Tuesday, 16 June 2015


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.

Thursday, 23 April 2015


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.

Sunday, 19 October 2014


We have all heard the sounds dolphins can make when they seem to communicate with each other or with their human trainers. We also know that they can navigate with their eyes covered using echolocation.

Research has shown that dolphin echolocation is so good that they can detect a 75 mm object at distances up to 100 m away.

The debate over dolphin language goes on and will until we can 'crack' the code. In the mean time there is mounting evidence that they do communicate ideas in a sophisticated way.

Scientists have shown that the same species of dolphin living in the English Channel stick to either the French or English side and never mix. Is it possible they stay apart because they don't speak the same language?

At the moment we believe they have vocabularies similar to apes complete with food sounds, danger sounds, and 'seeking' sounds. There are many more sounds that we don't understand at all. 

Dolphins can assemble short strings of sounds the way we make sentences. We are also pretty sure that they use distinct sounds to represent themselves; they have a name and this is recognized by other dolphins.

Noise probably isn't a problem for dolphins in captivity but it is for wild dolphins. In Datai Bay where I work, I sometimes hear dolphin whistles but they are often drowned out by the sounds of trawlers and heavy ships passing.

Lots of ambient noise would be like trying to chat at a rock concert. This could make communication and echolocation pretty difficult. More about this in another post.

Saturday, 4 October 2014


In an amazing experiment with a captive dolphin in Florida Dr. Bruck played a recording of the signature whistle of a 2 year old female to a 25 year old male. The male and female had been together 20 years earlier when the male was only 4 years old. The result? The captive male recognuized the whistle of his female companion after 20 years separation.

So, what does this mean for wild dolphins?

In the wild, dolphins live for about 20 years but many live as long as 45 years. That means that most dolphins are able to remember the "names and identities" through signature whistles of many of the other dolphins they build bonds with.

On the 'memory score card' dolphins rank in the top one or two non-human memory stakes. Only the elephant is said to be able to remember for periods of 20 years or so and we don't know if elephants can remember all the elephants they befriend along the way.

Why dolphins' social memories persist so long is unclear. Dr. Bruck says that dolphins exhibit sophisticated social connections that follow a "fission-fusion" model. Dolphins may separate from one group and "fuse" with other groups many times over. Such relationships could have required a growth in memory capacity to avoid social conflicts. But it's also possible that memory is just one facet of the advanced mind that evolved in dolphins for other reasons.

"Why do they need this kind of memory? I'm not sure they do," Bruck said. "The cognitive abilities of dolphins are really well developed, and sometimes things like this are carry-along traits. But to test whether this kind of social memory capacity is adaptive, we would need more demographic data from multiple populations in the wild to see if they experience 20-year separations."

The emergence of advanced memory in marine mammals as well as in humans shows that in evolution, "there are lots of ways to get from point A to point B," Bruck said. "It's nice to see this kind of ability in a non-primate, as this is a great example of convergent evolution."

"So far no one has been able to test what signature whistles signify in a dolphin's mind. We know they use these signatures like names, but we don't know if the name stands for something in their minds the way a person's name does for us," Bruck said. "We don't know yet if the name makes a dolphin picture another dolphin in its head."

For his next round of research, Bruck said, "That's my goal -- show whether the call evokes a representational mental image of that individual.


Tuesday, 23 September 2014


New research reveals that dolphins can recognize the whistles of old "tank mates" after a separation of 20 years.This is the longest social memory recorded for any species other than humans.

The remarkable memory  is another indication that dolphins have a level of cognitive ability comparable to only a few other species, including humans, chimpanzees and elephants. Dolphins' talent for social recognition may be even more long-lasting than facial recognition among humans. This is because human faces change over time but the signature whistle that identifies a dolphin remains stable over many decades.

"This shows us an animal operating cognitively at a level that's very consistent with human social memory," said Jason Bruck, who conducted the study and received his Ph.D. in June 2013 from the University of Chicago's program in Comparative Human Development. His study is published in the current issue of the Proceedings of the Royal Society of London B.

To establish how well dolphins could remember their former companions, Bruck collected data from 53 different bottlenose dolphins at six facilities, including Brookfield Zoo near Chicago and Dolphin Quest in Bermuda. The six sites were part of a breeding consortium that has rotated dolphins and kept records on which ones lived together, going back decades.

"This is the kind of study you can only do with captive groups when you know how long the animals have been apart," Bruck said. "To do a similar study in the wild would be almost impossible."

"Signature whistles" offer means to test memory

Other studies have established that each dolphin develops its own unique signature whistle that appears to function as a name. Researchers Vincent M. Janik and Stephanie L. King at Scotland's University of St. Andrews reported earlier this year that a wild bottlenose dolphin can learn and repeat signatures belonging to other individuals, and answer when another dolphin mimics its unique call.

