DOLPHIN LANGUAGE

Dolphins just don't know when to shut up!


In fact they are almost making some kind of sounds. These are either about navigation and understanding their surroundings or about communication with other dolphins.  

Echolocation sounds are made in their nasal passages just below their blowholes, and are called clicks. Clicks are sometimes produced very close together and in strings. They sound like buzzes or chirps, and beamed forward from a special "lens" in the dolphin’s head. These sounds are produced behind the melon, an oily, slightly off-center lump that makes up the dolphin’s forehead. The sound waves are focused forward through it.

Scientists don't really know how the melon works, but it does seem to amplify and clarify the dolphin’s echolocation sounds. The dolphin's echolocation is so good that in one experiment, a dolphin located a marble-sized sphere at more than the length of a football field. 

Dolphins can produce high-pitched whistles and squeals in their larynx. These can rapidly change pitch in the same way we change the pitch in our voice. As far as scientists can tell, the whistles are a form of communication with other dolphins, and squeals are used to express alarm or sexual excitement.

Dolphin Communication

There have been lots of studies done to try to decide if dolphins actually have a language. Many of these studies have not been done very well and there are some extravagant claims that aren't supported by fact.

Others take the view that the dolphin's sounds are of no significance and that they are little more than fish. This point of view makes exploitation and even killing if these incredible mammals even more justifiable.

Most scientists feel that dolphins are highly intelligent. They have a greater brain-to-body-weight ratio (important in determining real intelligence) than any other mammal besides man. The appearance of the dolphin brain is similar to that of a human brain.They have brain ratios twice the size of any of the great apes. Some researchers place them in approximately the same category as our early humanoid ancestors. 




There is no doubt that dolphins communicate (like many other animals). We know that they communicate emotional states, danger, and the location of food. Their communication also seems to build group awareness within the pod.

But do dolphins actually have language?

The answer seems to be "yes". Dolphins tend to stay within their own pods, and may have trouble understanding outsider pods. In some studies individual dolphins appeared to have names. Dolphins used specific whistles in the presence of certain other dolphins. Different whistles were used with different dolphins as if calling them by name. 




While not proof, dolphins, like humans, take turns when making sounds as if information is being passed back and forth. Also like humans, dolphins use specific patterns in their "language".

Dolphins are indeed amazing mammals. Perhaps one day we will understand them better and be able to communicate with them. In the mean time they deserve our respect and a healthy ocean to swim in.

DOLPHINS AND NAVY SONAR

Dolphins and Man-Made Sonar

Because of millions of years of evolution, dolphin echolocation abilities are much superior to those of any man-made device. For this reason, the US Navy have been studying them for years in order to improve their own sonar. What they've found has been surprising.

Dolphins are incredibly good at distinguishing their own echolocation sonar even in very noisy underwater environments – and in fact are very good at locating the drift nets that entangle and kill so many of them, raising the question of why they are still often trapped in them. It has also been found, though, that some noisy locations confuse dolphins, perhaps explaining why dolphins often ground themselves in areas where Navy ships using active sonar are performing maneuvers. 

Could the clumsier man-made sonar be using frequencies the dolphins associate with something else? Or perhaps it’s like looking into a strobe light for them. Whatever the explanation, the Navy is interested in eradicating the problem.

Dolphin Beaching

It’s the most tragic thing a dolphin lover can see: a pod of dolphins that have apparently killed themselves by swimming onto a beach and lodging themselves there. 

Why do dolphins do this?

The most prominent theory currently is that something confuses their echolocation, “blinding” them to the location of the beach in relation to the open ocean. Since many beachings happen near man-made sonar activity, it’s possible that this impacts them. 

 A pod of beached Pilot Whales

These bursts of man made sound can reach 240 decibels (billions of times more powerful than the level that causes hearing damage in humans). During testing off the California coast, noise from one of the Navy's low-frequency sonar systems was detected across the full width of the northern Pacific Ocean.

How Sonar Harms Whales

By the Navy's own estimates, even after 500 kilometres, these sound bursts can retain an intensity of 140 decibels -- a hundred times more intense than the level known to affect the behavior of large whales.

