Surprisingly dolphins arent fish! A dolphin is a mammal. Like every mammal the dolphin is warm blooded, isnt born in eggs, and breathes air. A dolphin usually breathes once or twice a minute. A dolphin can hold its breath no longer than seven minutes but only if it is an emergency. Dolphins do have a tiny bit of hair! The only place there is hair is right next to the blowhole. Dolphins have blubber instead of fur. Blubber gives a dolphin their streamline shape. Blubber also is a cover that holds in heat. Dolphins teeth are usually made for grasping not chewing. If a dolphin needs to make its food into smaller pieces, it will grasp its food and throw it against the water. This makes it easier to eat the food.
There are 45 different types of dolphins. Some dolphins live in oceans and other types live in rivers. A trainer can sometimes tell the difference between each dolphin by their back fin. The bottlenosed dolphin is the type of dolphin most known. Dolphins are related to many other mammals in the ocean. The killer whale is the biggest dolphin!
A dolphins average life span is probably 20 years or less; eventhough, dolphins have lived as long as 48 years. We can tell how old a dolphin is by looking at its teeth. Each year it grows a new layer of tissue on its teeth. When a dolphin dies, its teeth can be cut to see how old the dolphin was, like the rings on a tree.
Dolphins die in various ways. They can get an infection, have breathing problems, or get heart disease. They can be killed by predators such as sharks or killer whales. Sometimes people kill dolphins on purpose. They use the dolphin for meat, leather, and oil. Human pollution also kills dolphins. They are also caught in fishing nets when people try to catch tuna fish.
A baby dolphin is called a calf. It takes 12 months until the mother dolphin gives birth. A female dolphin usually gives birth every 3 years, but they can have a calf every 2 years. Most calves are born May through July when the water temperature can reach 85 degrees Fahrenheit.
When a calf is born it is about 42 to 52 inches long and weighs about 44 pounds. Its dorsal fin and tail flukes are very flexible, but as the calf gets older both of these get stiffer. When calves are born, they are born with creases and stripes from how they were folded in their mothers womb. A womb is a place where the calf is kept.
An "auntie" dolphin helps the mother with the calf. The auntie can be male or female. It is the only other dolphin allowed near the calf. A calf is born tail first so it will not breathe the water. Dolphins give birth underwater and also nurse underwater. Newborn calves can see when they are born. They can also swim when they are born.
A calf starts to nurse within six hours of birth. She nurses as often as four times per hour. Each nursing session lasts only about five to ten seconds. In the first year it may gain 165 pounds and 2 feet in length. A calf stops nursing at 18 months. At 3-4 months old the calf gets teeth and begins to eat fish. When calves are only a few days old they can vocalize (make sounds).
Calves stay close to their moms. They swim along with their mother in her "slip stream". This is the water current that the mother makes when she swims and helps keep them together. When calves leave their mothers they keep in touch like we do. They go separate ways, but they come back and visit.
Calves stop drinking their mothers milk at 6 months of age. That is when they start eating fish. Dolphins eat shrimp, fish, and crustaceans. Adult bottlenosed dolphins eat about 4% to 5% of their body weight a day. A nursing mother eats 8% a day. Dolphins swallow fish whole and dont chew. If they need smaller pieces they rub them on the ocean floor or surface. They swallow fish head first so the fish's spines dont catch the dolphins throat.
Here are some ways they catch their food. In open waters dolphins gather together and circle around a school of fish and squish the fish into a ball. The dolphins take turns swimming into the school of fish and eat them. They sometimes use their tail flukes to stun the fish. Another way is to trap the fish at shore where fish can not usually survive. This is because dolphins breathe air and fish dont. If dolphins want to eat large fish they hit them out of the water with their tail flukes and then eat the stunned fish.
Dolphins use whistles and other sounds to communicate. Dolphins send out sounds to find food. The sounds bounce back from whatever they hit, and the dolphins can tell what it is. This is called echolocation. Humans cannot hear it. Echolocation can be used to see better under water, because under water color is really dark and dull.
Dolphins have nasal sacs inside their skull. They make noise by shifting air back and forth between their nasal sacs. We can make this kind of noise everytime we let air out of a balloon.
Dolphins communicate to locate food and to speak to each other. They have friends to help protect themselves from danger such as sharks. Dolphins lose their sonar system when they are put into tanks for many years. This is because they become deaf from their own echolocation. We do know that dolphins communicate to each other, but there are still questions if they communicate with people or if they are just trained. We know they are very friendly to people and very curious about us. Sometimes dolphins save humans from drowing by either pushing them to shore or pushing them up for air.
One of the most important things we have learned from dolphins is communication. The United States Navy uses echolocation for their submarines. They send sounds out that bounce back to where enemies and other things are. This is called Sonar. Sonar stands for SOund Navigation And Ranging. Dolphins echolocate better and faster than humans can. This is because they can hear higher pitched sounds and can make the noises much faster.
We are still studying dolphins because there is a lot to learn about communication.
Dolphins have adapted to their environment. They are able to survive because of these adaptations. A dolphins long nose helps them kill sharks. A fish's back fin goes side to side. A dolphins tail goes up and down to help it dive up to get air.
Dolphins need to save oxygen while they dive underwater. To do this, their bodies adapt in several ways. Their heart beats slower while diving, and their blood goes away from other parts of the body and goes to their heart, lungs, and brain. Another way it saves oxygen is in its muscles. The muscles have a special protein called myoglobin. Myoglobin stores oxygen.
Blubber (fat) helps the dolphin stay warm in cold water. The blubber also streamlines the body and helps it swim quickly and smoothly. The dolphin breathes from its blowhole and closes the blowhole before entering the water so water will not come in.
The dolphins only have baby teeth (or one set of teeth). They use their teeth to catch fish. Dolphins have large brains in relation to the size of their bodies. This shows that they are very smart. These are some of the ways the dolphin adapts to its environment.
ABL Kane Productions. Touched by a Dolphin. TV Special.
Behrens, June. Dolphins!. 1989.
Bender, Lionel. Whales and Dolphins. 1988.
Bright, Michael.Dolphins. 1985.
Encarta. Sonar. 1987.
Lauber, Patricia. The Friendly Dolphins. 1995.
Patent, Dorothy H. Dolphins and Porpoises. 1987.
Patent, Dorothy H. Looking at Dolphins and Porpoises. 1989.
Pringle, Laurence. Dolphin Man. 1995.
Serventy, Vincent. Whale and Dolphin. 1985.
Stonhouse, Bernard. A Closer Look At Whales and Dolphins. 1976.
Strachan, Elizabeth. A Closer Look at Whales and Dolphins. 1985.
World Wide Web. Seaworld/Busch Gardens. 1997.
A special thanks to...
Mr. Randy Reynolds
My mom, Mrs. F.
My dad, Mr. F.