Singular is "Animal", and the plural is "Animais", right?
Yes, most words ending in "L" changes to "IS" in plural. (If it ends in "IL", there is no double "I")
O animal is always masculine even if referencing a female animal? It wouldn't be "A animal"?
Yes, the word animal is always masculine.
Os animals comem
Wouldnt it be Os animais comem ?