What am I riddles

I have four legs. I live in Africa. I am big and grey. I live in the river. What am I?

I am not alive but I grow. I don't have lungs but I need air. What am I?

A slender body, a tiny eye, no matter what happens, I never cry. What am I?

I have a face like a tree and skin like the sea. A great beast I am, yet small vermin frighten me. What am I?

Give me food, and I will live. Give me water, and I will die. What am I?

It can't be seen, can't be felt, can't be heard and can't be smelt. It lies behind stars and under hills, and empty holes it fills. It comes first and follows after, ends life and kills laughter. What is it?

I eat, I live. I breathe, I live. I drink, I die. What am I?

I am pronounced as a one letter alphabet. I am written with three letters. I am complete with just two letters. I am double. I am blue I am black I am brown I am gray I am yellow and I am green. I can read from both ends. I appear the same every way! What am I?

I go in hard. I come out soft. You blow me hard. What am I?

I live in the ocean. I have eight legs, two big claws and a tail. My body has a hard shell. I eat anything I can find. I am a...