||8 to 10 feet
250 to 600 pounds
||fish, crustaceans, and squid
||fish, such as herring and capelin, and squid
||the Atlantic coast from Virginia to Florida and into the Gulf of Mexico
||primarily along coasts in temperate and tropical waters
There is a lot to like about dolphins! They leap dramatically out of the water and re-enter with a satisfying splash. They make endearing squeaks and click sounds. Many of their fascinating behaviors, performed during presentations at zoos and aquariums all over the world, are a reflection of their natural behaviors in the wild. But even with their great popularity, there are still a lot of things most people do not know about dolphins.
What dolphins are
Dolphins are mammals (not fish!), although they do not really resemble the furry, land varieties we are most familiar with, like dogs, tigers, rabbits, people, etc. But dolphins meet all the requirements to be a mammal—they are warm—blooded, they produce milk to nourish their young, and they have hair. Hair? Where? Dolphins have hair for a few months after they are born, then they lose it for good.
Life in the water
Part of the reason that aquatic mammals like dolphins look so different from their land-mammal relatives is that life in the ocean presents different challenges for survival than life on land.
Dolphins are well adapted to the ocean. They have a smooth, streamlined body for easy movement through water. They move their flat tails, called flukes, up and down to propel themselves. Their pectoral (side) fins do the steering. The dorsal fin on top provides stability as the dolphin cuts through the ocean at up to 20 miles per hour.
Dolphins also have a special kind of camouflage that works well in water, protecting them from predators. Their bodies are dark gray on top, and their sides are lighter gray. Their belly is the lightest of all, usually white or faint pink. When seen from above, dolphins blend in with the darker depths of the ocean. From below, their light underside matches the sky.
Bottlenose dolphins are social animals, living in groups throughout their lives. The groups may fluctuate in size, from a pair of dolphins to more than fifteen. The group’s make-up changes, too. For example, mother dolphins will form groups with other female dolphins. Together, the females share the duties of raising their young. Sometimes juvenile dolphins get together, and it is in these groups that young dolphins learn the rules of dolphin society.
Catching fish is best accomplished in groups, too. Some members of a group will drive fish towards shore and catch them, while other dolphins hang back to prevent fish from making a dash for open sea. By cooperating, individual dolphins increase their chance of getting something to eat.
Whistle while you fish
As social animals, dolphins need to communicate with each other in order to hunt efficiently, raise their young, and guard against predators. Because it travels through water so readily, sound is the most important form of communication among dolphins. Each dolphin has his or her own unique "signature" whistle. These whistles announce a dolphin’s identity and location, even when he or she is well out of eyesight.
Signature whistles are produced in a dolphin’s forehead, or "melon." The melon is also the source of high-pitched sound waves that help dolphins catch fish. Dolphins find fish using "echolocation," bouncing click-like sounds off the fish and giving dolphins the exact location of their future meal.
Bottlenose dolphins at Brookfield Zoo
Seven Seas is home to a large group of bottlenose dolphins. CZS also supports research projects outside the zoo—way outside! In Sarasota, Florida, Dr. Randy Wells is in charge of a project that has been tracking the habits and health of wild dolphins for more than 40 years. Dr. Wells’ research in the natural laboratory of Sarasota Bay provides critical information about this species, including how water pollution affects dolphin health and the impact of boat traffic on dolphins.
Chicago Zoological Society/Brookfield Zoo is accredited by the Alliance of Marine Mammal Parks and Aquariums.