Why animals in general have two nostrils

This is on the soso question, and I have seen that the writing is quite complicated.

It can be roughly summed up as the principle of alternation, and the principle of symmetry.

Higher animals are symmetrical, and symmetrical representatives have good genes.

Most of the time, the other two nostrils do not work at the same time, but alternately, but the humans themselves are not aware of it.

What animal has two holes on both sides of its nose? That's a good question. The answer is mammals.

Mammals have two small holes in their noses, and the flame splitters are called "left airways" and "right airways". They are formed by costal cartilage, mucous membranes, tricular blood vessels, neurons, and in most cases small ducts that are joined together.

Typically, the left airway leads to the heart, while the right airway leads to the stomach or large intestine. So, when you exhale, it will flow first through the airway on the left side and then through the airway on the right. And when you breathe in fresh air, it is first inhaled into the left airway by the ascending stage, and then flows through the right airway to choke on the chest.

Also, don't forget that most of the olfactory nerves are concentrated there – thus allowing them to sense the chemistry around them and transmit them to the brain to act or think accordingly.

In short, the existence of the left and right airways has led us to understand that most animals have more complex theosystem-relationships in addition to trembling and inhalingMost importantly, it allows the animal to have more physiology than a "human", giving the animal the opportunity to adjust to the dangerous conditions around it, such as natural extremes.

Elephants, anteaters, echinois.

Elephants are mammals, proboscidae, and elephantidae. It is also the largest mammal on land. He likes to live in the jungle and grassland, and is a staunch vegetarian.

The lifespan is long, up to eighty years. The pregnancy period is also long, up to 22 months, and one child is born in one child. There are three species of African elephants, African forest elephants and Asian elephants, with the African elephant being larger and the Asian elephant being relatively smaller.

African elephants are irritable and can attack other animals, while Asian elephants have a milder temperament. African elephants have tusks for both males and females, while Asian elephants have tusks only for male elephants. Because ivory has been regarded as a precious item since ancient times, and there are many collectors, the elephant population has declined dramatically, and although there have been many international laws banning the ivory trade and publicly burning ivory products, poaching is still prohibited for profit.

There is no conclusive evidence as to whether the legendary elephant graveyard actually exists.

Anteater anteater (scientific name: myrmecophagidae), a mammal, a family of the order Trichodae, only 3 genera and 4 species, distributed in the Americas. snout elongated, mouth tubular shaped; The tongue is retractable and mucus-rich, suitable for licking insects; The ears are small and round; The forelimbs are strong, the third finger has a particularly well-developed and sickle-shaped hook claw, and the hind limbs 4 5 toes also have claws.

The skull is elongated and fragile, toothless. Eat ants, termites and other insects. Pygmy anteaters are arboreal and often go to the ground.

The large anteater mainly inhabits humid forests and swamps, is active during the day or night, and is good at swimming; Small anteaters can have their tails curled, and the black spots on their throats and shoulders form collars on their necks, and they hide in dense forests or tree holes during the day, and come out to forage at night, and often use their forelimb claws to destroy ant nests. It mainly inhabits Central and South America, and reaches south to the tropical forests of Argentina.

Echidna is one of the most primitive mammals, a collective name for the Tachyglossidae family.

It resembles a hedgehog in appearance, has a very short tail and a body length of about 40 to 50 cm. Some of the body hair becomes hard spines, and there are fine hairs between the spines and on the ventral surface. The tip of the snout is short and straight, with a sheath on the outside.

It has no teeth, and its tongue is slender like a thread, with mucus on it, and can stick out of the mouth to catch food. The legs are short, with 5 claws on each of the front and rear limbs, which are long and sharp, suitable for digging.

It resembles a mole, is nocturnal, burrowing, and feeds on termites, ants, and other insects.

1] Oviparous, usually laying only 1 egg at a time. During the reproductive period, the ventral surface of the female animal ** folds into a sac, that is, a temporary nursery bag. The eggs hatch in the bag for about 7-10 days. The breast area is located inside the pouch.

There is hibernation. It is found only in Australia and New Guinea.

Why do most animals have two nostrils?

Do the two nostrils also have a similar effect? Although we have two nostrils, we actually use one nostril to breathe in each version. The turbinate mucosa of the nostrils contains erectile tissue made up of blood vessels and connective tissue, and the erectile tissue of the two nostrils contracts and expands alternately, allowing one nostril to be unobstructed and the other to be blocked, which cycles every few hours.

I think the ancestors of these animals are the same, and they all happened to retain the traits of both nostrils in the course of later evolution. In the process of evolution, there may be an individual with a nostril, but a nostril is not conducive to the survival of the organism. So all the creatures that have one nostril will appear one dead and one will have two nostrils.