Bruck played recordings of signature whistles to dolphins that had once lived with the animals that made the calls. Determining whether the dolphins recognized their old companions required a comparison of how they responded to familiar calls versus calls belonging to dolphins they had never met.

Bruck would play recording after recording of signature whistles that the target dolphins had never heard before. His initial studies showed that these "dolphins get bored quickly listening to signature whistles from dolphins they don't know." Once they were habituated to the unfamiliar calls, Bruck would play a recording of an animal that he knew the target dolphin had lived with.

The familiar calls often would perk up the dolphins and elicit an immediate response.
"When they hear a dolphin they know, they often quickly approach the speaker playing the recording," Bruck said. "At times they will hover around, whistle at it, try to get it to whistle back."
To check that the response was the result of recognition, Bruck also would play a test recording of an unfamiliar bottlenose that was the same age and sex as the familiar animal. All the behavior was scored according to how quickly and to what degree the animals responded.

A clear pattern emerged in the data: Compared with unfamiliar calls, dolphins responded significantly more to whistles from animals they once knew, even if they had not heard the calls in decades.

Saturday, 9 August 2014


When we say "think" we are talking about cognitive ability. And like just about everything else in the world, we tend to measure cognitive ability in our own terms.

In terms of brain size, dolphin brains are significantly larger than our own. If we relate brain size to body mass then we slip into the lead and dolphins come in second. The question is what do dolphins do with all that neural material?

Neuro scientist, Dr Lori Marino, says that some dolphin brains exhibit features correlated with complex intelligence. They have a large expanse of neo-cortical volume that is more convoluted than our own, extensive insular and cingulated regions, and highly differentiated cellular regions.

Dr. Marino went on to say, "Dolphins are sophisticated, self-aware, highly intelligent beings with individual personalities, autonomy and an inner life. They are vulnerable to tremendous suffering and psychological trauma."

While presenting information at the American Association for the Advancement of Science conference (AAAS) in San Diego, she spoke against keeping dolphins in captivity. "Our current knowledge of dolphin brain complexity and intelligence suggests that these practices are potentially psychologically harmful to dolphins and present a misinformed picture of their natural intellectual capacities," Marino says.

Because we are unable to communicate with dolphins, it is difficult to assess their cognitive or thinking ability. Instead scientists use indicators of 'levels' of ability. One indicator is self awareness.

Dr. Marino found that dolphins were able to recognize themselves as distinct from other dolphins in a mirror. This ability is found in higher primates like ourselves and in elephants.

Can dolphins think?

The answer is a definite yes. We don't know what they think about but can guess that their thought processes are complex and relatively sophisticated.

If they think about their social group, hunting, and navigation then they might not spend a lot of time thinking about confinement versus a life in the ocean.

If they have sophisticated thoughts and can compare an aquarium with the ocean then they could be quite miserable in captivity.


Monday, 16 June 2014


I spent several years working from an island field station on the Great Barrier Reef. Although most of my time was spent working long hours with fish along the reef slope, I came to recognize a group of three bottlenose dolphins that regularly passed through my study site. They never came close but seemed interested in what I was up to. I found that if I ignored them and hammered small steel pins into the bottom (used as markers), the dolphins would come up behind me and look over my shoulder. If I turned, they were gone in a flash.
I’ve also spent hours cleaning windows in an oceanarium when I was going through university. Lots of things swam around behind me then but I feel that the dolphins were either bored or had little interest because of the regularity of my job with the brush.
Now I am working in Datai Bay and often see Chinese Humpback or White Dolphins. Again they are curious but incredibly shy.
The Chinese White Doplhin

Let’s look at a single question based on what we know about dolphins today;
Do dolphins have emotions and feelings like our own?
If we look at dolphins anatomically, we see that they have a well developed limbic system. The limbic system is a collection of neural material that is part of the ancient mammalian brain. It is common to mammals.
The limbic system supports a number of functions including emotion, behavior, motivation, long-term memory and olfaction. In humans it has a lot to do with our emotional life and is vital to the formation of memories.
But as a scientist, I have to ask the question, “Do we know if the limbic system in dolphins performs the same role as in humans?” The answer is we don’t know.
We do know that memory for dolphins are very important since they live in a world with only visual and olfactory clues for navigation. We might assume that as long lived animals, the amount of memory stored would be large.
A pod of wild dolphins must use a good memory map for navigation.
We also know that dolphins ‘express’ emotion. I say this because we can’t really know what they are feeling; we can only imagine our feeling in the same situation.
An example would be the loss of an offspring. More advanced mammals seem to behave as we do and mourn. Again this is an interpretation. Less advanced mammals and even many non-mammals may seem to do the same.
Do dolphins enjoy human contact?
Unfortunately, the scientific facts just aren’t in yet. From my perspective dolphins have emotions but not at the human level. They show curiosity similar to other advanced mammals but again from my perspective they are not as emotional or curious as monkeys and apes (just my opinion!).
My next post will look at what we know about dolphin intelligence and ask;
“Do dolphins think?"