How many hearts does a starfish have? The most beautiful starfish in the world
Starfish are one of the ancient forms life, their age is 600 million years.
Starfish are characterized by symmetry.
A feature of all echinoderms is their water-vascular system, which runs through the entire body in the form of canals that protrude through the pores of the calcareous exoskeleton, forming
tube feet, and represent the external manifestations of the system. These legs perform various functions. The type, which evolved about 600 million years ago and all fossil forms are believed to have the same water-vascular system, which is no longer found in any animal species.
Starfish typically spend the spring in shallow waters and move deeper in the winter.
During the breeding season, the gonads of sea stars produce a poison designed to protect the eggs. This slimy, toxic secretion that the starfish releases into the water paralyzes snails, bivalves and shrimp. The poison also has an antibiotic effect and protects the eggs from microorganisms that are found in seawater.
Starfish can move at speeds of up to 75 cm per minute.
The largest of the 1,600 species of starfish in terms of total tentacle span is considered to be the very fragile Midgardia xandaros. In the summer of 1968, a representative of this species was caught in the southern Gulf of Mexico by the University of Texas research vessel Adaminos. Its length together with tentacles was 1380 mm, but the diameter of its body without tentacles reached only 26 mm. When dried, it weighed 70 g.
It is believed that Weight Limit Of all the sea stars, the five-pointed Thromidia catalai, which lives in the western part, has Pacific Ocean. A representative of this species, caught on September 14, 1969 in the Ilot Amedi area in New Caledonia and later exhibited in the Noumea Aquarium, weighed 6 kg, and the span of its tentacles reached 630 mm
The smallest known was the asterenid starfish (Patmella parvivipara), discovered by Wolf Seidler on west coast Eyre Peninsula, South Australia, in 1975. It had a maximum radius of 4.7 mm and a diameter of less than 9 mm.
The most predatory sea star in the world is considered to be the “Crown of Thorns” (Acanthaster planci), which lives in the Pacific and Indian Oceans, as well as in the Red Sea. It has the ability to destroy up to 300-400 square centimeters of coral per day.
The maximum depth at which a marine aveada can be found is considered to be a depth of 7584 m. At this depth, the Soviet research vessel Vityaz approximately 1962 in the Mariana Trench ( West Side Pacific Ocean) a specimen of Porcellanaster Ivanovi was discovered.
Starfish - animals with unusual shape body, thanks to which they attracted the attention of people back in ancient times. Starfish belong to the phylum Echinodermata, in which they are classified as a separate class, numbering almost 1,600 species. The closest relatives of these invertebrates are brittle stars, or snaketails, which are very similar to them, and more distant relatives are sea cucumbers and sea urchins.
Elegant starfish (Fromia monilis).
The main distinguishing feature of starfish is, of course, their body shape. In general, the body of starfish can be divided into central part- 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 starfish there are organisms with a large number axes of symmetry: in some species their number can reach 6-12 and even 45-50.
Nine-armed starfish (Solaster endeca).
Each sector, accordingly, includes part of the central disk and a hand. It would seem that such a similar structure should result in the monotony of these living organisms. But the body shape of starfish is very variable. Firstly, 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 disk. The latter type of stars have a very high central disk, so they resemble pillows. Thus, in most species of sea stars, the length of the rays is 3-5 times greater than the diameter of the central disk, in the longest-armed ones it is 20-30 times, and in the cushion-shaped ones it tends to zero.
This bright ottoman seabed in fact, the New Guinea culcita starfish (Culcita novaeguineae).
Secondly, sea stars differ in surface texture and color. Here the variety simply defies description - smooth, spiky, 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, and black. Pale sea stars usually live in the depths, while shallow-water species are brightly colored.
This is the same New Guinea kulzita, but of a different color.
At first glance, starfish seem primitive, because they do not have any noticeable sensory organs, a brain, and are poorly differentiated internal organs, but this simplicity is deceptive.
The Linkia starfish (Linckia laevigata) is bright blue in color and has sausage-like rays.
First of all, it should be noted that starfish have internal skeleton. They do not have a backbone or individual bones, but have many calcareous plates connected to each other in an openwork system.
