Sharks eat dolphins
Sharks are fish from the class of cartilaginous fish and thus belong to the vertebrate group. As the name suggests, they don't have bones, they have cartilage. This is supportive tissue that does not contain nerves or blood vessels. In the cartilaginous fish, a special type of lime accumulates there and gives the tissue strength. Sharks move by moving their caudal fin sideways back and forth. Sharks breathe through their gills. The life expectancy of a shark is between 20 and 50 years. There are around 500 different species of shark around the world. Sharks can be found in the sea / ocean (salt water) as well as in fresh water. The whale shark is the largest species of shark, it mainly eats plankton, which it filters with its big mouth, it is the only shark that has no teeth. The great white shark is the best known species of shark and, from our point of view, the most "dangerous" species. The shark is not an extremely stupid and aggressive animal as many people think. In truth, sharks are very intelligent and curious animals. Sharks learn through observation and exploration. Sharks are very frugal. They only eat every few days and do not need a lot of food. A fully grown blue shark, for example, eats around 100 kilograms in a whole year. Sharks have to live in the water or they will suffocate. You breathe through your gills rather than your lungs. These are long, narrow openings on the side of the head. Sharks use it to filter the oxygen out of the water.
The life of the sharks Edit source]
Way of life[Edit | Edit source]
"rest" at the bottom.
nutrition[Edit | Edit source]
All sharks belong to the group of carnivores, i.e. carnivores. Most species feed on fish, crustaceans, molluscs, and seals. Some sharks also eat seabirds, dolphins or their own conspecifics. The largest sharks such as the basking mouth shark (Megachasma pelagios) and the whale shark (Rhincodon typus) feed exclusively on animal plankton. Humans are definitely not part of the shark prey scheme. Especially old, weak or sick animals are preferred by Haken. Sharks do not indiscriminately devour prey. Once a shark has discovered an animal that resembles its preferred prey, it first takes a so-called test bite. The shark uses its very well developed sense of taste to decide whether the prey is edible. The test bite also serves to weaken the prey, especially in the case of great white sharks.
Reproduction[Edit | Edit source]
Little is known about the reproduction of sharks. Sharks become sexually mature and relatively late
produce few offspring. The low reproduction rate in connection with the hunting of the animals leads to a sharp decline in many shark populations. In all species there is internal fertilization of the females by the males. A large number of sharks give birth to live young that hatch out of their egg shells in the female (ovoviviparous). The gestation period is between six months and almost two years, depending on the species. In other species, the young mature in the uterus and are also born alive (viviparous). About 30 percent of sharks lay eggs (oviparous). For this purpose, the females usually anchor a few, stable egg shells on plants or other objects to prevent them from being washed away.
Solitary fishermen and schooling fish [edit | Edit source]
There are many sharks that live as solitary animals and only come together with other conspecifics during the mating season. But that does not apply to all, there are also sharks that live together in groups (schools), these sharks are called schooling fish, including the hammerhead shark, which occurs both as a loner and as a schooling fish. Often, sharks only come together as a large group during the mating season in order to look for a partner there. For example, the more dominant sharks push their same-sex conspecifics to the edge of the group so that they do not get a partner. Little is known about shark family life. For example, there are also sharks that hunt in groups. One thing is certain: Sharks are very social and also live in schools, not just as loners. Because by no means all sharks are loners.
Why do small fish always swim with sharks? Edit source]
These fish are called "ship keepers". They are a family of perch-like. They are slender fish that, with the help of a suction plate that has formed from the first dorsal fin, attach themselves to larger fish e.g. B. attach sharks or marine mammals to be taken away; they also occasionally try to attach themselves to divers. This gives ship owners the opportunity to take part in the host animal's meals. In addition, they enjoy the protection of the larger animal from other predators and probably rid their host animal of parasites.
The shark - the prehistoric animal [edit | Edit source]Sharks existed on this earth long before the dinosaurs.
