10 amazing facts about starfish Amazing facts about starfish
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 life span 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
I wonder how they breed, how they feed sea stars... 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 skeleton structure - rays depart from the central part. The skeleton of sea beauties is unusual. It is composed of calcite and develops inside a small asterisk 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 are interested in how starfish eat. Briefly about their structure digestive system can be found below. These amazing beauties give the impression of perfect safety. In fact, they marine predators, gluttonous 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 along, but the victim cannot escape. Everything that a starfish eats is easily digested in its stomach.
She acts 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 push the flaps apart.
As soon as at least a small gap appears, the external stomach is immediately pushed into it. Now the sea gourmand 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 adaptations 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 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. For a while 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 try in advance to postpone nutrients for the entire mating time.
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 seawater, 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 caring parents: they carry eggs on their backs, and then larvae. Have certain types For this, during mating, special caviar bags appear on the back, which are well washed with water. There she can be with the parent until the larvae appear.
Reproduction by division
Absolutely extraordinary ability sea stars - 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 ray, 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 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, seafood predominates. large birds... On the shores warm seas they become prey for seagulls. V Pacific 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 that at the same time repels pests. But this method was not widely used either.
Starfish are amazing sea animals that have different colour, shape and size, although they all resemble a star. Some are smooth, some with spines on the upper surface and smooth with back side... If you turn the star upside down, you can see its tubular legs. Find out more about these fascinating animals!
1. Starfish are not fish.
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Although starfish live underwater, they cannot be called fish. They have no gills or fins, and they move in a completely different way. Fish move with the help of their tail, and the stars - with the help of tiny tube legs that help them move along the bottom.
2. Starfish belong to the echinoderm type of marine animals.
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This means that they have something in common with flat sea urchins, common sea urchins and sea cucumbers ( sea cucumber). All echinoderms are star-shaped, that is, their body is divided into five rays located around the center. If you've ever seen a starfish, you know that it has exactly five rays.
3. There are thousands of types of starfish.
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There are about 2000 known species of starfish. They live in intertidal zones or on great depth, in tropical or cold regions.
4. Not all starfish have five rays.
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While the five-rayed starfish are best known, many other species exist. Some of them can have up to 40 rays!
5. Starfish are capable of recovering severed rays.
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If a predator grabs a starfish by the beam, it can throw it off like a lizard's tail and escape from pursuit. Starfish can generate most of their vital organs in rays. Even from a single remaining ray can grow new star... However, this will take time. For example, one ray grows for about a year.
6. Starfish have a protective coating
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Depending on the species, starfish have a rather tough, leathery or needle-like coating consisting of plates of calcium carbonate with tiny spikes on the surface. Starfish use spikes to ward off predators, which can include fish, birds and sea otters.
7. Starfish have no blood.
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Instead of blood, they have water vascular system... The star pumps water into itself through the surface of the skin, and the legs help to distribute it throughout the body.
8. Starfish move with the help of their tubular legs.
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Starfish move along the seabed using hundreds of tubular legs. These legs are located on the bottom of them. The legs are filled with water, which the star absorbs by the surface of the body. A starfish can move much faster than you think. If you find yourself on the seashore at low tide or see a large seawater aquarium, see how these animals move. The tubule legs also help the starfish retain its prey: bivalve molluscs and mussels.
9. Starfish can throw the stomach out
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Starfish hunt very in an unusual way... Their mouth is known to be in the lower torso. They hunt bivalve molluscs and mussels, as well as small fish, snails and barnacles. Starfish wrap their rays around the shells and open them, after which they throw out their stomach through their mouth and immerse it inside the shell. Having captured the victim, the stars set the stomach into place together with the victim. This unique opportunity allows the star to eat well, despite the very small size of the mouth.
There are about 1600 in the world modern species sea stars (lat. Asteroidea) and they are found practically at any depths of the World Ocean.
Starfish are echinoderms that include both invertebrates and vertebrates.
These star-shaped ones have from 5 to 50 arms-rays and usually their number is a multiple of five.
The ancestors of sea stars had six rays, and, according to Dr. Marc de Lussanne of the Institute of Psychology at the University of Münster, their structure was symmetrical. However, their sixth ray disappeared long ago in the process of evolution.
Like most marine life, the stars are brightly and variedly colored, but there are species that merge with the bottom surface.
Starfish range in size from 2 cm to 1 meter, although most will easily fit in an adult's hand.
Stars have gills, which are hollow, thin outgrowths of the body wall that are ventilated sea water outside and coelomic fluid (not blood) from the inside.
Most starfish feed on carrion or are predators that prey on various animals, especially snails, bivalve molluscs, crustaceans, polychaetes, other echinoderms and even fish.
Several soft-bottom starfish, including species from the genera Luidia and Astropecten, are able to locate buried prey and then excavate the substrate to reach it.
Most starfish locate and locate prey from substances released into the water by their prey, and many species that are hunted by starfish have evolved to evolve avoidance responses from slowly moving starfish.