Openwork plexuses of skeletal elements on the surface of a starfish.
In a young starfish, the skeletal elements are hidden under the skin, but over time the skin over some calcareous spines wears off and they become visible from the outside. It is these spines that give starfish their spiny appearance.
The spines 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 may be visible, fused together or forming a network.
A bizarre pattern formed by the skin and skeletal elements of a starfish.
Finally, the third element influencing appearance starfish are pedicellaria. Pedicellariae are modified needles that look like tiny tweezers. In the life of a starfish they play important role, with their help she cleanses the upper side of the body from debris and sand. All skeletal elements are connected to each other by muscles, so after the death of a starfish, its skeleton crumbles into calcareous plates and not a trace remains of the animal.
The acanthaster starfish, or crown of thorns (Acanthaster ellisii) has spiny and poisonous spines.
The muscular system of starfish is relatively poorly developed. Each ray has a muscle cord that can bend the ray upward, and this, in fact, limits the muscle movements of the stars. But mobility is not limited at all. Starfish can crawl, dig, bend, and swim, but they do not do this with the help of muscles.
Scalloped sea stars (Patiria pectinifera) climb on the seaweed.
These animals have a special body system - ambulacral. Essentially, this system consists of channels and cavities connected together and filled with liquid. The starfish can pump this fluid from one part of the system to another, causing its body parts to flex 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 perform miracles. For example, it is able to climb a vertical surface, can stick to the glass of an aquarium for a long time, can rear up, swelling up like an angry cat, or maybe, grabbing hold of two rays, push the valves of a 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.
To be fair, it is worth noting that starfish do have some sense organs. These are the eyes located at the ends of each ray. The eyes are very primitive and only distinguish between light and darkness; starfish cannot see objects. Starfish are capable of catching chemical substances(analogous to smell), only they feel them differently. Some species are very sensitive and can crawl to the bait for several days in a row by smell, while others can crawl past the victim a couple of centimeters and not smell it. Sea stars have a very developed sense of touch; they try to get rid of the sand that covers them from above, and also always try to feel their way with the help of small tentacles at the end of each ray. The sense of touch tells the starfish whether it has encountered a victim or a predator. The starfish's brain is replaced by a group of loosely interconnected cells. What is surprising is that despite such a primitive structure nervous system starfish can produce elementary conditioned reflexes. For example, individuals who were often caught in 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 asterodiscus starfish (Asterodiscus truncatus) a formed eye is visible. The beam itself is covered with relief limestone plates.
Another strong one, directly and figuratively words, the system of starfish is the digestive system. The mouth of these animals is located in the center of the disc on the underside of the body, and the tiny anus is located on the back. By the way, starfish rarely use it (in some species it even becomes overgrown), preferring to remove undigested food residues through the mouth. The stomach of these invertebrates has outgrowths extending into rays; reserves of nutrients are deposited in them in case of famine. And starfish regularly starve because they stop feeding during reproduction. The stomach in many species can turn outward through the mouth opening, and it stretches like rubber, taking any shape. Thanks to its expandable stomach, the starfish can digest prey that is larger than itself. There is a known case when the starfish Luidia swallowed such a large sea urchin that it died, unable to spit out its remains.
A tiny anal opening is visible in the middle of the central disc of Phromia monilis.
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 do not have gills or lungs, so starfish are sensitive to lack of oxygen. They also cannot tolerate desalination of water, so they are found only in seas and oceans. The sizes of these animals range from 1-1.5 cm for the miniature spherical star Podosferaster to 80-90 cm for the sea star Freyella.
The name of this starfish speaks for itself - fromia elegans.
Starfish have a global distribution. They are found everywhere in all seas and oceans from the tropics to the poles. Of course, in warm waters species diversity higher than in cold ones. Most species prefer to live in shallow waters, some even end up on the shore during low tides. But among these animals there are also deep sea species, including those that live at depths of over 9 km!
Starfish in shallow water.