The ancestors of today's sharks lived on earth around 300 million years ago. One of these primeval sharks is e.g. the already extinct megalodon. Today's sharks have been around for around 50 million years and hardly differ from their ancestors. They haven't changed much in all these years. Sharks are one of the oldest living animals in the world. Since the shark has been on earth much longer than humans, most sharks have never seen a human and therefore do not even know what a human is.
The shark and the ecosystem Edit source]
Sharks play a special role in the marine ecosystem. They are at the top of the food chain almost everywhere in the ocean. In doing so, they keep the populations of other fish stocks healthy and in balance with their environment. But how do sharks maintain ocean health?
Very few people know what vital role the shark actually has in the marine ecosystem. Sharks are the "regulators" in the sea. Sharks have been at the top of the food pyramid for over 400 million years. Depending on the species, they eat sick animals or smaller predatory fish and thus ensure a functioning ecology in the sea. Sharks are so-called cartilaginous fish. They reproduce very slowly. About 20% of the sharks lay eggs, 80% give birth while alive. Sharks only have between 2 and 100 young. No comparison to the millions of eggs of the "bony fish". If the shark population is reduced even further, there is hardly any possibility of redressing this imbalance. As a result, the sharks will no longer be able to keep the ecosystem stable and in balance. Scientific studies show that a coral reef that kills all sharks dies within a year. Many marine zones are already considered ecologically dead areas. In view of the current oil spill in the US, more areas will be added. While all these things happen in secret, under water, a rethinking process must finally take place in public. Something must visibly happen! Because it is - as in many other areas of life - a second before twelve. And despite all the warnings, the killing of the sharks continues unhindered.
Keep food webs in balance[Edit | Edit source]
Sharks have developed a close, interdependent relationship with their environment. Your eating habits
correspond to efficient strategies - by hunting down old, sick and slower fish, they help keep their prey populations healthy. Sharks thus ensure that the populations of many sea creatures remain in natural equilibrium and that there is no excessive increase, which in turn would damage the ecosystem. The marine ecosystem is made up of complex food webs. Sharks are at the forefront of these food webs and are considered a "key species" by scientists. This means that their disappearance leads to above-average changes for other species populations and processes in the ecosystem and thus leads to the collapse of the entire structure. A series of scientific studies shows that the sharp reduction in the number of sharks also leads to a reduction in commercially relevant fish species. This occurs along the entire food chain and also includes the tuna sector, which is important for the fishing industry, as well as other species that are important for the preservation of coral reefs.
Sharks keep prey populations healthy[Edit | Edit source]
The predatory sharks prey on sick and weak animals, while others even search the ocean floor for carcasses for food. In doing so, they prevent the outbreak and spread of diseases that can have devastating consequences. Hunting the weakest prey also strengthens their gene pool. As a result, only the largest, strongest and healthiest fish reproduce. The result: more healthy fish.
Influence sharks[Edit | Edit source]
Sharks use intimidation to determine the behavior of their prey and thus prevent overgrazing of essential habitats. In addition, the animals developed new skills to escape enemies, and that by influencing the shark. Sharks have had a major impact on other sea creatures over the years that they have been around. All animals had to adapt to him, whoever was too weak was exterminated, but whoever developed further remained. Some shark researchers even believe that this “intimidation factor” has an even bigger impact on the marine ecosystem than what the sharks actually eat. For example, shark researchers in Hawaii have found that tiger sharks have a positive effect on keeping seagrass fields healthy. Turtles, which are part of the prey of the tiger sharks, graze on such seagrass meadows. Due to the lack of tiger sharks, the turtles spent all of their time eating the best and most nutritious seaweed, so that this habitat was soon destroyed. However, when tiger sharks were there, the turtles grazed in more extensive areas and did not overgraze a specific region.
