Outer Banks Dolphin Research: Just the Facts

Just the Facts - Bottlenose Dolphins

by Beth Carter

So...how did they get the name bottlenose? These dolphins have a short snout that curves like an old-fashioned bottle.

Bottlenose dolphins…

...are mammals.
...can grow from 6.5 feet to over 12 feet long. Males are longer and much heavier. Males can weigh up to 440 pounds.
...have smooth rubbery skin. It is 10–20 times thicker than our skin! They shed their outer layer of skin every two hours!
...have a thick layer of blubber under their skin. Blubber keeps them warm in cold water.
...have tails called flukes.
...have dorsal fins that are each different in appearance. Each dolphin’s dorsal fin has scratches or marks or a special shape. Scientists take pictures of the fins to identify the dolphins.
...have special whistles. Each dolphin makes up his whistle, called a signature whistle, when he or she is just two months old.
...make all kinds of noises, like creaks, clicks, moans, and whistles.
...strongest sense is the sense of hearing. They do not have a sense of smell!
...use echolocation, like bats do, to locate objects while they swim. Echo = sound, and Location = place. So echolocation means that dolphins use sounds to locate specific objects and places underwater.
...make sounds that travel from their melons (heads) to bounce off objects. The sounds return to “be heard” in fat found in dolphins’ lower jaw bones.
...on the North Carolina coast do not find prey with echolocation. They stay very quiet and listen for their prey. This is called passive listening.
...breathe air through a blowhole on top of their heads.
...can hold their breath for 12 minutes.
...can dive from 10-150 feet. Some can go up to 2000 feet deep, though that is unusual.
...sleep by shutting down half of their brains at a time. One half sleeps while the other half stays awake. This way, the dolphin swims and breathes and stays alert. Later, the other half goes to sleep! They sleep about 8 hours a day.
...eat fish, squid, and shrimp.
...have teeth that are cone-shaped. Their teeth are for grabbing fish, not chewing.
help each other hunt for prey.
...do not live in family groups. They live in groups that change.
...do not mate for life.
...have babies called calves. A mother nurses her calf for 18 months. The calf stays with the mom for 3-6 years. Males do not help with raising the calves.
...are very intelligent. They have large brains. The biggest part of their brains holds the auditory nerves, which help them with echolocation.
...ain threats are fishing practices by people, and pollution. Dolphins can get stuck in fishing nets. They drown if they cannot get to the surface to breathe.
...re protected by the Marine Mammal Protection Act of 1972. It is against the law to hurt a dolphin or change its behavior. Wild dolphins should not be fed.

Think About…

How can humans hurt dolphins? How can humans help dolphins?
What do you think is happening to dolphins that lived in the Gulf of Mexico near the oil spill? Can they swim away from it? What about the fish they prey upon?
What will happen if shrimp that the dolphins eat are contaminated with oil?
Is it good to capture dolphins and put them on display in a place like Sea World? What’s good about that practice? What is not good about that practice?
What are some of the similarities between dolphins and people? What are some differences?
What do all people and dolphins need to live?

About the author:

Beth Carter is a K-1 teacher at the Cape Fear Center for Inquiry in Wilmington, NC.

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