Best easy riddles for kids

I live in the ocean. I swim wherever I want. I sing to my family. I can breathe through a hole in the top of my head. I am a...

I am small and shy. I have eight legs. I eat bugs. I catch them in my web. I am a...

I live in a house. Each Halloween I stand in a jack-o-lantern and get shorter as I grow old. What Am I?

What comes down but never goes up?