Copyright 1995 Jonathan Bird/Oceanic Research Group, Inc.
All Rights Reserved
Perhaps no other sea creature captivates and delights us as does the dolphin. Humans and dolphins have been intertwined in culture, religion, myth and folklore since nearly the beginning of civilization. Dolphins appear on coins, pottery, statues and even cave walls in many cultures from all over the world and throughout recorded history. Ancient Greeks worshiped dolphins. In their culture, it was illegal to harm a dolphin in any way. Clearly, we humans believe that there is something special about dolphins. Join us now as we enter the dolphin's world, to meet this fascinating and curious creature of the seas.
In the simplest terms, dolphins are marine mammals, meaning that, like land mammals, they have lungs and breathe air, they give birth to live young, and they feed their young milk. Dolphins are classified in the same taxonomic order as whales, making them basically just small whales. Evolutionary biologists believe that all of the whales and dolphins actually evolved from a land mammal which took to the seas to hunt for food over 100 million years ago. Nowhere is this more evident than in the skeleton of the dolphin, which still retains the finger bones of its ancestors, even though the fingers have long since been lost in favor of a flipper. The rear legs have been lost altogether. Instead, the dolphin has a powerful tail called a fluke.
Over millions of years, the body of the dolphin has evolved into a sleek, torpedo shape, allowing it to pass through the water with as little resistance as possible. The powerful fluke combined with the hydrodynamic shape allow the dolphin to swim at speeds of over 30 miles per hour through the water.
Because the dolphin has lungs, it must surface to breathe, and hold its breath while underwater. Again, evolution has equipped the dolphin well. Its blowhole is actually the dolphins nose, located conveniently on the top of its head, so it can take a breath without sticking its whole head out of the water.
Our filming expedition took place in the Bahamas, where we searched for wild Spotted Dolphins all day long every day for several weeks. There is no certain way to find dolphins, and in fact, the best way is to let them find you! Dolphins are naturally playful, and one of their favorite things is swimming in the bow wave of a boat. Because the boat pushes water out of the way as it churns through the ocean, the dolphins can actually surf in the bow wave, getting an exhilarating free ride. The right combination of boat speed and playful dolphins can result in hours of fun for dolphins and people alike!
But the playfulness doesn't end there. Sometimes the dolphins even enjoy swimming with people. Although we are slow and cumbersome in the water, the dolphins swim around us, seemingly making fun of our limited swimming abilities. It's a good thing that they do stick around, because otherwise it would be impossible to shoot footage like this. Dolphins are too fast to keep up with underwater, even using dive scooters.
Playfulness is rare in the animal world. Most animals in the oceans are more concerned about getting enough food to eat and keeping away from predators than with goofing off. But dolphins, like people, have developed to the point that they are able to acquire their basic survival needs with time to spare everyday, giving them plenty of time for play.
One of the reasons why dolphins have so much spare time is that they can find food easily, and don't have to work too hard at it. Dolphins have a form of sonar called echolocation, which enables them to "see" for great distances underwater. This is accomplished by making clicking sounds which travel through the water and bounce off of distant objects. By listening carefully to the sounds bouncing back at them, the dolphins can detect objects which are too far away to be seen with their eyes, or are buried in the sand. Their favorite food is small fishes which live in the sand. Using their echolocation, the dolphins see right through the sand and hunt these fishes with great precision.
Echolocation is also how dolphins navigate. They see distant underwater terrain using sound as clearly as we see the above water terrain using our eyes. In an attempt to record the sound of the dolphins echolocation we set out in a small boat. To get a good recording, we need to get away from the noises made by the generator on the research vessel. Lowering a hydrophone into the water, we can clearly hear the sound of echolocation, even though the dolphins are hundreds of yards away.
But these are not the only sounds made by dolphins. When swimming with them, we frequently hear them make squeaks and whistles. Researchers have discovered that every dolphin has its own distinctive whistles, and that one dolphin may call to another by emulating its sound. It seems as if this system is used to call each other by name. Is this a form of language? Are the dolphins talking to each other? Nobody knows for sure, but many biologists believe that they are. It would make sense that these dolphins might talk to each other. Sometimes many of the same dolphins are seen together all of the time, suggesting that they may be friends, or relatives.
In fact, dolphins are social animals, meaning that they stick together, in groups. These groups, called pods, vary in size from two to sometimes over 100 dolphins, although it averages around 5 to 10.
We are swimming with Spotted Dolphins, but you may notice that not all of the dolphins are spotted, and some have more spots than others. Spotted Dolphins are actually born with no spots, like this one year old calf swimming with his mother. This calf won't begin to develop spots until he is about four years old. As he matures, he will develop a unique spot pattern. Like fingerprints, this pattern will give researchers a way to keep track of him. But as Spotted Dolphins age, their spot patterns grow and change, making it necessary to keep a photographic record of the changes every year if the dolphin is to be recognized later. Other markings, like scars, do not change much every year, and make some dolphins very easy to identify. This animal has two notches out of its dorsal fin. These markings are called permanent ID's and will probably remain with the dolphin its entire life, which may be over 30 years.