Sea stars most time crawling along the bottom. They do this very slowly, the usual speed of a medium-sized individual is 10 cm per minute, but a starfish can “hurry up” at a speed of 25-30 cm per minute. If necessary, these animals climb onto stones, corals, and algae. If a starfish falls on its back, it immediately turns over ventral side down. To do this, the animal bends two rays so that the ambulacral legs on the lower side touch the ground, and then the starfish turns its body and takes its usual position. Some species are even capable of swimming awkwardly over short distances. Starfish 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.
Despite their outward primitiveness and apparent helplessness, starfish formidable predators. They are quite voracious and never refuse prey, with the exception of the period of gestation. Only deep-sea species feed on silt, from which they extract food particles; kulcite sea stars, which prefer to eat fouling on corals, can also be called conditionally “non-predatory”. All other species actively hunt other animals.
Not at all romantic relationship connected this pair: the sea star Solaster dawsoni eats the spiny hippasteria spinosa.
Most starfish are picky; they eat everything they can hold with their hands and whatever their “rubber” stomach can reach, not disdaining carrion. Some species can only feed a certain type food: sponges, corals, gastropods.
The pretty starfish (Pentagonaster pulchellus), also called the biscuit starfish for its biscuit-like body shape.
The favorite prey of sea stars are sedentary animals like themselves - sea urchins and bivalves. The star catches the sea urchin by crawling and eats it with its mouth. Bivalves They have shells whose valves close tightly in case of danger, so starfish treat them differently. First, the starfish sticks with two rays to the shell flaps, and then begins to move them apart. It must be said that the ambulacral legs are firmly glued to the substrate thanks to an 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 apart with an effort of several kilograms. However, the starfish does not need to spread the shell flaps to their full width; for a hearty lunch, a gap of 0.1 mm is enough for it! The starfish turns its stomach into this truly microscopic gap (it can stretch up to 10 cm) and digests the mollusk in its own home.
Asteria starfish (Asterias rubens) reaches out to a clam.
Most starfish are dioecious; very few species have both male and female gonads. The gonads are located in pairs at the base of each ray. In the asterine starfish, the young are first male and then change to female. A special exception is the ophidiaster starfish, which has no males at all! Females of this species lay eggs without fertilization, a process called parthenogenesis. During mating, males and females connect their rays and release sperm and eggs into the water. The number of eggs depends on the type of development of the larvae and ranges from 200 in those species that bear offspring, and up to 200 million in species with free-swimming larvae.
Mating starfish.
Starfish larvae come in three types. In some species, the eggs hatch into a free-swimming larva, 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 that live 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 rests only on the tips of the rays, and arches her body into a dome, under which the offspring are located. Since the larvae are located near the mouth opening, the female does not feed during this period. The larval form is most mobile in life cycle starfish, it is during this period that young animals 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-rayed species; the body of the animal is divided into two halves, each of which builds up the missing rays. In other species asexual reproduction may be the result of regeneration following 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 beam is enough for restoration, but a piece of the central disk is required. Starfish grow slowly, so they look lopsided for many months.
A new individual is formed from the cut off ray of a starfish. This shape is often called a comet.
IN natural environment starfish have very few enemies, since the sharp spines, which can be poisonous, scare away 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 fall into the teeth of sea otters and seagulls.
A seagull caught a starfish.
But the starfish Astropectenus is friends with polychaete worms. One individual can have up to five cohabitants, who prefer to stay on the underside of the body close to the star’s mouth. The worms pick up the remains of her prey and even stick their heads into her stomach! Ctenophores live on the starfish Echinaster special type, which clean the surface of the star from fouling.
These bright spots on the Luzon starfish (Echinaster luzonicus) are ctenophores (Coeloplana astericola).
Since ancient times, people have paid attention to the colorful animals of shallow waters, but starfish were of no economic interest to them. Only in China are they sometimes eaten, while attempts to feed starfish to domestic animals can lead to the death of the latter. This is likely due to toxins that some species accumulate by eating coral and poisonous shellfish. But with the development of the maritime economy, people began to classify these animals as their enemies. It turned out that starfish often eat bait in bottom traps for crabs, and also raid plantations for breeding oysters and scallops. In a few years (that’s how long it takes to grow oysters), starfish can destroy an entire oyster bank. At one time they tried to destroy the predators by cutting them into pieces, but this only increased their numbers, because from each stump a new starfish grew. Then they learned to extract starfish with special trawls and kill them with boiling water.