Some very recent autopsies of beached dolphin bodies show a very high percentage of damaged hearing, suggesting that a very powerful sound somewhere may have basically blown out their hearing. Dolphins see quite well, but without their ears they are disoriented and blinded. And when one dolphin beaches itself, the others are at risk because they will try to help him.

However a beaching is initiated, it’s likely that it has much to do with how a dolphin perceives sound. Hopefully, we’ll soon understand enough about dolphin hearing to be able to prevent these tragedies.

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AMAZING DOLPHIN ECHOLOCATION by Dr. Gerry Goeden

Dr. Gerry Goeden is a marine biologist working in the Andaman Sea.

When the mammalian ancestors of whales began to move from land and back into the sea they were faced with huge problems. A major difficulty was that they had lost the evolutionary advantages necessary for a successful aquatic life; underwater vision was difficult, they were poor swimmers, and they were easy prey for the huge sharks that inhabited the ocean from 50-75 million years ago. In fact, sharks may have been their greatest problem since sharks had already perfected incredible senses of smell, sound detection, and the ability to receive the invisible electrical fields produced by other animals. Not only were the sharks more efficient fishermen but large sharks could detect, out-swim, and then capture ancient whales.

Many whales solved this problem with the help of evolution by becoming so large that even large sharks couldn’t eat them. They also stopped competing with sharks for food by changing to a plankton diet. Their descendants are the baleen whales of today: examples are the Right Whale, Gray Whale, and Humpback Whale.

Other whales evolved to compete with the sharks. They retained their teeth and fish diet but became faster and developed an incredible sense of echolocation which allowed them to ‘hear’ the approach of huge sharks long before they could be seen.

Because sound travels through water better than light does, the ability to make a sound and then interpret the ‘meaning’ of its echo, allowed the toothed whales to find food when sharks couldn’t and avoid predators before they could get too close. Whale echolocation today may be the most sophisticated sensory system in the entire animal kingdom. Unlike our own vision, echolocation for whales carries three dimensional information. Toothed whales can ‘see’ inside and through many objects and reflected sounds seem to allow them to ‘see’ around or behind things.

The information that can come back by echo depends on the frequency of the sound. Low frequency travels long distances and has less detail while high frequency is shorter range with high definition. To get the whole picture some whales ‘sweep’ the frequency range between high and low frequencies. When they home in on prey these ‘sweeps’ sound like a continuous creaking sound.

When humans send out radio signals for locating things (radar), we focus the signal into a beam using a specially shaped antenna. Toothed whales do the same with sound using special fat deposits in the top of their heads and in their jaws. This fat is different from the other fat deposits in the whale’s body and fits into specially shaped areas in the jaw and skull. We use facial muscles to frown or smile but whales seem to use their muscles to adjust the shape of the fat deposit and focus the sound beam.

These special fat deposits are most remarkable in the sperm whale where they may weigh several tonnes. In dolphins the deposit looks like a rounded lobe on the front of the head and is called the melon.

The frequency of toothed whale sounds ranges from 40 Hz to 325 kHz. A list of typical sound levels is shown in the table below (from Wikipedia). A level of 120dB causes hearing damage and pain in humans.

Kind of Whale	Sound	Broadband  level (dB)
Sperm whale	clicks	163–223
Beluga whale	echolocation clicks	206–225
White-beaked dolphin	echolocation clicks	194–219
Spinner dolphin	pulse bursts	108–115
Bottlenose dolphin	whistles	125–173

We still don’t know much about all this whale engineering but it seems to work like this:

• A powerful sound is generated by ‘vocal cords’ (phonic lips) within the whale
• As the sound radiates out, the melon focuses it like a lens focuses a beam of light
• The sound beam hits an object in the sea and is reflected back
• The teeth in the lower jaw act as ‘antennas’ collecting the echoes
• Fat deposits in the lower jaw carry the sound to the inner ears
• The complex brain interprets the echoes and constructs a ‘picture’ of the object

In this way a whale may see a picture with sound similar to the picture we see with light. It is clear though that the picture is only as good as the information processor that untangles the complex echoes coming back to the whale. To see with sound, whales have also evolved very large brains.

