The word species’ is the singular possessive form of species. E.g., “The species’ defense mechanism protects it from predators.” Furthermore, species’ is also the plural possessive of species. E.g., “Many species’ habitats are under threat.” Also, species’s is not correct under any circumstances.
The word species is somewhat of an exception because the singular and plural forms are the same. Therefore, the singular and plural possessive forms are also the same. You form both possessives by adding an apostrophe to the end of the word species.
As shown in this chart:
| Singular | Species |
| Plural | Species |
| Singular possessive | Species’ |
| Plural possessive | Species’ |
Considering that the different versions of species are the same, it is the other words in the sentence that indicate whether you are referring to one species or more than one species.
Here are some examples so you can see the different forms in context:
- Singular: The Labrador is a widespread species of dog.
- Plural: The FCI recognizes more than 300 species of dog.
- Singular possessive: The newly discovered species’ survival mechanism is based on disguise.
- Plural possessive: Many species’ survival depends on protection efforts and funding.
In the singular possessive sentence, we have the singular verb is, so we know it is singular. In contrast, in the plural example, we have the word many, so we know it is a plural quantity of species.
You should keep reading the rest of the article to learn more about using the different forms of the word species.
Species’
The term species’ is the singular and plural possessive form of the word species. Therefore, the word species’ is quite different from most other words because the singular and plural forms are the same.
Therefore, you can use the possessive form, species’, to refer to things belonging to one or multiple species.
As shown in these examples:
- Singular: The dog species’ with the best temperament is the Border Collie.
- Plural: Most cat species’ natural instinct is to kill.
Furthermore, in formal writing, there is no variation of the possessive version of the word species.
Therefore, both the AP Stylebook and the Chicago Manual of Style use the version species’ as the singular and plural possessive.
Species’s
The word species’s is incorrect and is not a valid possessive form of species. Considering that species begins and ends in “s,” it would be quite awkward to add another “s.”
Therefore, species’ is both the singular and plural possessive version of species.
- Incorrect: The species’s main prey is mice and rodents.
- Correct: The species’ main prey is mice and rodents.