Sharks provide oxygen[Edit | Edit source]
The rainforests of our earth play an important role in relation to our world climate. What many people do not know, however, is that two out of three breaths of oxygen that we humans take are produced in the ocean. Above all, phytoplankton, which makes up the largest part of the earth's biomass, produce the oxygen that is so important to us. The collapse of the food chain, i.e. the disappearance of an important link in the food chain, such as a shark, would lead to a reduction in phytoplankton. As a result, this would result in a reduction in the oxygen content, which in turn has a strong impact on humans and all other organisms that rely on oxygen. Almost 70% of the earth's oxygen is produced in the oceans. Be it the Gulf Stream, the direct influence of the sea on coastal areas, the regulation of the global climate - the oceans are the control centers of the earth's ecosystem. If the marine ecosystem collapses, the earth will become uninhabitable within a very short time ... All natural processes are based on a deeper wisdom that we humans apparently lack. The (thorn) crown of creation can be described as the stupidest of all creatures in every respect, since no other living being has successively its own
Livelihoods destroyed. The creatures of nature, and especially the creatures of the sea - in which all earthly life began - are no coincidental products. Each has its function and has emerged from natural wisdom. Wherever we thoughtlessly intervene, we change something, thereby disrupting the natural balance. The self-healing power of Mother Nature, however, is so great that we would only have to keep our hands off her for a while so that she can regenerate. But we don't do that. On the contrary! We continue to inflict wound after wound against her better knowledge. So we will have to experience the consequences of our actions. In any case, there will be “natural” consequences, because nature will, in the long run, bring the “unnatural” that we add to it back into a natural order. Nothing can oppose this, especially not humans. If we go along with this transformation process and transform ourselves back into natural beings, there is hope that the human species will not go down in cosmic history as a failed experiment by Mother Nature.
The extermination of the top predator affects the entire food chain[Edit | Edit source]
A cut off shark fin. The rest of the shark is thrown back into the sea, where it dies in agony. A scientific study 1 in which the fish stocks on the Atlantic coast of the USA were examined found that 11 species of shark have already been almost extinct. As a result, 12 of the 14 species populations that belong to the prey spectrum of the sharks have increased sharply and thus have caused great damage to the ecosystem. For example, the number of cow-nosed rays in the waters has grown in an uncontrolled manner. Since shellfish such as oysters and scallops belong to the preferred diet of the rays, their stocks were practically completely destroyed. (Please click to start the slide show) But people like mussels too! The mussel fishery, which has flourished well for over 100 years, sank to 13% 2 and thus almost completely collapsed. This means that there were no more mussels that could filter and purify the sea water.
Consequences of the shark hunt[Edit | Edit source]
As top predators, sharks play an essential role in the marine ecosystem. An extinction of the sharks would lead to a big change in the sea. The severe overfishing of some shark populations has
It has already been shown in some areas that the local food web was severely disrupted as a result. In a study conducted by Dalhousie University in 2007, it found that the unusual decline in mussel catches on the east coast of the USA is related to the dramatic decline in the large shark species there . Rays are on the menu of the severely decimated shark species, here in particular the cow-nosed rays and other smaller shark species, which in turn feed on mussels and crabs. Without predators, these rays and small sharks could now reproduce unhindered and the onslaught on existing mussel populations was correspondingly large. While the cow-nosed rays used to travel in groups of 400 to 800 animals, there are now schools of up to over a million animals. This
affects mussel populations like a locust plague on a vegetation zone. Of the 13 mussel hunters examined, twelve benefited from the absence of the large predators. It is obvious that the water quality of these marine areas suffers without the filter feeders and detritivores, with all its consequences. In a 2005 study, a Mexican / US research team showed that a coral reef, where all sharks are killed, will die ecologically in just one year, a terrible idea, but one that is already becoming a reality. In many marine zones there are already ecologically dead or changed areas, partly because the sharks have been overfished there. Unfortunately, little of this has been exposed to the public, as the great white shark has been heavily hunted for decades in South Australia. As a result, the seals living there multiplied so much that they now have to be regularly decimated by humans. The seal colonies eventually got so big that there simply wasn't enough food for everyone. This effect runs through all levels, excessive growth and at the same time excessive consumption ultimately lead to breakdown.