A very impressive mosaic starfish (Iconaster longimanus).
The most a malicious pest It turned out to be an acanthaster starfish, or crown of thorns. This very large echinoderm feeds exclusively on corals; after itself, the crown of thorns leaves only a white lifeless path on the coral reef. At one time these stars multiplied so much that in literally words ate a huge section of the Bolshoi 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; crown of thorns causes burning pain, although not fatal. Specially trained divers collected acanthasters with sharp peaks into bags or inserted them into the body of a starfish lethal dose formaldehyde. This was the only way to pacify the invasion. voracious predators and save the reef. Nowadays, all species of starfish are in a safe condition and do not need protection.
The crown of thorns eats the coral.
When you see a starfish for the first time, the first thing that comes to your mind is that it’s an ordinary souvenir, but in fact it’s Living being, which looks like a star. With its way of life, this entity seems to ignore all the usual laws of biology - having neither blood nor brain, stars have unique eyes and can digest food outside of their body.
External features of starfish
Starfish are invertebrate, nearly symmetrical animals that are found in all oceans. They appeared approximately 500 million years ago. Most of the representatives of this species are found not at the bottom, but almost on the surface, but there are stars that are found at a depth of 6000 meters. Today, zoology describes more than 1,800 species of starfish. Each species has its own characteristics, but all representatives are united by the correct symmetrical shape and row external features, which prevents them from being confused with any other species.
Typically, stars have five or six rays that emanate from the center of the disk. The record number of rays that zoologists have recorded is 50; at great depths, representatives of the species with 10-15 rays are found. In starfish, the body length can reach one meter, but the most characteristic size is 15-25 centimeters. Large stars can weigh 5 kilograms; they are also called “solar stars”. These types of animals are more powerful; they have enough power to tear apart the shells of crustaceans. They hunt their prey and can even pursue it for a long time.
Starfish have a rough or smooth surface and may be covered with ridges or sharp, poisonous needles. Some of the representatives of the starfish family have very bright colors and are extremely beautiful; it is impossible not to notice their presence in the water. The color range of starfish includes all shades and colors. Bright stars live close to the surface, while pale ones, as a rule, live at great depths.
Feeding starfish
As for the nutrition of starfish, their diet is quite varied - they do not hesitate to feast on carrion, they eat sea urchins, which is several times larger than them, and crabs can even attack small fish. Moving along the bottom, they dig small holes and there they wait for their prey, which inadvertently approaches the mouth opening of the star. The feeding process itself is very interesting: the star drags its stomach out and envelops its victim in it. During the eating process, special enzymes are released that help digest food not inside the star, but outside.
Starfish have a very flexible stomach; it only needs 0.1 mm to penetrate the gap. It is for this reason that mollusks only need to open their valves a little, and the starfish will already envelop them with its stomach and eat it. The eating process can last up to 8 hours, everything happens very slowly, but in general the feeding time depends on the size of the victim. In the industry, the starfish is considered the real enemy of oysters due to the reasons described above. In order to limit the contact of starfish with oysters, they are systematically removed using nets.
Regenerative abilities and reproduction
In many scientific videos, the starfish regrows lost organs and is completely restored if at least half of the disk or lost ray is present. There are scientific cases where a fallen limb completely restored the entire disc. There are also species of starfish that reproduce this way - by fission.
Also present in the species sexual reproduction. Men's and females They release their eggs into the water, and fertilization occurs outside the body. No matter how strange it may sound, one female starfish can become the mother of two million larvae. After fertilization, the larvae mix with ordinary plankton, but when they mature, they settle on the bottom and lead independent life. Some species of stars hatch larvae in their stomach or under a plate. But, this is rare; in most cases, fertilization occurs outside the female’s body.
Internal skeleton and muscles
Initially, it may seem that in the absence of olfactory organs and a brain, these are primitive animals, but such simplicity is very deceptive. As the scientific video shows, starfish have a skeleton. Of course, skeleton stars do not consist of a backbone, but they have calcareous plates connected to each other in an openwork system.
