Dolphins use their blowholes to breathe air and to 'talk'

"How do dolphins breaths underwater?" asked Jenny Williams, 8, a third-grader at Townline Elementary School in Vernon Hills.

It's easy to mistake a dolphin for a fish. They live in oceans, they have fins, they eat tiny shrimp and they sleep in water.

Dolphins actually are warm-blooded mammals, just like you and me. They give birth to live babies and they nurse their young.

Fish breathe by taking oxygen out of the water through their gills. Dolphins gulp air through a giant hole on the top of their heads. Each time they need to catch a breath they have to burst through the water's surface.

"Dolphins are air breathing mammals just like dogs, horses and even people," said Ken Ramirez, Shedd Aquarium vice president of animal collections and training. "They cannot breathe underwater. Dolphins have a hole on top of their head, called a blowhole, which is like our nose, except on top of their head. When they need a breath of air they must come to the surface of the water so that their blowhole can open and take in air."

Dolphin's lungs and muscles are designed to take the big gulps of air from the blowhole and store oxygen so the mammals to dive underwater for long periods of time and then shoot quickly to the surface for more air. As they surface, they expel air through their blowholes and then gulp in more air so they can return to the ocean's depths.

Dolphins are playful animals and live in pods with their mothers, aunts and grandmothers. Around age 5, male dolphins take off to create their own pods.

Dolphins can doze and breathe at the same time. When it's time to take a snooze, half their brain goes to sleep while the other half remains alert. This way dolphins can remain somewhat conscious and continue to breathe. Dolphins also can sleep at the water's surface so their blowhole can reach air, and they can swim very slowly and catch a breathe every once in a while during a nap. These sleep periods occur a few times each day.

Aside from breathing, the blowhole helps dolphins to "talk." When air passes through muscles inside the blowhole, a dolphin can whistle or squawk and communicate with its pod members.

It'll be a few more months before the Shedd Aquarium's Pacific white-sided dolphins will be back home in Chicago. While workers are cleaning and improving the exhibit tanks and visitor areas at the Shedd Aquarium's Oceanarium, the dolphins and other marine mammals are on a mini vacation in Mystic, Conn.

Get updates online at http://interactive.sheddaquarium.org/web_diaries.

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