Amazing Underwater Dolphins

Dolphins are small-toothed cetaceans easily recognizable by their curved mouths, which give them a permanent “smile.” There are 36 dolphin species, found in every ocean. Most dolphins are marine and live in the ocean or brackish waters along coastlines. There are a few species, however, like the South Asian river dolphin and the Amazon river dolphin, or boto, that live in freshwater streams and rivers.

The largest dolphin, the orca, can grow to be over 30 feet long. The smallest, the Maui dolphin, is just five feet long.

Dolphins feed chiefly on fish and squid, which they track using echolocation, a built-in sonar that bounces sound waves off prey and reveals information like its location, size, and shape. An echolocating bottlenose dolphin can make up to a thousand clicking noises per second.

Behavior and reproduction

Living in pods that can number a dozen or more, dolphins are intensely social mammals that communicatewith squeaks, whistles, and clicks. Whether dolphins have language, as humans do, is a topic that scientists have debated for decades.

As mammals, they have warm blood and nurse...