Dolphin
From the Simple English Wikipedia, the free encyclopedia that anyone can change
Dolphins are mammals of the order Cetacea. They are animals that usually live in salt water, like the sea, but certain species can live 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. Due to how smart they are, which is almost as smart as a human, they have been used by the navy for jobs under the sea.
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[change] 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 saltwater estuaries and the ocean.
Water pollution and the loss of habitat are a threat to some dolphins, especially those living in rivers and estuaries.
[change] Taxonomy
[change] Oceanic dolphins (Delphinidae)
Some examples:
- Genus Delphinus
- Common Dolphin (Delphinus delphis)
- Genus Tursiops
- Bottlenose Dolphin (Tursiops truncatus)
- Genus Orcinus
- Orca (Orcinus orca)
[change] 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)
[change] 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. However, it is very firm, due to how much muscle they have. Dolphins use echolocation to find their food.
Dolphins do not sleep in a normal way. They have two sides of their brain, which they use to sleep. One side sleeps, while the other side stays awake. They will keep one eye open to watch for predators while they sleep.
