolerates low temperatures well. A distinctive feature is the flaking of the bark of different sizes, and as a result of the appearance of spots.

Did you know? The oldest and largest plane tree on Earth grows in Turkey. Its height is more than 50 m, and its age- more than 2000 years.

Seeing at least once a plane tree in all its glory, many have a desire to admire it many more times, for this they begin to look for information on how to grow a plane tree from seeds in their area.

Growing from seed in a pot

This method is the most popular, since in this state the seedlings can be kept in any convenient place, providing them with constant care and supervision. This will allow, if any deviations in development appear, immediately get rid of the problem without losing the seedling. For the result to be positive, you need to know some of the nuances.

Requirements for planting material

Having made the decision to cultivate by seed, it is important to know that if all storage rules are followed, the seeds retain the ability to germinate throughout the year.

Seed preparation

Before sowing, the seeds must be hardened and disinfected. For this, the pre-assembled material is placed in a cotton bag and deepened 50 cm into the ground. These manipulations are done at an air temperature of at least + 10 ° C. If the temperature is lower, you need to prepare the container, fill it with clean sand and place a bag of seeds there. The container is placed in a basement or other place where the temperature does not drop below 10 ° C.

Sowing depth

After hardening is complete, when the temperature begins to rise, the seeds are removed and prepared for planting. To do this, they are soaked in water for several days, and then the hatched seeds are planted in selected containers in pairs to a depth of 2 cm.

Important! To increase the number of germinated seeds, they can be soaked in a solution of potassium permanganate 0.25% for half an hour. For its preparation, 2.5 g of powder is diluted with 1 liter of water.

Conditions and care of crops

For good growth, the temperature in the room where the containers with seedlings are located should be at least 25 ° C. Water as needed, making sure that the earth does not dry out. During the entire period of seed germination, it is important to ensure that direct sunlight does not fall on the ground and sprouts.

Planting seedlings in open ground

Planting seedlings in the ground does not require compliance with any requirements. The sycamore tree is unpretentious in its content and this makes it easy to grow, even for novice gardeners.

Optimal timing

You can plant seedlings in spring and autumn. Regardless of the time of year, compliance with all the rules will allow the tree to fully take root. The main thing is to remember that in spring it is recommended to plant it in dense soil, and in autumn, on the contrary, in loose soil.

Seat selection

It is not recommended to plant plane trees close to buildings, as a powerful root system can damage communications and even the foundation. The land should be located in an area where there is a lot of light, since the tree is light-loving.

In order for the plane tree to grow normally and please with its beauty, you need to follow some simple rules for care, which include moistening the soil, cutting off excess or damaged branches, and even creating conditions for wintering.

Watering

Moisture and light are the main requirements of this plant. Rational watering makes it stand out from other garden dwellers. In dry times, the amount of water should be higher. Only in this case, growth will not slow down and the leaves will be green.

Top dressing

For these giants, it is important only at a young age. This should only be resorted to when the soil does not meet the requirements. Well aerated, rich in mineral and organic elements are introduced into the soil. Ideal option - use universal complex fertilizers, the main thing here is not to overdo it.

Pruning

The western sycamore and other species are quite thermophilic, nevertheless, they also tolerate cold weather well. To obtain a tree with a spherical crown, pruning is required, and even large branches if they are knocked out of the general picture.

Wintering

For a successful wintering of a tree, it is important to worry about which may consist of coniferous branches, or leaves. They are poured around the tree trunk, creating an embankment up to 30 cm.

Propagation by cuttings

This breeding method is challenging but possible. The workpieces are carried out as follows:

At the end of the fall, cuttings are cut 40 cm long, the thickness of the branches should be at least 2 cm.
Collect them in small bunches and place them in a bucket of water.
They put it in a cool place until spring.
After swelling of the buds, the branches are planted in a permanent place.

Important! At the time of planting the cuttings in the ground, you need to add a small amount of washed sand, which is necessary for the normal growth of the tree.

The cutting is deepened by 2/3 of the length. The ground part is tilted 45 °.
Water thoroughly and wait for rooting.

The use of plane trees

Previously, the sycamore was used only to create shade in the scorching sun. Today, its wood is prized in the design of car interiors, in the manufacture of furniture and many other items, and even as a medicine in traditional medicine.

In landscape design

The plane tree is used as a decoration for parks, gardens and squares. It not only creates a large area of shadow that forms under its crown, but also decorates any area. The main thing when choosing a species is to measure the size of the land and the future height of the tree.

Did you know? The plane tree has been known since the times of Ancient Egypt, where he was revered as the god of the sky. He was also planted in Ancient Greece, Sparta and the Roman Empire.

In folk medicine

Chinara is used as a hemostatic, analgesic and anti-inflammatory agent. For example, a decoction of the roots is used as a remedy for diarrhea. To do this, you need to take the bark of the trunks of young trees. Infusion of leaves is used for conjunctivitis.