Red marked places are mistakes i made.
Biology
Listen to part of a lecture
in a biology class.
We’ve been discussing
animal communication. Um, today we are going to talk about dolphins. Now,
dolphins make a wide range of communicative sounds, and display something called vocal
learning, which is the ability of an animal to
modify its vocalizations based on its experience
with other animals. There are many types of dolphin vocalizations.
We still don’t know their precise meanings – partly, I suppose,
because we haven’t really tried that hard to
figure out their precise meanings – but we do
know that dolphins use vocalizations as a way of
communicating with one another. And we’ve categorized their vocalizations into three types: whistles, clicks, and burst pulses.
The dolphin whistles are very high frequency sounds, ah partially
above the range of human hearing. What’s fascinating is, each dolphin has a signature whistle, which is unique to each individual
dolphin. It allows them to call to and
identify each other. Jennifer?
Kind of like learning someone’s name? So… do dolphin parents choose names
for their children?
Well, again, that’s
something we don’t know, but we do know that no two signature whistles sound identical. And, members of the same family,
their signature whistles
have similar elements. Dolphins use them as contact
calls – ah they call to each other while travelling
and foraging. It helps
keep the group together, and helps mother and
children find each other. Think of it like …. if
you were travelling in the forest with one other person who was just
out of sight, you’d
call out, “are you there?” and the other person would
respond. But if there were several people in the forest,
you would have to call that person’s name to call to
them. In addition to whistles, dolphins produce
clicks which are actually sonar or sound waves.
They use clicks to communicate, but, more
importantly to navigate and hunt. How?
Well, the sonar
clicks bounce off objects, and then dolphins convert the incoming signals into
a three dimensional picture… a mental map of
what’ around them. Their clicks are extremely sensitive
and accurate. Their sonar clicks are also very
strong. And there is the theory that one reason dolphins
swim side by side is to avoid interference from
each other’s sonar clicks. Interference would be confusing… it
would prevent them from getting an accurate picture
of their surroundings. And what’s interesting is,
dolphins will turn off their sonar when another dolphin
passes in front. The third category of dolphin’s vocalizations is burst pulses. These are all this
other sounds the dolphin makes – suawks, squeals, barks, groans, and so on. Burst pulses are used to display aggression, show dominance
and attract mate. But whistles,
clicks, burst pulses aren’t the only ways dolphins communicate. Does anyone remember any other ways?
In the book, it said that they also slap their tails against
water. Oh, and … the air that comes out when thye
breathe or whistle … the … ah … the bubble streams? They can control how the air bubble
streams come out? I thought that was really interesting.
Yes, the bubble streams are very interesting. Dolphins can
identify and locate each other by their bubble streams
and they can imitate the bubble steam patterns of other dolphins… sort of like saying hello.
So as you can see, dolphins use many sounds and behaviors to convey messages to each
other. I’d like to tell you about when I was a graduate student … and … I spent
one summer on a boat in the Atlantic Ocean studying
marine life. One morning, there were about 25
dolphins swimming with the boat. We can hear
their whistles and clicks as they called to each
other. Now, we were there as impartial
scientists, to do research, but… how could we not notice the beauty as the bubble streams made
patterns in the water and the dolphins appeared
to dance and play? It’s wonderful if you do field work and actually experience something you‘ve been studying
in a class room. So if you ever have the opportunity, go for it!
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