Dolphin

Overview
Adored by humans for their seemingly playful nature, dolphins are among the smartest creatures in the animal kingdom. Australian researchers in 2005 discovered that mothers in a group of Australian dolphins teach their daughters to use tools. They break sponges off reefs to protect their snouts while digging around the sea bottom for food.

Dolphins are social creatures that travel in large groups called pods. There are around 40 species of dolphins known today, found in the shallower waters of continental shelves almost the world over. Their sizes vary from about 4 feet weighing less than 100 pounds, like the Maui dolphin, all the way to 30 feet weighing several tons, like the orca – also known as the killer whale, perhaps better known as “Free Willy.”

Diet
Dolphins are carnivores. Fish and squid are mainstays on every dolphin diet, though some of the larger species occasionally dine on other small marine mammals. Dolphins are known to hunt their food through a method called “herding,” where an entire pod will surround a school of fish and individual dolphins will take turns swimming through the middle. “Coralling” is another technique dolphins use to rustle up food. Dolphins will chase and corner fish in shallower waters where it’s easier to catch and eat them.

Bottlenose dolphins will go so far as to drive fish to muddy banks where they capture their prey using a method called “strand feeding.” Another method involves dolphins stunning their prey by smacking the water with their fluke.

Anatomy
Though they have fins and flippers, dolphins are not fish. They’re mammals, warm-blooded and dependent on oxygen. Their bodies are wide in the middle but taper at both ends making them extremely fast swimmers.

To help with navigation, dolphins – like bats and whales- echolocate. Located at the center of the forehead is the melon which assists with echolocation, in which the animal emits a noise and listens for the echo response that bounces off topography and other animals. Additionally, dolphins have acute eye sight both above and below water.

Dolphins, along with their cousins, whales and porpoises, are thought to be descendents of terrestrial creatures that entered the water 50 million years ago. Dolphins as we know them today did not appear in the oceans until about 10 million years ago.

Dolphins are thought to be the only organism other than humans that mates for pleasure in addition to procreation.

Threats
The biggest threat dolphins face is the incidental catch by commercial fishermen. Even though the Marine Mammal Protection Act is supposed to protect marine mammals, more than 1,000 dolphins and porpoises were harmed or killed by commercial fishing in the United States in 2005.

Dolphins are also under pressure from Japanese fishing fleets, which every year around October hit the high seas and herd pods into killing coves using loud noise. Despite worldwide opposition, some 20,000 dolphins are captured and slaughtered or sold into captivity annually with Japan citing consumer demand and scientific research as justification for the atrocity.