I'd like to know what option to use, specifically when referring to a species by its scientific name.

  • 1
    Definitely which. Who would be used of a pet, or an animal being considered as an individual. Jan 8, 2020 at 11:40

1 Answer 1


As a general rule, "who" should be used for people. "Which" is used for things. With animals, it depends on context. Animals are often anthropomorphised in literature, and also in daily life (especially pets), and so may be referred to in the same way as a person.

Some examples in media referring to a specific animal by its species, not by its name, but using "who" include:

  • The Cat Who Came In From The Cold (2007 book)
  • The Dog Who Saved Christmas (2009 movie)

When speaking about animals in a broader sense, you would not use "who". For example "people who live in cities" suggests that people choose to live there, whereas "penguins which live in Antarctica" did not make a choice to live there.

An alternative is to use "that", which can be used for either people or things, for example:

Penguins that live in colder areas eat fish, squid and krill.

  • 2
    Yes, definitely use “which” at the species level. But anthropomorphism of individual known and often named animals (pets, livestock and even wildlife) is at least as common in everyday life as it is in literature and other media. For example, in my house looking out the window into the front yard at a wallaby, I say to my wife, “Who’s that drinking from the water bowl? I think it’s that old male back again.” Jan 8, 2020 at 14:08

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