Dolphin

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A Bottlenose Dolphin, the most well known type of dolphin.
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A Bottlenose Dolphin, the most well known type of dolphin.

Dolphins are mammals of the order Cetacea. They are animals that live in the water, in the sea or in rivers.

The name "dolphin" is used for oceanic dolphins and river dolphins. But oceanic dolphins and river dolphins are not directly related.

Their name, dolphin, comes from the Ancient Greek δελφίς (delphis) meaning "with a womb", because it was first thought to be a fish with a womb. It is now known to be very different from fish, because it breathes air and has warm blood, like all other mammals. They are believed to be very smart.

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[edit] Habitat

Oceanic dolphins are marine animals living in the sea. They live in all of the oceans.

Three of the four species of river dolphins live in fresh water rivers. The La Plata Dolphin lives in in saltwater estuaries and the ocean.

[edit] Taxonomy

[edit] Oceanic dolphins (Delphinidae)

Some examples:

  • Genus Delphinus
    • Common Dolphin (Delphinus delphis)
  • Genus Tursiops
    • Bottlenose Dolphin (Tursiops truncatus)
  • Genus Orcinus
    • Orca (Orcinus orca)

[edit] River dolphins

  • Amazon River Dolphin or Boto (Inia geoffrensis)
  • Chinese River Dolphin or Baiji (Lipotes vexillifer) (likely to be extinct)
  • La Plata Dolphin (Pontoporia blainvillei)
  • Ganges and Indus River Dolphin (Platanista gangetica)

[edit] Other

The brain of a dolphin is like a human brain in size and development. Dolphins have good eyesight. They can watch a thing in the water, and they can see colors, too. They can also see in dark places. Dolphins breathe air. Their nose on top of the head to be easy to breathe on the surface of the water. A dolphin's hearing is better than their sight.  There are some small holes behind the eyes, and they are the ears of a dolphin. Dolphins can hear a sound underwater. They can know the direction of the sound very well. The skin of a dolphin has no scales. It is soft and smooth.

Dolphins do not sleep in a norman way. Each of the two sides of their brain can be made to stop thinking. They let the right brain and the left brain be unused in turn to sleep.


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