Dolphins in The River and Dolphins in The Ocean
As we know so far, most dolphins are friendly animals, perhaps because dolphins are types of intelligent animal. The size of dolphin's brain according to scientists is largest if compare with some species of whales (fin whale and sperm whale). There are some species of dolphins that lives in the river and some of them live in the ocean. Let’s take a look furthers the difference between dolphins that lives in the river and dolphins that lives in the ocean. But first, let find out about the types of dolphins and their habitat.
All dolphins, either river dolphins (dolphins that live in the river) or oceanic dolphins (dolphins that live in the ocean) are toothed whales. Both river dolphins and oceanic dolphins belong to sub-order odontocetes, the order of cetacean. Although dolphin's size usually smaller than other types of cetacean species such as humpback whales, some species of dolphins are quite large and can attain lengths over 20 feet.
There is species from the order of cetacean that have similarity with dolphin. The species is called porpoises. Porpoises are belonging to family Phocoenidae. The differences between dolphins and porpoises are dolphin have distinct beak while porpoises are not. Sizes of porpoises are smaller than any other oceanic dolphins. Some fishermen preferred to call porpoise for both dolphins and porpoises but some preferred to call dolphins to all type of dolphins and porpoises. Because some types of dolphins have large size, these large size dolphins even also called whales. For example, killer whale and orca. Porpoises and most various types of dolphins are more commonly found in the ocean. All porpoises habitat is in the ocean as well as certain type of dolphins and large size dolphins such as the killer whale. Porpoises and most various type of dolphins that live in the ocean called oceanic dolphins.
Yes, the blue whale is the largest living creatures on earth until now. The blue whale is the largest mammal ever recorded. The size of blue whale is average about 80 feet (25 meters)s long, with weigh about 120 tons or 109 tonnes. The size of blue whale is even bigger than dinosaurs that ever dominated the Earth.
There are 36 species of dolphins that has been found so far. Both, had habitat in the rivers and in the ocean. There are 32 oceanic dolphins and only 4 types of river dolphins ever found. Now let’s take a look at the difference between dolphins in the river (river dolphins) and dolphins in the Ocean (oceanic dolphins). Oceanic dolphins are belonging to super family Delphinoidea while river dolphins are belonging to super family Platanistoidea. River dolphins have poor eye sightings than oceanic dolphins because mostly they live in turbid water in the river. River dolphins are not active like oceanic dolphins and they have longer snouts than oceanic dolphins.
Type of dolphins in certain areas, either in the river or in the ocean depends on their environments such as food and temperature. The most common oceanic dolphins are Bottlenose Dolphin. We can recognize in Bottlenose Dolphin's shape because this type of dolphin is the common dolphins we often see, it can be in water parks, movies, sticker, or logo. It is because Bottlenose Dolphin is the type of dolphins that used to make a friend with human. Due to the largest scales of the ocean, oceanic dolphins like bottlenose dolphins can migrate, they usually migrate once every year. So they can live not only in one habitat like river dolphins but in certain places of the ocean. Because oceanic dolphins are the largest population on Earth, they have various types, not only Bottlenose Dolphins. Beside porpoises, there are certain species of whales are included in Dolphin’s family such as false killer whale, killer whale, long-finned pilot whales, short-finned pilot whales, pygmy killer whale and melon-headed whales.
Unlike oceanic dolphins as mention above, there are only 4 types of river dolphins on earth. They live in 4 different rivers on the earth. Dolphins that lives in the river or freshwater, live in various types of rivers including in South America and Africa. The river dolphins that lives in the rivers are named like in the habitat where they live in the river; they are Indus River dolphin (Bhulan), Ganges River dolphin (Susu), Amazon River dolphins (Boto) and Chinese river dolphin (Baiji). However, there are some species of dolphins that can live both in the rivers and in the ocean. Because of that, these four types of river dolphins are called as true river dolphins. Some type of dolphins that can live in the rivers as well as in the ocean such as La Plata dolphins (Franciscana) that can be found in coastal Atlantic waters of southeastern South America and Tucuxi (Sotalia fluviatilis) that can also be found in the rivers of Amazon basins.
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