What is the difference between kind of and kinds of?

Can we say something like that:

What kinds of animals do you know? or only What kind of animals do you know?

In some sources(dictionaries) I found that the first option is not acceptable whereas in others it is acceptable and now I am confused.

http://oald8.oxfordlearnersdictionaries.com/dictionary/sort_1

When we should use kind of with plural nouns and when kinds of with plural forms?

thanks in advance

layla
layla1234What kinds of animals do you know? or only What kind of animals do you know?
No need to be confused, they are both fine. Which one you see is largely the choice of the author. There is seldom any difference in meaning.

I don't think I can give you any better general advice than you will find in the learner's dictionary you cite, it seems to be pretty good. If you have any additional specific questions please post them.
Kind of is used to refer to a single type.

eg. The rose is a kind of flower.

Kinds of is used to refer to many types within the same family.

eg. Rose, hibiscus and jasmine are different kinds of flowers.
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So what is the choice of the author?

If he says: What kinds of animals do you know ? What does he mean?

What kind of animals do you know? What does he mean?
If he says: "What kinds of animals do you know ?" he asks what are the types of animals you are familiar with.

What kind of animals do you know? What does he mean? As far as I know, this is gramatically incorrect. It should be " What kind of animal do you know?" This means "What is the single type of animal you are familiar with ?"