Full Idea
The essential properties of a thing will typically depend upon what category of thing it is, and perhaps also on some more particular facts about the thing itself.
Gist of Idea
Essential properties depend on a category, and perhaps also on particular facts
Source
Graeme Forbes (The Metaphysics of Modality [1985], 5.1)
Book Reference
Forbes,Graeme: 'The Metaphysics of Modality' [OUP 1985], p.97
A Reaction
I see no way of dispensing with the second requirement, in the cases of complex entities like animals. If all samples are the same, then of course we can define a sample's essence through its kind, but not if samples differ in any way.