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The Roman Empire The Roman Empire / Римская империя The Roman Empire had a huge task in front of them while it was first starting out and while it was becoming a dominant dynasty in the early civilizations. The main problem that the book "Discovering the Global Past" points out is how the Roman Empire found itself growing a little too quickly. The Roman Empire started out very small...

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U.S. Financial System U.S. Financial System / Финансовая система США Corporations have the need to raise capital for a number of reasons. Smaller firms need capital to start up operations. Larger firms need capital to expand operations and to finance inventory. There are various ways in which a firm can raise capital through the financial system and numerous individuals and entities...

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Microburst Microburst / Микропорыв There are many safety factors that pilots have to take into consideration while completing a safe flight. Everything has to be taken into mind when planning a flight. From weight and balance to preflight inspections. One safety factor that is impossible to have control over is weather. There are many aspects of weather that can affect an aircraft,...

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Romanian Orphanages Romanian Orphanages / Румынские сироты Imagine a hospital that, at one time ran smoothly helping the public, now with the primary objection of taking care of the thousands of abandoned infants and children. This is the reality in Romania when Nicolae Ceausescu was in power. In 1966 he created an Anti-Abortion/Contraception law in order to raise the population and...

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Introducing Christian Ethics Introducing Christian Ethics / Введение в христианскую этику The book that I have chosen to do my book review on is Introducing Christian Ethics, written by Henlee H. Barnette. This book deals with many Christian ethical decisions based on biblical foundations that are applied to various major problems. Some of the major problems pertain to the self,...

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Dolphins

Топик на английском по теме: Science / Наука

Dolphins

Dolphins / Дельфины

«No arguments can rationalize the forced confinement of these social and highly intelligent creatures», said Richard O’Barry1. He is very right. Dolphins are one of the most social and intelligent creatures in the world. Some people think that they may be smarter then even chimpanzees. Their intelligence has been tested many times over and they have been found to be able to do arithmetic and memory games. Dolphins are very socially sophisticated creatures. They have a complex language, which is in areas comparable to the language of humans. They have the ability of echolocation, which has many uses. Their ability to use echolocation has even helped humans, mainly in the military. Finally dolphins are very social animals. They have complex social grouping and have many emotions.

«Cetaceans (dolphins) communicate over hundreds of miles, making theirs a truly global society. Surrounded by this universal conductor of communication, marine mammals develop unusually strong bonds to one another. Individuals depend heavily on their position within the group, or «pod,» for their identity?» says Jean-Michel Cousteau abut dolphins and their communication. Dolphins communicate using an extensive system of whistles, which are similar to human voices. (Jean-Jean-Michel, 2000)

«Each herd of dolphins has its own sound signature»(Au, 1993) this allows the dolphins to tell each other. The unique whistle of each herd is called its «coda». An example of how dolphins use these «coda» is when they dive for food. When they dive as a group, they often fan out in search of food. When they are done, they congregate using their clicking sounds. Dolphins can also use their whistling to manipulate situations. It seems as if though dolphins have problem solving skills. French aquanaut and Film-maker Jacques-Yves Cousteau and his crew trailed a heard of dolphins. The herd seemed to be comprised of a few males and one male. As they approached the herd, they heard many soft clicks. As they got closer, everything changed. «They heard a very loud burst of clicks from the large male. The rest of the group fell silent. The male sidled up to Cousteau’s ship and spouted for all he was worth. He seemed to be deliberately making himself conspicuous, drawing the researchers away. Meanwhile, the female dolphins exited in the opposite direction.»(Bright, 1997) The male dolphin then continued on to dash away from the researchers and rejoins his herd. The dolphin male had sensed danger and had communicated with the rest of his herd what he was about to do. They solved this problem using different frequencies of whistling.

«Echolocation — the location of objects by their echoes — is a highly specialized faculty that enables dolphins to explore their environment and search out their prey in a watery world where sight is often of little use. As sound travels four and a half times faster in water than in air, the dolphin’s brain must be extremely well adapted in order to make a rapid analysis of the complicated information provided by the echoes.»(Hillix, 2003) As said in the book, dolphins are able to do many things simply by using their ability of echolocation. It helps them navigate, hunt, and even kill their prey.

