Answer:
20 animals.
Explanation:
Sparkles the unicorn is eating an apple, when a chango removes the apple from its mouth and bites it. We already have 2 animals in the forest: the unicorn and the monkey.
Then, the unicorn realizes that 18 pairs of eyes are watching the monkey. That gives us another 18 animals (considering everyone has 2 eyes).
so, in total we have 20 animals: (18 + unicorn + monkey) = 20 animals.