Some starfish are capable of turning their stomach inside out through their mouth. The star envelops the prey with its stomach, which it cannot swallow, and thus carries out external digestion. If their prey is protected by a shell, such as a mollusk, a gap of only 0.1 mm is enough for the predator to squeeze through its stomach and release a digestive enzyme that softens the muscles holding the shell valves. Japanese species Astreias take from 2.5 to 8 hours, depending on the type of clam, to digest the whole prey.
A small number of starfish species feed on plankton suspended in the water column (Echinaster, Henricia, Porania), while others consume deposited material (Ctenodiscus, Goniaster) in contact with the body surface. This material is captured by the mucus and then transported by the cilia of the epidermis towards the oral surface.
The stomach, which turns inside out, is an efficient food organ for many omnivorous and non-predatory starfish. The starfish Patiria miniata from the west coast of America spreads its stomach along the bottom, digesting organic matter... Likewise, the tropical pillow star Culcita and Oreaster, which inhabit Coral reefs, feed on sponges, algal felts and organic films.
The body cavity is filled with a coelomic fluid containing numerous amoeboid cells. These cells absorb waste products and foreign bodies and leave the body through the integument. Thus, they perform excretory and immune functions.
In starfish, the eyes are located at the ends of the rays.
The movement of blood in Asteroidea occurs due to muscle contraction. The study of blood circulation in sea cucumbers demonstrates that the blood flow through the vessels periodically increases and decreases (which indicates the presence of a rhythm similar to that of the heart). At 25 ° C, Asterias forbesi's heart beats approximately 6 times per minute.
The body fluids of all starfish, as well as those of all echinoderms, are close in composition to sea water... Their inability to regulate salt prevents the majority of species from living in river estuaries and in fresh waters.
Lavender starfish. This absolutely incredible starfish is native to the reefs of Bunaken Island in Sulawesi, Indonesia.
Deltoid starfish between emerald corals in the western Pacific Ocean.
Starfish devour oysters, causing economic damage to fisheries. From time to time, starfish have to be removed from commercial oyster cans with a tool that resembles a wide mop that drags along the bottom. Starfish get entangled or grab the threads of the "mop" with their pedicellaria, they are lifted to the surface and destroyed.
For some starfish, reproduction by splitting is normal. asexual reproduction... In this case, in the plane of division, the softening of the connective tissue occurs. The most common form of fission is to halve a star. Each half then regenerates the missing parts of the disc and arms, although extra arms often appear along the way.
Damaged starfish regenerate very easily, completing lost arms and damaged parts of the disk. The completion of regeneration is slow and sometimes takes a whole year to complete.
The species of the Linckia genus of starfish, common in the Pacific Ocean and other regions of the World Ocean, are unique in their ability to throw off their hands entirely. Each individual hand, if not eaten by a predator, can regenerate a new body.
The rays (hands) contain the digestive outgrowths of the stomach and the outgrowths of the genital organs; inside the arms is located along the longitudinal row of vertebrae.
The legs of starfish are flexible tubular outgrowths, usually with suction cups at the end, and are activated by water pressure in the internal canals and ampullae of the ambulacral system.
The tropical Pacific star Acanthaser planci ("") is known for its rate of consumption coral polyps... Due to their high density (about 15 adults per 1 m2), these stars have already been destroyed by now. a large number of reef corals in some areas.
Amazing miracle of nature, living at the bottom of oceans and seas, absolutely different colors... Starfish are the creation of insane beauty. They are rarely seen with our own eyes, and only television screens are ready to reveal to us the secrets of these creatures.
We will allow ourselves to slightly open the curtain into the depths of salt waters and tell Interesting Facts about starfish
1. The most unusual thing about these animals is that they cannot swim. They move in the water with the help of their arms and legs, which have suction cups. So they cling to the bottom and move along it.
2. In total, sea stars have five "paws" in their arsenal, which they use during life. However, there are also non-standard "whopper", for which this number is 10 times higher. There are very few of them and you will hardly find them in the waters of the ocean.
3. The diet of stars consists of oysters, crayfish and shellfish. However, by eating them, the process of digesting food takes place outside the body. The stomach, which has two lobes, "exits" through oral cavity for this. And, until the moment when everything is ready, he does not return to the inside of the body of the starfish.
4. Rainbow creatures are also "equipped" with a heart. It beats very slowly, about 7 beats per minute.
5. The body of starfish is covered with thorns and thorns. This is a kind of their "defense" in case someone wants to attack them.
6. Did you know that these "stars" have no head or blood? They do not have a central brain, blood also does not "please" these creatures.
Only the vascular system is inherent in them. But it is then fully developed.
7. The term that these creatures can live under water is about 35 years. And, it's worth noting, the conditions can be completely different. So, for a longer life, starfish choose colder waters for their homes, even, one might say, icy ones.
8. Do you know when sea stars were first born? It happened about 450 million years ago!
Amazing creatures of nature can also throw off their limbs - "rays" in case of danger. They can return back, and if not, this is not a problem, from one such "ray" a full-fledged star will soon reappear.
Other interesting facts about starfish can be found on the Internet.