The dolphin is able to generate sound in the form of clicks. The frequency of this click is higher than that of the sounds used for communication and differs between species. When the sound strikes an object, some of the energy of the sound wave is reflected back towards the dolphin. As soon as an echo is received, the dolphin generates another click. «The time lapse between click and echo enables the dolphin to evaluate the distance between it and the object; the varying strength of the signal as it is received on the two sides of the dolphin’s head enable it to evaluate direction.» (Au, 1993) By continuously emitting clicks and receiving echoes in these ways, the dolphin can track objects and home in on them. Echolocation is how dolphins navigate. They «see» distant underwater terrain using sound as clearly as we see the above water terrain using our eyes. Their complex sonar can tell the shape, speed, and density of the object that they are racing towards. This allows them to navigate, because they are able to detect when they might hit a large object or they may have it in their memory of where they are. Dolphin’s echolocation also has the ability to kill or stun their prey. «?that dolphins close to herring would emit low bangs at the frequency the fish hear best at, and had suggested the bangs were designed to damage the fish’s hearing apparatus. He has now taped a dolphin emitting a sequence of low- frequency «bangs» while chasing a fish.»(ABC.net, 2001) In this case, it was shown that dolphins had used their sonar ability, or echolocation, to stun a fish. The dolphins recognize the frequency at which the fish hear at, and give a low bang towards the fish. This stuns the fish, and aids with the dolphins hunting. Other evidence states that dolphins may even be able to kill their prey with these bangs of sound. «She recorded wild Atlantic spotted dolphins emitting a medium-frequency buzz while searching for prey in sand on the seabed. She says buried eels jumped out of the sand, and either stopped completely or moved sluggishly as if they were stunned, giving the dolphin time to catch them.»(ABC.net, 2001) In this case, the dolphins used their sonar to detect their prey and then stun or kill it at the same time. The eels were shocked out of their hiding, where the shock of being disturbed by the buzz stunned them or in some cases killed them. This is extremely Beneficial to dolphins, for it will make their hunting much easier.

Finally, dolphins are extremely social. «Dolphins are highly social animals and live in family groups called pods, the social organizations of pods can be very complex, it varies between species and even within species living in different parts of the world, however for a very general overview all species are two types of pod.»(Galia, 2004) The first is a ?natal’ pod, this consists almost entirely of females and their young (calves) and can be either matriarchal (highest ranking dolphin is female) or patriarchal (highest ranking dolphin is male). «In a patriarchal pod there is a principle male who controls the primary mating rights to the females of the pod, when a female is approaching season the principal male will become more territorial and chase away other males.» (Galia, 2004) In some cases there can be a pseudo-alliance between males in a patriarchal pod, 2-3 males might be responsible for primary mating in a pod, effectively sharing the top rank. A matriarchal pod is one in which the females choose which males mate with them. «Conflicts over mating rights are common in both matriarchal and patriarchal systems.» (Galia, 2004)

«The second type of pod is andadolescent’ pod. This is made up of young males who have left or been forced from their natal pods after reaching a certain age, these young males join together and form their own pod while they look for a new natal pod.» (Galia, 2004) Individuals in adolescent pods live in the same way as they do in natal pods, there is a hierarchy and the dolphins often hunt together, an adolescent pod will consist of dolphins from one particular natal pod, this is not surprising as most dolphins breed seasonally (or at the least breed all year round but with peaks at certain times of year) because of this a number of dolphins may reach sexual maturity at the same time. «Pod sizes can vary from at few as 2 to as many as 200, although very large pods are subdivided into smaller sub-pods.» (Galia,2004)

«Dolphins can get angry, normally this happens as males compete for mating rights, however they rarely show prolonged aggression towards each other, normally the dispute is settled with a few rostrum bumps a couple of nips.»(Bright, 1997) Dolphins can show anger and aggression in several ways; pointing an open mouth at another dolphin is seen as a threat, as is nodding and thrashing or churning of the tail (flipper) is a sign of irritation. Dolphins normally have ‘sonic manners’ and avoid firing strong bursts of sonar at each other, however some researches believe these manners are ignored during and fighting, with the dolphins actively sweeping each other with powerful beams of sonar. «Dolphins also love to play. They are very fun loving creatures.»(Hillix, 2003) Play takes up a large amount of any dolphins’ time, it is an important part of forming and reinforcing the social bonds within a pod, although young dolphins play more than the rest of the pod, when their mothers allow them that it is. Young dolphins sometimes break the ?rules’ laid down by their mothers, seemingly for the fun of it. «Dolphins play all sorts of games, for instance: racing or chasing each other, jumping over one another or mating games.»(Bright, 1997) Dolphins in the wild are often seen riding ocean swells and they seem to love being pulled along by these powerful surges, this behavior is effectively the same as when dolphins bow-ride at the front of moving ships.

«Today, after more than three decades of experience with marine mammals in captivity, we DO know better. Yet we continue to catch them, confine them, and display them for profit.» — Jean-Michel Cousteau. Jean-Michel Cousteau is correct. Humans have learned many things about dolphins. We have learned dolphins are extremely intelligent. They have created their own language and tell different pods apart by the different frequency that the particular pod has. We have learned that they echolocate and that it helps them in many situations. It allows them to navigate in perilous waters, find food, and even allows them to stun or kill their prey. Finally, we have learned that dolphins are extremely social and can experience many emotions.



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