by Ulrich Reinartz
Copyright   © 1998-2008

Tursiops truncatus is the scientific name for the wellknown "Bottlenose Dolphin". In many films we have seen the species as hard working actors.  When the last "Flipper"(who was a lady) died in the arms of her trainer Ric O´Barry, Ric changed his mind and decided to go for the release of captive dolphins who live like prisoners in the dolphinaria or in military institutes, where they have been trained also for offense activities. The release program is not easy to do. First one needs and good place with contact to the open sea, then the money to transport, feed and "train back" the dolphins. They really have to learn again how to use their SONAR system to echolocate living and moving fish. Their skin has to get used to the direct sunlight when the dolphin has been "existing" in environments of artificial light.

It may take one year or more to bring a "flipper" back to the ocean.  Some non-profit  organisations such as the "ARION DOLPHIN PROJECT" located in Berlin support Rics projects and others which go in the same direction.  Also very important is the information work in the cities, where the people go to dolphinaria to see the Entertainer - Dolphin. Some say, that way people learn more about dolphins and the nature. On the other hand, fishermen look for new  jobs because of the overfishing of wide areas of the oceans. People should have the chance to meet dolphins in a nice and respectful way. Their behaviour in the wild is not comparable with the way they act in captivity. Careful and controlled Whale watching may be one possibility to give jobs to the fishermen and authentic information for interested people.

The one who  really loves mother nature will not have fun in the Zoo or in Sea Parks.  The legendary smile of a dolphin is not always a sign for joy and happiness.  In their little pool they cannot dive as deep as they want, they can´t swim over long distances and the might feel like a human who was put in a telephone cabin with mirrors on the walls inside. The acoustic reflections of the pool walls disturbs the perception by echolocation, which could be described as: Dolphins see with their ears ! The dolphin sonar is a high developed instrument for localization and discrimination of objects in underwater environments, where the visual sense is limited by plankton and the absorption of light. They can detect signals of very low intensity, such as complex echos reflected by objects, in noisy environments. The directional detection capabilities of dolphins are perfectly adapted to the water. The use of sound in a frequency range of 300-180.000 Hz  and the discrimination of some other sound parameters like phase differences or doppler effects allows the dolphin a high resoluted perception of acoustical waves.



Lecture about Dolphins

by Ulrich Reinartz
© 1998

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History   Evolution   Systematics    Brain    Language    Communication-Channels    Soundperception      Soundproduction    Interspecies-Communication    Literature  

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BACK TO INDEX   Today, you see dolphins in commercials for airlines, for cosmetics, and for insurance companies. "Dinosaur-fever" is over; the dolphin wave is coming in. Why are humans so fascinated by these mysterious creatures? The earliest signs of contact between humans and dolphins are the drawings in Stone Age caves in Norway and in South Africa. Romans, Polynesians and Americans write about the mysterious rescue of victims of ship accidents. The ancient Greek culture was also very interested in dolphins; poets described these marine mammals as smooth and gentle creatures. Aristotle studied dolphins because he was a biologist as well as a philosopher, and he thought that dolphins were interested in getting closer to humans.

An Australian tribe included the following in their version of the creation of the earth: " ... (the dolphins) never forgot that all these "two-legged" humans on land are their cousins. And that's why nowadays the dolphins come to find their human relatives, to play with them as they did in the days of the dreamtime." There are many good examples of voluntary cooperation between humans and dolphins. From Brasil, Australia, West Africa and France there are stories of how dolphins work together and cooperate with fishermen. In his book "Dolphin Dreamtime", Jim Nollman describes an old Australian Aborigine who talks about his childhood:

"As a little boy, I often went fishing with my uncle. He studied dolphins for many years. When he called, three dolphins would usually come to the side of the boat and one to the aft. My uncle knew lots of different sounds and could imitate the dolphins. Sometimes he took a little water into his hands and then clapped in a special way. That's how he told the dolphins what kind of fish he wanted to hunt."