Many people believe that the large brain means that dolphins in particular are the philosophers of the sea. The truth is that a large part of that brain seems to be used for processing and remembering echo information necessary for feeding and navigation and relating to other whales with their own acoustic information.

The ancestors of whales had ears for hearing on land. Whales still have ear openings that lead to the inner ear. In baleen whales these openings are filled with a hard wax but in the toothed whales the hole is open. There is evidence that dolphins can hear in air and water with these openings but they probably play a very small part in echolocation.

The baleen whales are not hunters like the toothed whales and have not developed the elaborate clicks and whistles to ‘sweep’ their prey. It has been suggested that baleen whales may use their stored echo-soundings to create complex three-dimensional maps of the ocean floor thousands of meters below for use in their long annual migrations covering tens of thousands of kilometers.

Illustrations are from Wiki-commons.

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DOLPHIN INTELLIGENCE by Dr Gerry Goeden

There are many times that dolphins have rescued swimmers or fought off attacking sharks at real risk to themselves. Because of these actions, humans tend to feel there is a special bond between dolphins and themselves and that this bond is based on mutual intelligence or a wished for understanding.

From as early as the 17^th century scientists have been impressed by the size of dolphin brains and rated them near the top of the ‘non-human’ intelligence list. Many cetaceans (whales) do have large brains and, relative to body size, toothed whales have larger brains than baleen whales. In fact, the relative brain size of bottle nose dolphins is nearly the same as that of humans. Dolphin brains range from about 0.25% to 1.5% of their body weight and human brains are about 1.9% of our body weight.

Another measure of brain development is based on the number of folds in the grey matter (cerebral cortex). This is the part of the brain that gives us conscious control of our bodies and thoughts. Toothed whale brains have more folding than baleen whales but much of this is taken up for sound production and processing. Toothed whale brains, like the dolphin’s, have folding that resembles that of hoofed animals like horses and deer.

We don’t know if dolphins have a language but we do know that they share information about their surroundings, their emotions, and their identity through acoustic whistles and clicks.

Memory experiments with dolphins showed that their picture of the world and their ability to remember it was better when based on their sonar and not so good when based on sight. Their memory was best when they could use sonar and sight together.

Dolphins have also been taught ‘words’(using hand signals) that can be put together in two-word sentences like “get ball”. Scientists found that they understood these sentences about 80% of the time. Able to grasp the basics of human language, it may be possible to communicate in two and three word format with dolphins in the future. If we do decide to talk with dolphins it will be best to choose our subjects wisely since research shows a large variation in ‘intelligence’ among species.

We think of intelligence as the ability to understand our surroundings and process information so that we can react in the most favorable way. In this way intelligence is not the same as instinct where reactions are ‘pre-programmed’ in the brain. In the animal kingdom, species with higher intelligence tend to be social animals that live in groups.

It is thought that the evolution of intelligence is related to the need to understand group dynamics and the individual’s place within them. The ‘smarter’ dolphins operate in social structures similar to dogs and primates.

Having a well developed brain and intellect; humans are always quick to make lists showing the relative intelligence of other animals with us at the top. To be fair, we must always ask the question: “How intelligent would we be in the dolphin’s world of sound and social behavior; in a world without landmarks and signs; and without shelter and an organized food supply?”

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DOLPHINS IN CAPTIVITY

One of my best friends over the years was a marine mammal veterinarian. He looked after the health of animals like dolphins, sea lions, and whales while they were in captivity. A great but very controversial job!

Because all of the marine mammals are fairly intelligent, they require stimulating environments. Over the years many people have come to believe that being held in captivity just doesn’t meet those requirements and that these ‘more cognitive’ animals need to lead more acceptable and ‘freer’ lives.

We often talked about the pros and cons of marine mammals in captivity; and yes, there are pros and cons but these seem to be shifting toward the negative and so collecting and moving marine mammals is now very difficult. Most new additions are offspring of those kept in captivity for many years.

Let’s look at the arguments.

First let’s look at some of the biological questions;

Q. Dolphins eat fresh food in the wild but in captivity, they have to eat frozen seafood. Does that affect the dolphin's health?

