Plural of “species”

The plural of species is species.

Why

"Species" comes directly from Latin "species" (a seeing, appearance, or kind), and like "series," it entered English already ending in -s and never developed a separate plural form, giving an identical singular and plural spelling.

The word is central to biological taxonomy, where the exact number of species being discussed matters enormously for scientific precision, yet the noun itself carries no formal signal of that number at all — a biologist has to rely entirely on numerals, articles, and surrounding verbs ("one species is endangered" versus "several species are endangered") to convey something the grammar itself stays silent on. Taxonomic writing distinguishes "species" from higher classification ranks like "genus," "family," and "order," each of which pluralizes fully regularly ("genera" is actually the irregular Latin plural of genus, following yet another Latin pattern, while "family" and "order" pluralize with a simple regular -s), meaning "species" is genuinely the odd one out even within its own immediate scientific vocabulary.

Usage note

"Species" behaves grammatically like "series": never add -s, and let context, quantifiers, and verb agreement carry the distinction between one and many, since the noun form itself remains fixed regardless of the actual number being described.

"Subspecies," a compound built on "species," behaves identically as a zero-plural noun, following the exact same grammatical pattern as its root word regardless of how many taxonomic subdivisions are actually being described in a given sentence. Environmental policy documents often specify protections for "threatened and endangered species" as a fixed legal phrase, relying on the zero-plural form to cover both a single species and dozens listed together under the same regulation without any change in wording required. Field biologists sometimes debate whether a given population represents a distinct species or merely a regional variation within an existing one, a classification question that can shift the exact count of species recognized within a genus.

Common real mistakes

Writing "specie" as if it were the natural singular of "species" is a real and fairly common misconception — "specie" is actually an unrelated, older financial term for coined metal money, not a legitimate singular form of the biological noun, even though the resemblance misleads many writers into assuming otherwise. A further point worth noting: "speciation," the evolutionary process by which new species arise, is a fully regular abstract noun and shares no grammatical connection to the zero-plural behavior of "species" itself, despite obviously describing the process that creates the very thing the word names.

The wider pattern

"Species" belongs to the same small class of Latin -s nouns that never developed a distinct English plural, alongside "series" and, in certain specialized senses, "corps" — words where number is carried entirely by context rather than by any change in form.

Examples

• Scientists discovered a new species of frog deep in the rainforest.
• Several endangered species depend on this single wetland habitat.
• The species has adapted remarkably well to urban environments.
• Researchers catalogued dozens of species during the month-long expedition.
• This particular species is found only on one remote island.
• Climate change threatens species across every major ecosystem.
• The aquarium houses species from oceans around the world.
• A single invasive species can disrupt an entire local ecosystem.
• Conservationists are working to protect several critically endangered species.
• The field guide describes hundreds of native plant species.
• The reserve is home to several critically endangered species of primate.
• New species are still being discovered in remote, unexplored regions.
• The expedition confirmed the existence of a previously undocumented species.
• The botanical garden cultivates species collected from five continents.
• Invasive species can outcompete native plants within just a few seasons.
• The reef supports species found nowhere else on the planet.
• Habitat loss remains the leading threat facing most endangered species.