Most "young earth creationists" (YECs) claim that there was no death in the world before the "fall of man" when Adam and Eve sinned. As a direct result of this concept, all creatures, including man were vegetarians.
This causes a number of questions that I have never heard a sufficient answer to.
- How do you explain that all plants are living things and would be killed the moment they were eaten and digested?
- Why would Adam and Eve and all the other animals have to eat at all if there was no death?
- What would have happened to them if they didn't eat before the "fall"?
- A number of creatures can only live from dead or decaying matter. When were they created?
- When were viruses created? Bacteria? Fungi?
- Why use would vipers and spiders have for venom? Heat sensing pits? Webs?
That's just to start, but I am sure we can go on and on should anyone have plausible answers.