The natural curiosity of the dolphins as well as their extraordinary versatility and ability to learn gave some people the idea using these living submarines with their built-in high-tech ultrasound navigation system for military purposes. Dolphins are able to localize small objects and differentiate various materials by ultrasound analysis. They have been trained to transport military hardware under water. Dolphin shows all over the world try to make us believe that dolphins feel fine in prison. But dolphins in captivity die earlier and the birthrate is low. And you get a completely different point of view when you see dolphins out there in the blue. Their joy of living and their intelligent behaviour in fishing or playing is the reason why more and more people want to come closer to them and to know more about these creatures.  So what makes the difference between dolphins and other mammals?

BACK TO INDEX   Over a couple of million years of evolution, the whales and dolphins have developed a brain which is unique in their medium of water. The ancestor of the dolphins went back into the water about 60 million years ago. As soon as they got used to the new medium of water, their brain mass rapidly increased. The design of their brain, the specified zones, and the system of the neocoretex is very similar to the human brain. That can make one wonder, because the two most complicated brains in our biosphere have been generated in total isolation: one on land and one on water - two completely different ways of evolution. Neurophysiologists think that universal laws of nature must exist to explain such a complicated but similar organisation of cells. Dolphins are part of the cetaceans. Their evolution is not clear in all details. A large number of missing links need to be found. The land-based ancestors of the whales are called Mesonichydae and are extinct; but in former times there were a number of different species. Some of these small-to-middle sized mammals started moving into the coastal regions. The disappearance of the dinosaurs 65 million years ago made it easy for the whale's ancestors to conquer the flatwater areas and to start hunting fish -- a powerful brain food. The paradise of fresh food in the oceans encouraged some of the ancestors to go totally into the water.   A couple of years ago, two interesting missing links were found in Pakistan. "Ambulocetus natans", 10 feet long, predators, have been living in lagunas like amphibia. They still had remnants of arms and legs, and the way they lived was very much like they way seals live today. The "Rodhocetus", who lived more in the water, had a body with many more modifications, such as a horizontal fluke and very small leg rudiments. The skeletal fossil of these so-called whale ancestors seem to be 50-52 million years old.

50 million years ago the "Archaeocetae" appeared. They spent their whole lifetime in water. One of the dominant predators of that time had a reptile-like skull, flippers instead of arms, and a body like a snake up to 65 feet in length, with a low water resistance.

The next step in dolphin's evolution is the appearance of the 18- foot-long dolphin-like "Dorudonts" and the similar "Basilosaurus" 40 million years ago. Modification of the earbones and a posterior placement of the nose is visible on them.

25-35 million years ago the cetaceans split up into Toothed whales (Odontoceti) and Baleen whales (Mysticeti). The Toothed whales named "Squalodontae" became popular 25 million years ago. They were very similar to the modern dolphins. They had a very simple echo-location system and different kinds of teeth.

The "Kentriodontae" had a much better bio-sonar system. They are the ancestors of most of the toothed whales. All these dolphin species had teeth of the same form and a highly evolved sonar system. Modern species, such as Bottlenose dolphins or Orcas, descended from these ancestors.  

BACK TO INDEX   The Cetaceans are divided into Baleen- and Toothed whales. The Baleen whales themselves split up into Grey whales, Right whales (like the Bowhead), and the Rorqual whales (like Blue whales, Fin whales, and Humpback whales).  The Baleen whales get their name from the material which comes down from the roof of their mouth. It serves as a filter system, which filters the water the whale catches for plankton. Most of these species are in acute danger.  

There are 68 species of Toothed whales. The biggest Toothed whale is the Sperm whale, Physeter catodon. The Beluga white whale and the Narwhal as Monodontidae. The family of Beaked whales, Ziphiidae has 20 species. 6 species of Porpoises, Phocoenidae, like the ones we find also in the Baltic Sea, and 5 different species of fresh water dolphins which exist in the Amazon River, in the Ganges, or in other big rivers are also included in the Toothed whale family. There are 26 species of oceanic dolphins,  and 6 species of round headed whales like the orca or the pilot whale, who are actually big dolphins. The Bottlenose dolphin is the most well known, and when I talk about dolphins, I'm mostly talking about this species that we can find all over the world  and near the coasts.