In young organisms this openwork system is not visible, but with age the skin wears off and the skeleton begins to appear outward. It is the protrusion of the skeletal plates that makes the starfish spiny. Some calcareous plates that protrude outward merge together and create the appearance of tentacles. With their help, starfish cleanse outer part its plate from sand and various garbage. After a starfish dies, its skeleton crumbles and all that remains is dust. Some starfish have tentacles that are poisonous and serve additional means hunting for small fish and crustaceans.
Concerning muscular system, then, as the scientific video shows, starfish can move, swim, bend, but all this is not with the help of muscles. They are very weak in this species of animal. All the muscle can do is lift the beam upward.
Some of the starfish can even climb up algae; such movement is achieved thanks to the ambulacral system of the body. The system consists of cavities and channels that are filled with liquid, which the star can distill into different parts of its body and thus move. Main feature This system is that it provides small legs on the underside of the star plane. The tiny outgrowths move individually, but in most cases all movements are coordinated and rhythmic. Thanks to these small legs, the starfish can rear up, stick to vertical planes, and even tear the shell of a mollusk with two rays.
Sense organs of starfish
Starfish completely lack all sense organs, except for the eyes, of course. The eyes are located at the tip of each ray. Starfish do not distinguish objects and colors; their eyes are very primitive, so they only recognize light and darkness.
An analogue of the sense of smell in these animals is the ability to capture chemical substances that are present in the water with their body. Animals move not using their eyes, but using their sense of touch. They feel their way in the sand, and with the help of the same sense of touch, they understand who they encountered on the road, a predator or prey. Note that all this happens in the absence of a brain. Starfish have brains that are tightly connected to each other nerve cells. It is very surprising that in the absence of a nervous system, as the scientific video shows, starfish are still capable of conditioned reflexes. For example, individuals that have repeatedly been caught in nets are freed much faster than those that have gotten there for the first time.
Distribution area of starfish
Starfish can't stand fresh water, therefore they are found only in seas and oceans, where salty water. They move very slowly, on average 10 centimeters per minute. They can climb rocks, seaweed and coral. A very interesting fact is that, unlike turtles, which, having fallen on their backs, cannot turn over on their own, starfish immediately return to their usual position.
This species of animal can be safely classified as sedentary; in its entire life it is unlikely that it moves further than 500 meters from its birth. In their usual habitat, starfish have virtually no enemies. The spiny structure of the body is intimidating large predators, so they are quite quiet life, but can sometimes fall into the mouths of seagulls and sea otters, which mistake them for fish.
Vibrant inhabitants depths of the sea, people have noticed for a long time, but starfish do not have any economic use, only in China they are occasionally eaten. Starfish are very sensitive to high temperatures, and you can kill them simply by pouring boiling water on them. Many starfish are poisonous, so it is not recommended to pick them up with bare hands. This once again proves how changeable nature can be - such a beautiful and at first glance harmless creature can deprive big man life in one minute.
You can even see these and other inhabitants of the underwater world in person!
What do you know about starfish? Beautiful and unusual creatures, with many interesting facts from their life - in our selection. Currently, about two thousand species of starfish are known.
Starfish do not have a brain or blood - to obtain nutrients, oxygen and other important fluids, the starfish pumps sea water through its body. It is the resulting water that is distributed throughout the body and forms the “water-vascular system.”
On each arm of a starfish, mistaken for tentacles, there are about 15 thousand tiny suckers that help the starfish move.
A starfish is not a fish, but an invertebrate animal.
Starfish are true predators. They are capable of attacking their own kind and can easily feast on the small offspring of their own species, i.e. are cannibals.
Stars have two stomachs, one of which they can even push out to digest shellfish.
Starfish are long-lived, some species live up to 30-35 years.
Many of the starfish are very dangerous. For example, the crown-of-thorns starfish, which is distributed throughout the Indo-Pacific Ocean, is covered in venomous spines. Growing to almost half a meter in length, these creatures become dangerous not only for coral reefs, but also for divers and swimmers.
Starfish can easily change gender and then switch back. True, for such “transformations” you need several suitable conditions - quality water, temperature and food availability.
Starfish have eyes - exactly as many as there are rays; at the tip of the rays there is an eye, which looks like a red spot. They don't see very well, of course, but at least, distinguish between darkness and light.
