I know that all common nouns in English are of a neuter gender (i.e. I should use the pronoun "it" with it).

Ship is an exception and should be adressed as "she".

The question is - what pronoun should I use when talking about animals?

In russian, every noun has its own gender
Медведь (Bear) - он
Белка (Squirrel) - она
Лошадь (Horse) - она
Жеребец (Stallion) - он
Кобыла (Mare) - она

Which nouns should I use?