BACK TO INDEX   The brain of a Bottlenose dolphin (right pic.) can weigh up to 5 pounds. The neocortex is the area, like in a human's brain (left pic.), where the higher brain functions take place, such as memory, the power of association, creativity, the ability to learn, and judgment. The following numbers will give you some comparison between brains...

Human BrainDolphin Brain

Average Brainweight:


0.75 pounds


3.00 pounds


3.50 pounds

The relative brain weight in comparison to the body weight of the creature, in percent:

Chimpanse 0.70 %
Human 2.10 %
Dolphin 1.17 %

Some scientists have said that this means that a dolphin can never be as intelligent as "homo sapiens sapiens," because their bigger body would need a bigger brain. In comparison to the body weight, it is smaller. But dolphins do not wear clothes.

They have blubber, which is an insulating fat material that weighs a lot on land but contains just a small number of nerves. The design of the dolphin's body is determined by the absence of gravity in water, where the natural laws are different. Another argument against the dolphin's intelligence: the specific echo-location system occupies a lot of space in the brain. It actually is bigger than the visual sense, the opposite of humans. However, that's not surprising, because dolphins live in an acoustic environment. But it does not occupy the whole brain. There are lots of "silent "zones" -- areas where consciousness is located. And fresh water dolphins, for example, have a very effective bio-sonar system, but only small brains, and so do other species with a good acoustic sense.  The Cerebellum is the area in the brain for body coordination and balance. In the dolphin's brain, it is very well developed. One can observe the elegant body control when they do complicated maneuvers such as jumping and swimming in perfect syncronicity.

The Thalamus is the central point for the nerves that eventually reach the cortex. These are the main cable highways that connect the several parts of the central nervous system. The Thalamus in percent of the total brain weight:

Dolphin  2.65 %
Human   1.00 %

It is also interesting to look at the Hypothalamus, the location of the autonomic nervous system and instincts:  The Hypothalamus, in percent of the total brain weight:

Dolphin 0.17 %
Human 4.00 %

That may mean that humans are much closer to instinctive behavior than dolphins. Dolphins control every breath they take. They can concentrate blood in special areas of their body, which they do when they dive. Because of the very big difference between water and land, it is quite difficult to statistically compute the performance capabilities between a dolphin's and a human's brain. Neither the number of folds nor the relative brain weight nor the relative number of nerve cells and their size in the cortex can give us satisfying results.

But there is one method of comparison which brings some surprising facts to the surface: the investigation of the "Grey- cell-coefficient," which is the relationship between the mass of nerve cells and the total brain mass. That means:  

Volume of total brain substance / Volume of the nerve cells  = Grey-cell-coeff.

In order to understand this method, you have to know that the density of nerve cells in the cortex gets lower as the intelligence of a creature increase The lower the nerve cell density, the more neuro connections become possible. The lowest nerve cell density in our biosphere is found in Humans, Whales and Elephants. The evolutionary history and the difference of intelligence in mammals are easily seen when you compare the following   numbers:

(Dr.H.-G. Petzold -  Rätsel um Delphine):




=  8.5


=  15


=  24

Ape (Primate)

= 31-39


=  47



=  47

Another special thing in a dolphin's brain is the existence of "black brain substance", the so-called "Substanzia Nigra". Dolphins and humans have this area. It is located in the older middle brain. Produced there are important neuro-transmitters such as Dopamin and Endorphins. Dopamin is on one hand nessesary for the control of complicated body coordination, and on the other hand it involves the limbic system and the frontal part of the neocoretex where thoughts are located. Endorphins are produced when the body is exercised strenuously. They work to ease stress. Scientists thought that a dolphin's brain was the second one on earth to reach Primate status. That is an arrogant opinion. Think about it. The human brain has existed in its complexity for a hundred thousand  years. The dolphins have had theirs for 10 million years. No, it is not the dolphins -- it is WE who have finally reached Primate status! All these facts tell us that dolphins have a big brain and excellent cognitive abilities. Stories, as well as scientific experiments, give us this knowledge.