Summary[Edit | Edit source]
Where sharks disappear, the marine ecosystem becomes unbalanced. In areas where there are no longer any sharks, one can see the dire and dangerous consequences of what happens when top hunters disappear from a food web. This is an important lesson! Sharks are killed for shark fin soup for their fins. A dish that may have a cultural value but is insignificant to human survival or health. The extinction of sharks, however, results in the loss of important food sources on which our survival depends. Although sharks survived for more than 450 million years, they will be extinct within the next 10 years. They have shaped life in the oceans, which cover two thirds of the earth, for 450 million years and are crucial for the health of our planet and ultimately for the survival of humanity. With the increasing demand for shark fin soup, the gruesome slaughter of sharks has increased to such an extent that many species of shark are on the verge of extinction. What happens to the health of the oceans when such an important and significant species as sharks no longer exists? Do we want to leave the destruction of the sharks and with it the destruction of the seas to our children as an inheritance?
Perfect hunters Edit source]
Sharks have a streamlined body that allows them to emerge from nowhere like Tobedos at high speed. The two pectoral fins generate lift and serve as elevators, the dorsal fin secures the body like a ship's keel from tilting. Sharks are therefore perfectly adapted to the conditions in the sea and therefore they are very fast and nimble hunters. Due to their proportions, they can easily turn around to change direction. In addition, sharks can increase their speed in a flash. The slim physique of the sharks is ideal for quick swimming. The mako shark is the sprinter among sharks. It whizzes through the water at speeds of up to 70 h / km. The front part of the body is flat so it can turn faster. The caudal fin is vertical and very mobile, it gives the shark drive. He steers with his pectoral fins. The dorsal fin ensures that the shark does not tip over. Their skin also helps the sharks swim. It's covered with tiny teeth, like tiny thorns bent backwards. The water flows through them as if through a canal. And the water loses its braking effect.
Teeth without end Edit source]
Sharks have their mouths on the underside of their heads. Actually, therefore, they should push their prey away with their long noses. But her jaw is only loosely attached to the skull. If the shark wants to bite, it opens its mouth wide. The movable snout is directed upwards. Then the upper jaw pushes forward and all the teeth dig into the prey. When the prey is shaken around, the teeth act like a saw so the shark can tear out pieces of meat. Teeth can get stuck or get lost, but that doesn't matter, because sharks get new teeth all the time, they have several rows of them. If a tooth falls out, a new tooth moves out of the tooth formation pit. This is called a revolver bite. A shark can acquire thousands of teeth in the course of its life.
With a few exceptions, all sharks are able to tear their prey into bite-sized pieces or to devour it whole. Since sharks cannot chew, they have an extremely powerful and robust digestive system to compensate for this: the digestive juices of most shark species are extremely acidic and can even dissolve bones. The sharks' main weapons are their sharp teeth. In contrast to other vertebrates, which have to make do with one or two sentences for life, the teeth of the shark constantly grow back and replace the used ones. Over time, the older teeth migrate to the front of the jaw until they finally fall out or get stuck in the prey. The new teeth are then immediately available behind the old ones. Behind each row of teeth, several new rows of teeth grow in a tooth formation pit. If a tooth falls out or breaks off, the new tooth folds out of the jaw from the back to the front. Zack - the gap is filled. On average, a shark loses around 20,000 teeth in its lifetime. Depending on the type of shark, there are several or only one row of teeth. The tiger shark has only one, but the dogfish three.A tiger shark needs around 1,400 teeth in ten years. And young lemon sharks change their front row of teeth every week. Imagine that: every week