Because of tedious research by many dedicated individuals, we are beginning to understand more and more about dolphin societies every year. One such individual is Wayne Scott Smith, captain of our dive boat, the Dream Too. Captain Scott isn't a biologist, but he has been swimming with wild Spotted Dolphins in the Bahamas for many years, and he has grown to know many of the dolphins personally.
"When I first started swimming with these wild Spotted Dolphins up here, it started out as more of a friendship relationship. I didn't look at them as research animals...I didn't look at them as even to catalog them. I looked at them more as a friendly animal to interact with. And this is what really cemented the relationship together is that I didn't worry about all this research stuff and I worked at playing with them...simply being there and playing with these wild dolphins. As time has gone on, I've started to assemble the I.D. catalog, and the behavior video and started to work more into cataloging them, keeping track of them and doing informal research.
"In the identification catalog there are 105 [dolphins] that are named. Most of the names come from Bahamian islands or Bahamian rocks throughout the Bahamas. Some of them refer to major scars that they might have such as Sharkbait, Scarback, or Notcho. Out of the 105 individuals, there are 25 to 30 of them that I can recognize right off the bat. These are basically what I call the permanently identification marked dolphins. In other words, they have permanent markings such as the top of the dorsal fin missing, notches out of the back, things like this, that I know will stay with them all of their lives. It makes them easily recognizable whether you see them underwater or from topside. They become the ones that I'm going to be able to keep track of as the years go on."
While Captain Scott is learning about dolphins by studying them in the wild, other researchers work with semi-captive Bottle-nosed Dolphins at the Dolphin Research Center in Marathon Key, Florida. These dolphins seem to thrive on the interaction they get with humans, but most also go out and wander the ocean every once in a while too. Several of the dolphins here have invented a game called "Throw seaweed at the visitors" Although at first it just seems cute, it usually leaves visitors impressed by the dolphin's intelligence (and a little wet).
The question of intelligence leads researchers to wonder just how smart dolphins really are. We know that they can be taught tricks, but that doesn't necessarily indicate intelligence. The dolphin's brain is quite large in comparison to its body, and the Bottle-nosed Dolphin's brain is actually larger than a human brain. Many biologists believe that the large brain is needed for the complex processing of their echolocation signals. Others think that they are just plain smart.
One sure way to recognize intelligence is in social behavior. All higher animals, like monkeys, people, and dolphins, have a complex social system, and many are also playful.
"I think the dolphins understand that we are mammals. Mammals are kind of rare in the ocean...for them anyway. Dolphins don't get to see a whole lot of other mammals. So I think they recognize that we are mammals. They also recognize that we interact back with them, unlike a fish or a shark that would have a tendency to swim away, we give some sort of interaction back, whether its swimming with them, eye contact with them, or things like this. I think that's what initially grabbed their interest, the fact that we interact back with them, compared with the other animals they play with."
Although it may seem that dolphins do little more than play, they have another very important activity which occupies their time: flirting. Dolphins are very tactile and social. They show affection for each other by rubbing each other with their pectoral fins. When actual mating occurs, it is completed very quickly, with the two dolphins swimming belly-to-belly during intercourse. The male's penis is normally protected inside of his body, and can only be seen during copulation, when he has an erection. After 4 to 5 months, the female will begin to show outward signs of her pregnancy.
"This picture is of Selena and you can see that she is very pregnant. In fact, she probably went off and had her baby the same day this picture was taken."
The gestation period for Spotted dolphins is about 11 months. After the calf is born, it will stay with its mother for over two years, but is only really dependent on her milk for several months. Nonetheless, the playful, hyperactive youngster is probably quite a flipperfull for mom! Soon the calf will learn to catch its own food. But not until age 6 or 7 will the calf become sexually mature. Long before sexual maturity, the calf will engage in mock mating--basically practicing for the real thing. Female or male, by the time the calf is sexually mature, it will know exactly what to do.
All dolphins and whales in United States waters are protected by the marine mammal protection act of 1972. Other countries have enacted similar laws designed to protect marine mammals, many of which are endangered. Although Spotted Dolphins are not endangered, other equally intelligent and beautiful species are endangered and may need our help to survive. Learning about dolphins is one of the best ways to help them. Whether it's research at sea, or in captivity, the study of dolphins raises awareness and concern for this curious creature of myth and legend. But research also generates as many questions as it does answers. It is clear that we just don't know very much about these animals. Certainly, dolphins are intelligent and friendly. They have been respected and admired in many cultures, all over the world. And, they can be taught complex commands by human trainers. But if we learn to listen to dolphins and understand what they may be telling us, dolphins may, in fact, teach us a lot more than we have taught them.