BACK TO INDEX   Intelligence is manifested by the ability to communicate. Lots of animals are able to do that. But the memory abilities and the power of abstract thinking of dolphins is only comparable with the modern human brain. The classic experiment, done by Dr. Javis Bastian proves that dolphins make plans and communicate about abstract ideas with their language....

Two dolphins, Buzz and Doris, were in captivity in a divided pool. In the beginning, they could see each other. In both parts of the pool, two switches had been installed. The dolphins were supposed to push the right switch if a light came on and stayed on, or push the left switch if the light came on and blinked. They learned quickly. But then the experiment got more complicated.  Doris had to wait for Buzz to push the correct button, and then she had to push the correct button, to get fish for both of them. The next step was to build a wall between the two parts of the pool which would not allow visual contact between the two dolphins. They could only hear each other, and only Doris could see the light signal.The constant light came on. Doris waited for her turn. Nothing happened, because Buzz couldn't see the light signal. Then Doris made a sound. Buzz reacted by pressing the right button for the constant light. Doris continued with her constant light button and they got the fish.

 Now, what does this mean? Doris realized that Buzz couldn't see the signal. She told him by sound that he had to press the correct button for the constant light, which was the right one. The experiment has been repeated 50 times, and Buzz was most of the time right, although he couldn't see the signal. That was the basis for the theory that dolphins can communicate about abstract ideas, such as left and right. Experiments with captured dolphins give us a lot of knowledge, but free-living dolphins can tell us so much more. There are lots of documents and stories which show us that dolphins act carefully and intelligently and prefer community.

BACK TO INDEX   We know that dolphins are able to exchange complex information. So now I want to talk about the communication channels dolphins use. Perception and communication are naturally connected with each other. Transmitters and receivers have to be good enough to transport the data.  

Dolphins actually do have a well functioning visual sense. The optical channel can be used for two types of visual communication. The first is passive, which means the whole body sends out its individual signals like scarred skin areas, color specifications, or fin profiles. The second is active, which means the exchange of information by body language. The eye of a dolphin is covered with a leather capsule which is very resistant to high pressures. To protect it from the seawater, it produces an oily substance. Incoming light goes through the cornea and the spherical lens to reach the retina. Under the retina there is a kind of mirror for amplifying the light intensity.The lens can change shape so that the dolphin is able to focus its eye quite well for good vision both under and above the water's surface. Because of their body structure, they have only a small range binocular optical field, which is limited by the size of their heads. With only one eye, monocular, they can also see what is happening behind them. In an upward direction, they are blind. "Spyhopping" whales and dolphins get themselves  in a vertical position and then turn around to actually scan the surroundings for interesting or dangerous things.

A dolphin's tactile sense is very well developed. Transmitters and receivers exist over the whole body, with special areas where lots of nerve endings make them very sensitive -- for instance, the flippers, fins, flukes, mouth, clitoris and penis.They touch and embrace each other often without the wish to copulate. For dolphins, the sense of smell is not relevant. Some regions of the mouth work as a chemo-receptor. The female whale shave rudimentary milk- producing glands which produce a transmitter substance. And one of the newest discoveries about whales is that the whale penis has chemo-receptors at the top to better find its way to the vagina.