new teeth! It is assumed that sharks change their teeth about every 8-15 days, although this is different for each species of shark. In addition, younger sharks usually lose significantly more teeth than older sharks. When you consider how many teeth a shark will use in its lifetime, this is hardly a surprise. Shark teeth are arranged in rows, the number of which varies depending on the species. The front row is always in use (although some species use up to eight rows at the same time), these are the largest teeth in the shark's mouth. The second row of teeth is smaller than the first, the third smaller than the second, and so on. Every time the shark loses a tooth, the tooth moves forward from the next row, replacing the lost one. This is possible because the teeth of sharks are not anchored in the jaw, but attached to the skin that covers it. New teeth are constantly being formed in a corresponding recess in the shark's mouth and the skin acts as a “conveyor belt” on which they advance one position at a time. Their special teeth have enabled the sharks to develop very strong jaws: without the ability to replace lost teeth quickly, they could never have developed such a great biting force, as the regular loss of large numbers of teeth when hunting is a benefit better shooting of the prey could not have been made up for by the enormous power of their jaws. The time that a tooth is used varies depending on its age and species: Younger sharks lose teeth more often. There is also evidence that some species of shark have teeth that last longer during periods when the water is colder and the animals are eating less anyway. While individual teeth are replaced in most species of shark, there are also species such as the cigar shark that change the entire set of teeth at the same time. The total number of teeth a shark will use in its lifetime can be huge, reaching up to 30,000 in some species! That's about 937 times what people usually have! While shark teeth share the same characteristics as described above, there are huge differences in their shape and function. Since there are four basic feeding patterns in sharks, four basic tooth shapes also exist. Fish-eating sharks have long, pointed, needle-shaped teeth that are ideal for holding onto something as slippery and streamlined as a fish. Sharks that seek their prey on the ground and feed on mussels and crustaceans have thick, plate-shaped teeth that allow them to perfectly crack the shells of their prey. Tiger sharks, great white sharks, and other species that primarily hunt seals and other mammals have sharp, serrated, cutting teeth to help them bite off pieces of meat. Finally, there are the gentle giants among sharks, basking sharks and whale sharks, which feed on krill and other plankton. They do not have teeth as these species get their food by filtering large amounts of water through their gills.
Sharp senses Edit source]
In addition to sharp teeth, strength and speed, the sharks are also characterized as hunters by their extremely well-developed senses. So they have excellent hearing that reacts to sound waves. They have so-called olfactory pits on the underside of their head. They also have an excellent sense of smell. Sharks can smell an injured animal if it has lost just a few drops of blood in the sea. In addition there is the electrical instinct. Sharks thus perceive even the weakest electrical currents that arise even with the slightest movement. The organ with which the shark recognizes these currents are so-called "Laurenzinian ampoules". They are made up of tons of tiny openings in the skin around the snout. These pores report the electrical voltage to the nervous system. This means that the shark knows where its prey is. In the end, the shark also sees its prey.
Sharks have an excellent sense of smell. Thanks to this good sense of smell, the shark can smell blood from 500 meters away, for example, even if it is very dilute. They can also distinguish blood from one another by smell and taste. Even better than the sense of smell is the shark's hearing. Which means they can find their prey from a distance. Because with their good ears, sharks can pick up the low-frequency sound waves that come from injured fish more than 2 kilometers away. In addition, sharks have lateral line organs to locate animals. These lateral line organs respond to changes in water pressure caused by an animal over 200 m away.
The eyes of sharks are ten times more sensitive to light than those of humans, so sharks can clearly see their surroundings even in relatively deep and murky water. When attacking, many sharks - e.g. the great white shark - roll their eyes into their skulls so as not to injure them. Some sharks also have some kind of extra eyelid (the nictitating membrane), which also serves to protect the eyeball. The shark's eye has no eyelid but no real eyelid. That's why it looks so rigid, because a shark doesn't blink. The shark doesn't need to darken its eye underwater. However, some species of shark have what is known as a nictitating membrane. This fine membrane can be pushed over the eye and comes from the eyelid. With this skin, the shark protects its eye from foreign objects from entering, but it does not close it to sleep.
Sharks have small, gelatinous channels on their heads that penetrate deep into the skin and end at nerve cells. Thanks to these highly sensitive electrorceptors, the Lorenzini ampoules, they can even register very weak electrical fields and impulses. This allows them to pinpoint their prey, even if they cannot see. The prey's smallest muscle movements generate weak electrical impulses that a shark can detect nearby, even if the prey fish remains motionless on the sea floor in complete darkness - its heartbeat gives it away.
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