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.

SONAR AND WHALE STRANDINGS

I was recently speaking with a group of students visiting from Mexico when one asked, "Why do whales beach themselves?" The answer isn't an easy one!

Sonar comes from the contraction of the phrase, ‘sound navigation and ranging’. In more technical terms active sonar is the use of sound sent out into the water and then reflected to determine the location of an object. Passive sonar makes use of listening for sounds and triangulating their source. The development of sonar was for military purposes but a co-researcher of mine uses passive sonar (does not emit sound) for location, counting, and identification of whales.

Does sonar cause whale strandings? 

Two thousand years ago Aristotle wrote: “It is not known why they sometimes run aground on the seashore; for it is asserted that this happens rather frequently when the fancy takes them and without any apparent reason'.”

Clearly there have been reasons for whale strandings before the advent of military sonar. This does not prove that military sonar is not responsible for some of the strandings today.

When active sonar is used an intense burst of sound is released underwater. These sweep the ocean like a floodlight, revealing objects in their path as echoes return to the source.

French F70 frigates  are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C towed sonar

These bursts of 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.

Many of these beached whales have suffered physical trauma, including bleeding around the brain, ears and other tissues. 

 A 1986 West Australian stranding of False Killer Whales

These injuries are similar those resulting from underwater explosions or barotraumas (injury from pressure). I have seen these injuries and provided forensic evidence in legal cases dealing with underwater explosives. They found that many more animals were affected, injured, or chased from the area. Scientists are concerned about the cumulative effect of these bursts of sound on marine animals.

“The Navy’s most widely used sonar systems operate in the mid-frequency range. Evidence of the danger caused by these systems surfaced dramatically in 2000, when whales of four different species stranded themselves on beaches in the Bahamas. Although the Navy initially denied responsibility, the government's investigation established that mid-frequency sonar caused the strandings.” according to the Natural Resources Defense Council. Similar mass strandings have occurred in the Canary Islands, Greece, Madeira, the U.S. Virgin Islands, Hawaii and other locations. 

Can we build less dangerous sonar?

It is possible to build sonar systems that use frequencies or power levels that will not harm whales. The problem is that we are ethically unable to carry out research that would deliberately harm whales so we can measure the effects. We can not have controlled exposure experiments because at least 20% of the test animals would have to be stranded, injured, or die to meet statistical analysis requirements.

A Supreme Court decision in the U.S.A. (2000) stopped the U.S. Navy from testing powerful sonar systems in most of the world's oceans after a federal judge ruled that it could "irreparably harm" whales, dolphins and fish. This decision does not relate to other Navies.

The other issue has to do with military competition and security. Supporters of more powerful sonar will claim that we are putting whale safety ahead of national safety if we limit what only some countries can test.

 Humpback whales are among the marine mammals effected by sonar.

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