Dolphins are a small type of whale, in a group of mammals called cetaceans. They are warm-blooded creatures that almost always live in salt water, and can be found in nearly every ocean. Most live on the coast, remaining near to the shore, but some live out in the sea, away from land. Among the different types of dolphins are the Bottle-nosed dolphin, the Pilot whale, the White-sided dolphin, the Common dolphin, the Killer whale, and more.

The body structure of the dolphin is slim, enabling it to swin at incredible speeds. They are equipped with two powerful flippers, and usually a dorsal fin for balance, though not every type of dolphin has one. A tail fin, known as the fluke and is very strong indeed, is an important contributing force to any dolphin speeding through the waves (as they do). Their skin is smooth and rubbery, and they breathe with their lungs through a nostril on the top of their heads called the blowhole. The common dolphin, like humans, has a brain, esophagus, two shoulder blades, ribs, lungs, liver, stomach, intestines, kidneys, hip bone, and anus. They have what is called a melon in front on their skull, above their jaw, located where we might consider it to be the "forehead" of the dolphin. They also have enormous backbones.

Dolphins tend to mate in spring and early summer, during which the two genders, called (confusingly) bulls (for males) and cows (for females), bump heads and take part in other rituals. Pregnant dolphins are usually pregnant for 10 to 12 months, and upon finally giving birth, (having been helped by two other fellow dolphins in the procedure) help their newborn to the surface for the first breath of air.

Dolphins are one of the most intelligent species alive on our planet. They communicate with a wide variety of sounds, each of which may represent a different situation or emotion, such as danger or excitement. They also have incredible eyesight, hearing, and sense of touch, but they have almost no sense of taste or smell. However, they have another sense which is completely alien to us homo sapiens. Dolphins have a "natural sonar system" called echology, which is exactly what the name suggests. The dolphin releases a series of clicking and whistling sounds through the melon, which then rebound off from objects in front of it. The dolphin, upon hearing the echoes of these sounds, can sense the location and shape of everything in its path.

Dolphins are fantastic friends to our species. I have heard stories of packs of dolphins fighting off sharks from stranded sailors, and lost men at sea being towed to shore at no price. Out in the waves, they swim right up to waiting surfers, no fear, no discrimination, and maybe do a jump or a flip for them. I watch them body surf the incoming waves out in the Pacific, free from thoughts of getting revenge against the assholes who pollute their home and spear their relatives. They just want to be.

Information from the World Book Encyclopedia