The cetaceans are aquatic mammal animals that make up the order Cetacea . These living beings, which are characterized by their large size, have no later members, while the previous members became fins . Their bodies In addition, they end in a single horizontal fin.

In the upper sector of the head , cetaceans have nasal openings where they breathe. Through these openings they expel the air, which when condensed resembles a jet of water.
Cetaceans usually have no hair: a layer of grease Very thick allows them to withstand low temperatures. The vast majority of the eighties species of recognized cetaceans are marinas , although there are some species of dolphins that live in sweet water .
The largest animal that exists is a cetacean: the blue whale . These specimens usually weigh more than one hundred tons and have a length of about 25 meters. Due to the hunting , the population of blue whales declined for many years, until their protection began in the mid-1960s.
The Southern Right Whale , the glacial free whale and the greenland whale are other species of whale that belong to order of cetaceans.
The dolphins , the toninas , the killer whales , the belugas and the porpoises They are also cetaceans. All these animals they have characteristics in common and, in turn, multiple differences.
In addition to all the above about cetaceans, it is worth knowing another series of relevant aspects about cetaceans such as the following:
-The blue whale is considered to be the largest animal that has existed on planet Earth. And it is that she can reach 33 meters long, while the largest dinosaur known so far, the Dreadnoughtus schrani, was 26 meters.
-The aforementioned blue whale has the ability to eat between 6 and 8 tons of food per day.
-The tongue of that mentioned whale weighs the same as an elephant.
-The breeding of a blue whale comes to the world with a size of 7 meters in length. Going fat daily about 90 kilos.
-The fin whale can reach up to 45 kilometers per hour and can dive up to 200 meters deep in search of food. Dolphins, meanwhile, are faster because they can reach 54 kilometers per hour.
-The dolphins, under water, are able to detect all kinds of threats and even objects with a sonar system very similar to that possessed by bats. It is what is known as echolocation.
-The so-called screw dolphins have the ability to jump out of the water up to 7 meters high.
-The capacity of a whale's stomach is really impressive. Thus, if that of a cow is 209 liters, that of the mentioned cetacean reaches 760 liters.
It should be noted that cetaceans are predators They feed on fish, cephalopods, plankton and, in the case of killer whales, other marine mammals. The main threat to the subsistence of cetaceans, on the other hand, is the human being .