A. Dolphins are aggressive predators and spend as much as half of their time hunting. In captivity, they don't have to do this and miss out on some of their behavior. 'Fish' is frozen not only to make it easier for aquariums to store but to kill parasites that invade the dolphin's digestive system in the wild. Frozen seafood is also supplemented with vitamins and minerals. Dolphins are too expensive for aquariums to risk their health because of bad food. I would say that they eat as well or better in captivity.

Q. How big would a tank have to be to keep dolphins in captivity?

A. This is a difficult question because in the wild, there really aren't any border; dolphins can go where they like and travel great distances. In the wild they can swim up to 200 km a day and some species spend much of their time in very deep water. Others like the Chinese Humpback dolphin don't move around much in the wild and stick to the familiar surroundings.

Q. Are dolphins physically stressed when they live in captivity?

A. Dolphins are highly intelligent animals and live in complex social groups. It is argued by aquariums that dolphins live longer in captivity due to less disease and predation. " Pro-dolphins groups argue that they live longer in the wild because they lead more natural life and belong to social groups. Stress and odd behaviors are sometimes seen in dolphins held in aquaria but then they aren't subject to shark attacks and parasites either.

Q. Is it a good idea to put different 'kinds' of dolphins in the same tanks?

A. Captive dolphins often come from different regions and populations. While wild dolphin groups do stick together, there is quite a lot of movement of individuals between groups. If this were not so then dolphins would quickly become inbred and genetically weakened.

Dolphins in captivity sometimes share tanks with other marine mammals but this is avoided by better aquariums. Competition and fighting between species damages the animals and my friend's medical work was very expensive.

Now lets look at some of the ethical questions that relate to keeping intelligent animals in captivity;

Q. Do dolphins enjoy performing in shows?

A. Because of their intelligence and social nature they do enjoy challenging activities (performing). Most of the performance behaviors are based on their natural behaviors and dolphins will not do them if they don't feel like it. They literally go on strike. Left alone, they will play with balls and hoops just as they will play with debris and seaweed in the wild. Another question could be "Do dolphins prefer to play with balls in captivity or seaweed in the wild?" My guess is they would find the wild much more interesting.

Q. Dolphins and other marine mammals have very large brains so are very intelligent. Do they suffer mentally in captivity?

A. The Indo-Pacific Bottlenose Dolphin (Tursiops truncatus) has an absolute brain mass of 1500 - 1700 grams. This is slightly greater than that of humans (1300 - 1400 grams) and about four times that of chimpanzees (400 grams). They are intelligent but most of that brainpower goes to processing underwater sound and echo-location. Our best estimate is that they are of similar intelligence to elephants and some apes. So, yes, they would suffer if they didn't get a stimulating environment. we don't know if they long for the wide open spaces.

Q. Are dolphins forced to live in mentally stressful situations?

A. While aquariums do their best to remove stress, the fact is that limited space and social interactions take their toll. Dolphin males spend a lot of time fighting over females and the loser finds it easier to get away in the wild; there can be more damage through continued aggression in aquaria IF the managers don't keep competing animals apart. Unnatural social relationships are probably the biggest mental problem faced by dolphins in captivity.

Q. Would dolphins escape if they could?

A. An interesting question. The U.S. Navy uses dolphins to search the bottom of ships for explosives, locate mines in harbours, and ‘spot’ enemy divers. The dolphins are released from captivity and go off to do their jobs. When they are finished they return to captivity.

My friend, the marine mammal veterinarian, says that like dogs dolphins build bonds to humans and see us as their ‘family’. And like dogs they come home after they have been released.

Have a look at some of the photos of his work with dolphins.

Prior to 1980, more than 1,500 bottlenose dolphins were collected from the United States, Mexico, and the Bahamas, and more than 550 common and 60 Indo-Pacific bottlenose dolphins were brought into captivity in Japan. By the late 1980s, the United States stopped collecting bottlenose dolphins and the number of captive-born animals in North American aquariums increased from only 6 percent in 1976 to about 44 percent in 1996. It is well over 50 percent now.

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