BACK TO INDEX   The perception of and communication with sound is very important for dolphins, because it's dark at 300 or 600 feet  deep, and higher up the plankton limits sight. Water transports soundwaves more quickly and with less energy loss than air. Sound travels in water at almost 5000 feet per second. The acoustic channel of a dolphin has two parts: first, the common principle of communication, which means the exchange of information with sounds, like a language; and second, the high-tech biosonar echo-location system they have. This is an active system. Passive systems receive transmitted or reflected energy, such as light, for instance. The active SOund NAvigation and Ranging (SONAR) system sends out energy as ultrasound, which is reflected by the object, received back as an echo, computed in the brain and then projected there as a picture.   The frequency ranges up to more than 200.000 Hertz in River dolphins. The dolphin's SONAR receiver is very sensitive. Imagine, if you can, echos of small objects very much lower in volume than the clicking sounds the dolphins produce. The two ear capsules are not connected with the skull and they are well isolated from each other. They hang by elastic cords in an air-filled area. This creates a good perception of directional differences in sound. The funnel-shaped eardrum is fixed in a hard and thin bone structure. Here we find a separation into two receivers for two different frequency ranges. One is the tympanic bone, which receives the high frequencies. The lower frequencies reach the eardrum itself. Muscles in the middle ear can change the acoustic sensitivity to the frequency the dolphin likes. The cochlea in the inner ear analyzes the sounds and a large nerve transfers the information to the brain. But how does the sound reach the inner ear? An external ear would not fit the perfect hydrodynamics of the dolphin's body. Instead, there's just a little water-filled tube behind the eye which may transport the lower frequencies. The high frequencies are received by one fatty channel on each side of the dolphin's lower jaw. These work as acoustic antennas. The time- or phase delay between the two sides  makes it possible for the dolphin to compute the position of an object. 

BACK TO INDEX   How sound is being produced in the dolphin's skull seems to be clear now, because very intensive research has taken place in the last few years. First of all, I'm going to explain the common types of sounds dolphins produce. The whistles are analog sounds. A wide variety of sounds is available. The dolphin can combine frequency and/or intensity modulations of the sound wave it produces, along with the element of time, in uncountable ways -- which makes it difficult for humans to understand. Some characteristic whistles may be identified as "alarm", "help", or personal identification whistles, which the dolphins learn as babies. But the question remains whether something like a common syntax exists or whether the type of communication dolphins use is based on a completely different system. The frequencies dolphins use for communication include the human frequency range as well as ultrasound frequencies.

 Tursiops Common Whistle (66k)
Tursiops common whistle (66k)

(Whistle Abstracts)

The next type of sound very often produced by dolphins is the Click. Clicks are pulse sounds. A single click sounds for a very short time but contains a mixture of frequencies. The maximum energy or sound- pressure level is emitted as ultrasound. Different dolphin species prefer different frequencies. Bottlenose dolphins emit sonar sounds with the highest power between 110-130 KHz. Pilot whales use 30-60 KHz. The clicks are being used to locate objects; but they may also serve as a means of communication between them.  The third important sound group is the burst pulse sounds. They sound like barking or moaning. But if you analyze them with computers, you notice that these sounds are actually high frequency "click packages".   

 Tursiops click train (97k)
Tursiops click train (97k)

(Sonar Abstracts)

 Tursiops click train (97k)
Tursiops burst pulse (64k)

The acoustic sense can also be used with sounds dolphins  produce in other parts of their body, such as clapping the jaw, hitting the water surface with their flukes, or breaching. The range of instrumental sound through these means is big enough to use them for communication. The "let-the-bubbles-go-up "  game they like to play without producing any sound may be being used as transmitter. Other dolphins could receive the signals with their eyes or also with their echo-location system.  

Some different theories did exist about the location of the dolphin's sound generation.

The nasal sac theory...a little underneath the blowhole is a channel which leads to a system of elastic nasal sacs -- three pairs of sacs, all asymmetric, as is the whole skull of toothed whales. The nasal plug is located in between the two upper nasal sac pairs. When the air coming from the upper nasal sacs passes the nasal plug, the whole area vibrates.

The larynx theory...the larynx of a dolphin has no vocal chords. An extension of the larynx tube works like a vibrator, and the whole system is held in place by a strong muscle. To let the system vibrate, the dolphin pumps air through the larynx.

But the latest discoveries done with the help of high speed endoscopy and computer tomography, speak for the "dorsal bursae" theory. These tiny extensions of the melon tissue (also called:monkey lips)  enter the nasal airway. These structures move in correlation to the click repetition rate. The lips are powered by air, which is being compressed in the nasal sacs. The direct connection to the melon tissue couples the vibration with very little energy loss.  

