Here's why:
* Gorilla is a specific type of animal.
* Antonyms usually describe opposites within the same conceptual category.
However, you could consider some alternative ways to express the opposite idea:
* Human: If you're talking about comparing gorillas to humans, "human" could be considered an opposite.
* Small primate: If you're focusing on size, a smaller primate like a monkey could be seen as an opposite.
* Non-primate: If you're thinking of contrasting gorillas with other animals, any non-primate animal (like a dog, cat, or bird) could be considered an opposite.
It really depends on the context of what you're trying to express.