Animals spawn regardless of block type via creating a new world

When I created the seed "FREE PLAY MODE!!!", animals "spawned" on sand;grass only,you know.

What I expected to happen was...:
It was a new world! How did I expect anything other than a good seed?

What actually happened was...:
Incorrect spawn specifications.

Steps to Reproduce:
1. Make the seed:
2. FREE PLAY MODE!!!
3. Make it survival and generate.