Riddles about animals

I have four legs. I am a pet. I hate cats. I bark.

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?

Why do birds fly south in the Fall?

I had no father, only a grandfather. I shall bear no sons, only daughters. What am I?

I hiss. I can be poisonous. I am long. I have a forked tongue. What am I?

I eat other animals. I have a big mouth. I am green. I live in the water. Who am I?

I sleep when you are awake, I am awake when you fall asleep. I can fly but no feathers to aid my flight. What am I?

I am alive without breath and cold as death. I am never thirsty but always drinking. What am I?

I am small. I can be scary. I have eight legs. I spin a web. What am I?

I plow and plow, but never sow. What am I?