Even though starfish live underwater, they do not have gills.
Although the appearance of most starfish corresponds to their name, sometimes unusual individuals with bizarre shapes are found. For example, starfish may have a sun-shaped shape, multiple rays, or their shape may be rounded.
The heart of starfish beats at a frequency of 5-7 beats per minute.
The largest starfish can reach 1 meter in diameter and their weight can reach 5 kilograms. solar stars more active than their relatives, and are able to quickly pursue their prey, and, having incredible strength, simply tear the shell of mollusks and crustaceans.
The feeding method that allows the starfish to eat prey much larger than the mouth opening is as follows - since the starfish's mouth is on the underside of its body, the star, having grabbed the prey, wraps its Strong arms around it, and then with a strong push he places it under himself, and then pushes it into the stomach.
They are also some of the most ancient inhabitants of the Earth. Starfish are about 250 million years old.
Stars move using hundreds of tubes that are attached to the surface and then move in waves.
Starfish live at various depths, up to ten kilometers
In the last few years, starfish have begun to actively reproduce. This creates a problem, because each individual has an excessive appetite and consumes about 6 square meters corals per year. In some areas, measures are being taken to destroy stars.
However, starfish still bring much more useful than harmful - they are important consumers carbon dioxide– every year, starfish collectively destroy about 2% of the Earth’s carbon dioxide, and this is an extremely large figure for the entire planet.
Another useful role of starfish is cleaning seabed from carrion, weak and sick creatures of the seabed, as well as from the remains of dead oceanic organisms.
Starfish go through five stages of growth before becoming adults - during the first month, stars are free-swimming and jellyfish-like, they are small, almost invisible to the eye and tiny plants and animals of the ocean.
Although most sea stars are not poisonous, a large star called the acanthaster or crown of thorns is dangerous to humans. The pricks of its needles bring burning pain to a person - if the needle gets stuck in the skin, then it breaks off from the star’s body and begins to infect the person’s blood with poisonous secretions.
An interesting fact is that if you cut off one of the arms of a starfish or all of them at once, without damaging the central part of the body, they will gradually grow back.
Star shape
The name “starfish” immediately brings to mind the traditional five-pointed starfish that we commonly see in the water, but star shapes can come in many different forms. There are also sun-shaped stars with rounded bodies and numerous rays. The largest sea stars in the Pacific Northwest can reach 1 meter in diameter and weigh up to 5 kilograms, and have up to 20 arms. Sunstars are more active than many other species and are capable of swift pursuit of prey. They are strong enough to tear the shells of mollusks and crustaceans. Such stars can form numerous groups in particularly food-rich areas.
No blood or brains
Starfish are complex and strange creatures in many ways, but their bodies are also quite primitive. They have a perfectly adapted digestive system and exceptionally advanced skin, but at the same time obvious drawback in the brain and the absence of any blood. Lacking blood flow and gills, the starfish lives by pumping seawater through its body. So she gets nutrients, oxygen and others important fluids. As a replacement for blood, seawater is distributed throughout their body through the so-called “water vascular system.” Sea water spreads throughout the body mechanically, using muscles and lymph glands. At the same time, the entire system works with maximum efficiency, even without the presence of blood. The body of a starfish is still shrouded in mystery, and we don't fully understand how it functions. Scientific research on the starfish body remains one of the most interesting tasks for scientists.
Starfish suckers
You probably thought that a starfish had tentacles, but in fact, the correct name for them is arms. Take a close look at the underside of a starfish and you'll discover that each arm may have up to 15,000 tiny suckers, which it uses to propel itself very efficiently. During high tides, the suckers allow the star to cling to the rocks, otherwise the waves could break them to pieces. The soft underbelly of the star will hug the rock, while the upper part of the star is covered with tough skin. Scientific research constantly discovering new ones amazing facts about starfish, and in the future we will definitely learn the secret of their magical suckers.
Cannibalism
Most of us think of starfish as the bright pearls of the ocean, but in reality they are more of a greedy predator. You will be surprised to know that cannibalism is a well-documented fact of life for these strange creatures. This cannibalistic behavior is often caused by a reduction in normal food supplies. They are very well equipped to attack their own species. Certain starfish do not mind feasting on the small offspring of even their own species.
