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206

common dolphin

OLogy Series
animal
card
206

common dolphin

OLogy Series
animal

With their white bellies and dark backs, dolphins can be found jumping above the water, swimming alongside fishing ships, or riding the waves of large whales. Dolphins are playful, intelligent, and very fast swimmers. They often work together to herd fish into tight balls, making them easy prey. They whistle, click, and squeak to communicate with each other, and to navigate through the ocean.

Talking Underwater
Like bats, dolphins rely mainly on echolocation to navigate and find prey. Echolocation is the ability to use the echoes of sound waves to locate distant objects. Dolphins emit a series of clicks from their nasal cavities, just below their blowholes. These clicks are sent out through the melon, a fatty structure in the dolphin's forehead. The melon helps focus the sound waves into a beam, directing them forward. The sound waves bounce off objects in the ocean, such as fish, obstacles, and other dolphins. The returning echoes travel through a fat-filled cavity in the dolphin's lower jaw to the inner ear. Using echolocation, a dolphin can tell the size, distance, speed, and even the shape of distant objects. This ability is particularly helpful at night or in murky waters.

Dolphin breathe through:

a blowhole at the top of its head

its mouth

gills

Are you right?

Correct!

A dolphin is a mammal, so it has lungs and breathes air. Dolphins must surface to get air. A dolphin breathes through a blowhole at the top of its head. When a dolphin dives under the water, it closes the blowhole to keep water out.

One of the best ways to tell a dolphin from a porpoise is by looking at its:

tail

color

teeth

Are you right?

Correct!

Dolphins have long, cone-shaped teeth, while porpoises have short, flat teeth. A dolphin uses its strong teeth to catch prey, not to chew. (Dolphins swallow their food whole.)

Dolphins tend to travel alone or in pairs.

Fact
or
Fiction
?

Fiction

Dolphins are very social, swimming in large schools or "pods." Sometimes hundreds or even thousands of dolphins are found swimming together.

Dolphins are related to whales.

Fact
or
Fiction
?

Fact

Dolphins and whales are cetaceans, a group of marine mammals. While whales have two blowholes, dolphins have only one.

common dolphin
Size: up to eight feet long
Weight: 250 pounds
Habitat: tropical and temperate oceans around the world
Diet: fish and squid
Characteristics: sleek body, long snout, dark tail,
flippers, and dorsal fin
Threats: fishing nets, pollution, hunting, human disturbance

Image credits: courtesy of Golden State Images.