"The hare is an animal and a mammal"

[KeithJones949537]

So would it be wrong to use the indefinite article before ζωο in this sentence?

[ChrysiCh.]

No, it's not wrong if you say "Ο λαγός είναι ένα ζώο" or "Ο λαγός είναι ένα θηλαστικό", but if you say "Ο λαγός είναι ένα ζώο και ένα θηλαστικό" it sounds unnatural and weird.

[GarrettDiment]

Yes, why is there no equivalent to "an" before "animal" and "a" before mammal here? Does Greek not need these. and if so, when?

[troll1995]

As a rule of thumb, the indefinite article in Greek can be omitted if there cannot be more than one of the following noun/attribute. A hare cannot be more than one animals or mammals, so the indefinite article can be omitted. But in a sentence like "I want a pair of shoes=Θέλω ένα ζευγάρι παπούτσια" it cannot be omitted because you may want more than one pair of shoes.

[aaronxiii]

Why is there no ενα?

[Stergi3]

There is logical mistake here. Because the category animal includes the category mammal. It would be correct if it was in the form: Ο λαγός είναι ζώο και μάλιστα θηλαστικό, that μάλιστα specifies the kind of the animal.

[amyxz]

Ο λαγός είναι ζώο (θηλαστικό, τετράποδο).