Two stomachs
Starfish may look attractive, but they are actually greedy predators with two stomachs. One of the most bizarre features is their ability to remove the stomach. Using water pressure vascular system, one of the stomachs may be pushed out to digest shellfish. After the starfish opens the shell of its prey, it places it in this external stomach. It digests the victim in its shell and turns it into a liquid soup. The stomach is then returned to the starfish for the second stage of digestion. This is a rather complex mechanism with numerous extensions of the intestinal system that distributes nutrients throughout the body. All digestive process The sea star is one of the most incredible examples of evolutionary progress, especially considering how primitive these creatures are in other respects.
crown of thorns
There are very dangerous species starfish. Distributed throughout the Indo-Pacific Ocean, the crown-of-thorns starfish is covered in venomous spines. They are dangerous not only for divers and swimmers, but also for coral reefs. These creatures can reach almost half a meter in length, threatening the ocean ecosystem. The doubling of phytoplankton levels resulted in a 10-fold increase in the population of these animals. Changing ocean temperatures and currents, as well as a decline in natural predators, have also been cited as potential factors. sharp increase populations. A small population of this star contributes to the diversity of the reef as it feeds on fast-growing acropoid coral. This gives slow-growing corals a chance to establish themselves. On the other hand, the spines of these echinoderms can cause significant damage coral reefs. One of the most serious cases involves damage to the Great Barrier Reef. The 50% decline in total coral cover on the reefs reviewed over the past 30 years has been extensively studied. It turns out that half of this decline can be attributed to over-attribution rapid growth populations of poisonous starfish.
Fancy Pillow
As a group, sea stars are named for their star-shaped shape, but some species have a completely different shape. Genetically being true starfish, cushion stars (Culcita novaeguinea) at first glance have nothing in common with the sea star. They are missing arms and their swollen body is more pillow-like. Often covered in tiny vertebrae, these strange animals can reach lengths of over 25 centimeters and come in a wide range of colors. While other starfish may hunt shellfish and open their shells, cushion stars are much gentler creatures with a less dramatic lifestyle. They mainly feed on algae, and sometimes coral. Pillow stars also serve as a home of sorts for other species of marine animals in a strange symbiotic system of relationships. Fish can live in the water-filled cavity of this star, while invertebrates outside clean the prickly vertebrae of the pillow.
Starfish diseases
Recent news of the catastrophic extinction of starfish has brought attention to this issue. A wasting disease of starfish that results in mass extinctions and the final fragmentation of the animal, was potentially classified as a densovirus. This is especially true of the 2014 die-off along the Pacific Northwest Coast. The problem of low population resistance to infections has been discovered, threatening the existence of some types of stars. It turns out that different species of starfish show different levels of disease sensitivity. Scientists are now trying to determine environmental consequences declines in sea star populations and their impact on biodiversity marine environment. They are also trying to figure out what factors environment increase the spread of infection. Potential root causes include environmental pollution.
Starfish Eyes
Due to the lack of blood and a typical central nervous system, it would be natural to assume that starfish also lack eyes. However, starfish do have eyes, and they are located in quite strange place: at the tips of their hands. These eyes collect visual information to guide the starfish in a direction of interest. They are similar in shape and structure to the eyes of arthropods, insects and crustaceans. Another question arises, how can they see without a brain? Recent research has shown how starfish use their eyes to navigate with amazing precision. An investigation by Anders Garm from the University of Copenhagen showed how the blue starfish moves up to a distance of 2 meters towards the reef. Visually detecting the reef as a dim smudge (stars are color blind) they race towards their desired habitat.
Stars can change gender
It often happens that the simpler the animal, the more superpowers it has, such as limb regeneration or the ability to change sex. Certain starfish can change gender and then switch back. The reasons for the change are varied and may include both the need to reproduce and a response to water quality, temperature and food availability. Gender differences in sea stars are quite subtle from an external point of view, although males fewer females. Some varieties have both male and female organs and can take on either role when mating. They carry their young on their backs until they are ready to make their own journey along the ocean floor.