6 facts prove the animal world will never stop us from being surprised

Do you know the sleeping otter always holds hands? It is just one of the many truths people are not thinking about about the animals in the natural world.

In the animal world there are so many mysteries and interesting things that we have not yet discovered. Or if it is discovered, not everyone knows about them.

1. sea and sleep "hands in hand"

Besides the petty appearance, the whole sea has a really easy behavior that makes every heart to melt, that is, holding hands while sleeping.

Oh, baby, are you .

However, they are not romantic or loving. The reason behind it is quite pragmatic: just to avoid being swept away by the waves while sleeping.

Normally, there will be dozens of otters holding hands, forming a solid raft when sleeping so that the waves won't cover the flood. In the case of sleeping alone, the otter will fix itself by seaweed.

2. Squirrels are animals that know . plant trees

The squirrel is very keen on the seeds and buried in the ground to store.

Everyone probably knows two sly squirrel Chip and Dale (Disney's "face-to-face" characters ) who love nuts. But in fact, in addition to chestnuts, red squirrels also like to eat many other nuts, like oak seeds. They were very keen on seeds and buried in the ground to store.

Unfortunately, if you compare red squirrel with goldfish, it is probably a nine or ten in terms of forgetting. Sometimes, the squirrels also forgot the location of hiding their "treasure", so that the seeds sprouted into new trees. Calculated each year, there are thousands of new trees are grown thanks to the forgetfulness of the squirrel.

3. Dolphins have their own names and they are aware of that

When they need to call an individual, they can copy the cry of that dolphin.

Dolphins are an extremely intelligent animal and live emotionally. In particular, they are considered to be the only animals that can call each other "names" without humanity.

A dolphin research team collected the sound of this animal for more than 10 years. They find that each dolphin emits a unique sound to inform them of their presence.

This sound can be detected at distances up to 20km depending on the depth of the sea level and the sound frequency. Especially when they need to call an individual, they can copy the cry of that dolphin. That proves that they can distinguish each other through a cry - just like how people call each other's names.

4. - The happiest animal in the world

This animal's face always grinned.

Quokka is a pocket rat with kanguru, living on some of Australia's small islands. This animal was dubbed the happiest animal in the world, not because of its happy life, but because its mouth always grinned.

This rat has a gentle, friendly personality and especially likes . selfie.

5. Penguins know . propose

Male penguins just need to pick up a beautiful stone to propose is okay.

The penguin has an extremely romantic "custom", that is, when finding the right mate, the male will open the marriage proposal.

Quite like humans? The only difference is that the male birds are very smart, not losing money to buy rings like humans. He just had to pick up a nice stone and give it to his children.

6. Cow has a close friend

Cows can be close to one or several individuals.

In a herd, cows can be close to one or several individuals. This has been proved by separating some close cows into a new herd. If they go alone, they will feel stressed, productivity drops. But if we go together, everything is not different.