Yawning is an involuntary deep breath. As you know, it makes up for the lack of oxygen and gives a sense of freshness. Man tries to yawn quietly so as not to seem sleepy or bored. Animals are not bound by etiquette and always yawn when they need it. And the need to yawn they are not always the same as in humans.
It is noted, for example, that predatory cats of the African plains before the hunt often stretch out. When night falls and, accordingly, improves the appetite, nervous animals, moving fitfully and... yawn. This is due to the need to capture more air into the lungs, to increase the level of oxygen in the blood. The heart pumps enriched blood to all parts of the body, thereby providing them with the energy needed for the rapid surge in the future of hunting.
And not only lions, even fish yawn before to swim faster.
They can yawn and when something worried, you see an enemy or food - in short, in all situations where you need to react quickly.
But some animals yawn, not only in the conventional sense, but for quite different reasons. And they have a pretty amusing. Monkeys, for example, use yawn as the possibility of something to say. Outdoor yawn mouth coupled with bared teeth mean a warning for male opponent or alleged predator - "don't come!"
Rats yawn when hungry.
Expressive yawning Hippo. This massive creation can open its mouth impossibly wide, forming an angle of 150 degrees. This helps old male-the hippopotamus is not only to show everyone in the pond who's the boss, but has one quite intimate detail.
The fact that the jaws of the beast works like the exhaust emitted into the air waste gases. Famous yawning Hippo, misuse visitors of the zoo, is a gaseous "waste" (and "production" in the Hippo is considerable, which are three large and eleven small stomach, extracts from the rough raw juices of life). Fortunately, begemotova no smelly gases and therefore does not frighten people.
Some animals yawn to show what they have big teeth.
However, none of the theories can't explain why yawn fish, turtles, crocodiles. It is hard to imagine that some Karasik wants to announce that he was tired.