Species vs. Species’s – Which is Correct?

“Species” is correct as the singular and plural noun for a group of related organisms. “Species’s” is also correct when it marks singular possession, meaning “belonging to one species,” although “species'” or “of the species” may sound smoother in formal writing. The apostrophe changes grammatical function, not the noun’s spelling.

Species or Species’s – Which is Correct?

Both species and species’s are valid, but they serve different grammatical purposes. Species is a noun that names one or more groups of related organisms. It has the same spelling in both singular and plural forms.

Species’s is the singular possessive form. It means “belonging to one species” or “associated with one species.” For example, “The species’s habitat is shrinking” refers to the habitat of one species. In formal or scientific writing, writers may prefer the species’ habitat or the habitat of the species for a smoother style, but species’s is grammatically possible.

The Best Trick to Remember the Difference

Use the apostrophe test: if you are naming an organism group, write species. If you can replace the phrase with “belonging to one species,” use species’s. For example, “Several species live here” names groups, while “The species’s range is limited” shows possession.

Word	Part of Speech	Meaning	Example
species	Noun	A biological group; singular or plural	This species lives in wetlands.
species’s	Singular possessive noun	Belonging to one species	The species’s population is declining.

How to Use Species

Species is a biological noun used for a group of organisms that share defining characteristics and can generally reproduce with one another. It is common in scientific, educational, environmental, and everyday language. The word can refer to one species or to multiple species because its singular and plural forms are identical.

When referring to a single group, use a singular verb: “This species is endangered.” When referring to more than one group, use a plural verb: “These species are endangered.” Demonstratives and context usually make the number clear.

Example 1: The blue whale is the largest known animal species.

Example 2: Several species of birds migrate through the region each autumn.

Example 3: Scientists discovered a previously unknown species in the rainforest.

What are the different forms of Species?

Species has an irregular-looking but unchanged plural. Both one group and multiple groups are written as species. Context, articles, demonstratives, and verbs show whether the word is singular or plural.

• Singular: one species, this species, the species is
• Plural: many species, these species, the species are
• Singular possessive: one species’s habitat
• Plural possessive: several species’ habitats

In some styles, species’ may also appear as a singular possessive because the noun already ends in -s. However, species’s clearly signals singular possession, while species’ most clearly signals possession by multiple species.

Etymology of the word Species

Species comes from the Latin word species, meaning “appearance,” “form,” or “kind.” It entered English through Old French and Middle English. Its biological meaning developed from the broader idea of a distinct type or kind of thing.

How to Use Species’s

Species’s is the singular possessive form of species. Use it when one species owns, contains, produces, or is associated with something. The apostrophe and s show that the following noun belongs to or relates to a single species.

Because species’s can look visually awkward, especially in technical writing, many editors choose alternatives such as the species’ genome or the genome of the species. Nevertheless, species’s is understandable and grammatically defensible when singular possession is intended.

Example 1: The species’s natural range extends across three mountain valleys.

Example 2: Researchers mapped the species’s genetic variation.

Example 3: The species’s survival depends on clean coastal water.

What are the different forms of Species’s?

Species’s is already a possessive form rather than a separate noun. It normally refers to one species. For possession by multiple species, use species’: “The species’ habitats overlap.” You can also avoid the possessive entirely with an of phrase: “the habitat of the species.”

Number	Possessive Form	Example
One species	species’s	The species’s nesting site
Multiple species	species’	The species’ nesting sites

Etymology of the word Species’s

Species’s is formed by adding the standard English singular possessive ending -‘s to species. The base noun ultimately comes from Latin species, meaning “kind,” “form,” or “appearance.” The possessive form is an English grammatical development, not a separate word inherited directly from Latin.

Related Concepts

Understanding number, possession, and agreement makes the difference between species and species’s much easier to recognize.

• Irregular plurals: Some nouns have the same spelling in the singular and plural, as with species, sheep, and deer. Context and verb agreement identify the number.
• Possessive nouns: Possessive forms show ownership or association. A singular noun generally takes -‘s, as in species’s habitat.
• Subject-verb agreement: “The species is” refers to one group, while “The species are” refers to multiple groups.
• Scientific terminology: In biology, species has a specific classification meaning, although ordinary language may use it more broadly to mean a type or kind.

Examples from Media and Literature

The word species appears frequently in scientific nonfiction, environmental journalism, fiction, and film because it describes biological diversity and classification.

• Charles Darwin’s On the Origin of Species: The title uses species in its plural sense to discuss the development and variation of living groups.
• Environmental news reports: Articles about conservation commonly describe an endangered species, an invasive species, or the discovery of a new species.
• Science fiction films: Stories such as Alien and Avatar use species to distinguish human beings from extraterrestrial or nonhuman life forms.
• Nature documentaries: Narration often contrasts one species with another while explaining habitat, behavior, and adaptation.
• Ecology textbooks: Phrases such as “keystone species” and “indicator species” show how the noun functions in formal scientific terminology.

Practice Exercises

Choose the correct word to complete each sentence: species or species’s.

1. The researchers identified a new ______ in the desert.
2. The ______ population has fallen sharply over the past decade.
3. Several ______ depend on the same wetland.
4. The scientists studied the ______ mating behavior.
5. This ______ is found only on the island.

Answer Key

1. species — It names one biological group.
2. species’s — It shows that the population belongs to one species.
3. species — It is plural after “several.”
4. species’s — It is the singular possessive form.
5. species — It names one group, and the singular verb “is” confirms the meaning.

Species Synonyms

Synonym	Definition
Kind	A general category or type of thing.
Type	A group sharing particular characteristics.
Variety	A particular form or subdivision of something.
Organism group	A biological grouping of related living organisms.

Species’s Synonyms

Synonym	Definition
Of the species	A formal phrase meaning associated with one species.
Belonging to the species	Describes something owned by or connected with one species.
The species’ own	An alternative emphasizing possession or association.
Associated with the species	A clear alternative for scientific or technical prose.

Frequently Asked Questions

Question 1: Is “species” singular or plural?
Species can be either singular or plural. Write “one species is” for a single group and “several species are” for multiple groups.

Question 2: Is “species’s” grammatically correct?
Yes. Species’s is the singular possessive form, meaning something belongs to or is associated with one species. Some style guides prefer species’ or of the species for stylistic reasons.

Question 3: Should I write “species’” or “species’s”?
Use species’s when you want to make singular possession unmistakable. Use species’ for plural possession, or when your preferred style guide permits it as a singular possessive. In formal writing, “of the species” is often the clearest alternative.

Conclusion

Species is the unchanged singular and plural noun, while species’s is its singular possessive form. Choose species when naming a biological group and species’s when describing something belonging to one group. Pro tip: In professional or scientific writing, check your style guide and use “of the species” when the possessive form could distract readers.