(Dorsal Bursae Abstract)

The focusing of soundwaves is done in several areas of the dolphin's head. The melon is a flexible space filled with an oily substance, located above the beak-like upper jaw. It serves as an acoustic lens and as a good contact medium with the water because it changes its own density as it gets closer to the water. Therefore energy loss is low.  The melon alone can not explain the ability of the dolphin to focus sound so well. A parabolic boney structure, called the  acoustic shield, is located behind the melon as a reflector. The high frequencies are emitted along the body axis and the lower frequencies spread out from there. This plays an important  role in high resolution echolocation. Dolphins are able to identify small objects that we wouldn't be able to differentiate with our visual sense. They can analyze material by checking out its resonance frequency.   The speed of sound under water is five times faster than in air. The wave length of a tone is also five times more. That means that dolphins have to use high frequencies for better directional characteristics. In air, bass frequencies are not as easy to locate as high frequencies. In water, they have to use high frequencies to "see" small objects with their ears. When the frequency is too low and therefore the wave length too long, the emitted wave could miss a small object.  Dolphins are also able to scan or x-ray other individuals. By scanning each other, the individuals in a group may gain more details about their status. Here we see that echo-location is an important part in dolphin communication. It seems to be possible for dolphins to emit click-coded pictures while communicating by whistles. So they don't need a word or symbol for "mackerel" -- they may just transmit the picture.

BACK TO INDEX   Now let me say something about Interspecies Communication. This subject could fill lots of speeches or lectures, and a great number of dolphin-friends have dedicated their life to the question of whether dolphins will one day talk to us. In the past dolphins had to learn English and humans tried to learn 'Dolphinese'. Computers and other technical equipment to analyze the dolphin's language might help but nothing really big has happened so far. One of the biggest barriers may be the big deviation in the time required to process information. The human articulation can be measured in a tenth of a second; the dolphin's in milli- or microseconds. For a dolphin, our language might sound like an audiotape played much too slow, and their language is much too    fast for humans. I think that A real-time communication with a language that humans could understand hasn't got a chance. Other ways have to be explored, such as communication using different media, like music. From my own experience, body language and telepathy might also be possible. It's up to you to create a new idea in Interspecies Communication. No book and no lecture can give you the feeling you get when you come in touch with a dolphin. On an individual level, you can find personal contact. Friendship with an intelligent species and with the whole biosphere is for me the gateway to the future of Interspecies Communication.



Thanks to all the authors for their information!

Source literature:

Dolphin Sound and Communication Abstracts - Monaco 1998

Jim Nollman - Die Botschaft der Delphine

Ric O'Barry - Das Lächeln des Delphins

John May - Das Greenpeace Buch der Delphine

Erich Hoyt - Alle Wale der Welt

Antony Martyn - Das große Bestimmungsbuch der Wale u. Delphine

Dr. John-C.Lilly - Communication between Man an Dolphin

Whitlow W.L. Au - The Sonar of Dolphins

Petra Deimer - Wale und Delphine

Heathcote Williams - Kontinent der Wale

Heathcote Williams - Delphin

Giorgio Pilleri - Die Geheimnisse der blinden Delphine

Grzimek - Säugetiere 2

Joan McIntyre - Der Geist in den Wassern

R.Breier/J.Reiter - Delphingeschichten

Jacques-Y. Cousteau- Delphine

Jacques-Y. Cousteau- Wale

Steniut - Delphine - meine Freunde

Dr.H.-G. Petzold - Rätsel um Delphine

Theodor Dolezol - Delphine - Menschen der Meere

M.Klima u.v.a - Handbuch der Säugetiere Europas Band 6I-A, 6I-B (2 Bände)

Mark Carwardine - Whales, Dolphins and Porpoises

Kenneth Norris - Dolphin Days

W. Pflumm - Säugetiere





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