Hahaha I am vegan but I do not see meat-eaters as evil, just misguided ;) I like your profile pic by the way! A very good album from a great band!
The adjective has to agree with the noun in terms of the gender. "Zwierzę" is neuter, so must the adjective be.
Zle has several meanings, such as bad, nasty, angry, and, yes, evil. The sentence could have been translated to something more likely than saying the animal is evil.
Luckily duolingo is quite free in what translations it accepts for zły. I generally use bad/evil/angry interchangeably, or whatever makes sense in the context, on duolingo.
Exactly... I typed "mean", which was rejected. The way I see it, a mean animal or an angry animal makes more sense than "bad" or "evil". You can say that about a person, but not an animal.
Well, the thing is if the sentence makes sense in Polish ;) And I'm afraid that all the sentences with "zły" are, nomen omen, bad. It's too early to introduce this word, it's not that easy in use.
"mean" can translate to "niemiły", "wredny", things like that.
We very seldom accept such changes from singular to plural, but this is rather in sentences like "A tiger is an animal/Tigers are animals", which are without a doubt universal truths. I don't see a justification for such a switch here.