What am I riddles

I live in lakes and rivers. I eat fish and birds. I have four legs and a long tail. I have lots of pretty teeth. I am a...

I can be as thin as a picture frame but my insides have many things you can see. What am I?

I am a mother and a father, but have never given birth. I'm rarely still, but I never wander. What am I?

This is as light as a feather, yet no man can hold it for long. What am I?

I can run, but not walk. Thought is not far behind me. What am I?

I have lot of memories, but I own nothing. What am I?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

I can fly but I have no wings. I can cry but I have no eyes. Wherever I go, darkness follows me. What am I?

We can be boring, Or interesting. We can be long, Or short. We can have pictures, Or just words. Many love us, But many also hate us. What are we?

When you have me, you feel like sharing me. But, if you do share me, you don't have me. What am i?