Does animals have 6th sense.My dog many times comes to know certian visitor before callbell rings up.

Dogs operate on all their senses all the time (and that is where human psychic abilities begin).  The order of sensitivities in animals is:  horse, cat, dog, domestic animals, wild animals.

Pl eloberate in simple language.All living beings use their senses as per theie abilities & reqmt of environment.

Animals tend to live by their instincts.  This is a very sensitive side to animals and they all have it and can enhance it, just as human beings can develop their own sensitivities through practice and exercise.

I may be wrong but I don't attend the school of thought that thinks that animals have a "6th sense" .

As Spiritalk mentioned, they live by their instincts and yes they have senses that we , as humans, need to learn from them and how they use it so well for their survivals and many other worthy purposes.

They have psychic senses most definitely if that's what you meant VN Purohit, which enables them to do many things that we , as humans, can only do when for example our clairvoyance opens or clearaudience or other psychic senses for that matters.

In that sense (no pun intended  ) they are quite sensitive...

The cat ,for instance, is a remarquable animal in regards to psychic senses.

I would go with what Spiritalk as to us developing our psychic senses with Free will which is not the case for animals and humans having free will can use it for ill or for Good depending on one's intentions.

You will never witness a normal animal, however wild, use their abilities to cause deliberate harm or to use that for another function than to follow their instincts.