species: Quick Facts

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A nautilus mollusk with a spiral, brown-and-white striped shell and numerous white tentacles extending from its soft body, set against a dark background.

A diagram showing the hierarchy of animal classification in taxonomy, with colored boxes arranged from broadest to most specific: domain, kingdom, phylum, class, order, family, genus, and species.

Adaptive radiation in Galapagos finches

A diagram illustrating speciation, showing how a parent species splits into isolated populations due to physical or climatic barriers, eventually evolving into two distinct new species labeled A and B. Text explains each stage of population separation and genetic divergence.

A branching phylogenetic tree diagram shows evolutionary relationships among various organisms, from Neurospora mold to humans, based on differences in cytochrome c gene sequences. Each branch is labeled with nucleotide substitution values and illustrated with animal or organism icons along the tree.

A circular chart illustrates the estimated number of known living species, divided into segments for plants, monerans, protists, fungi, animals excluding insects, and animals that are insects only, with insects occupying the largest portion.

Close-up of a king cobra overlaid with question marks, a drawn crown, and an arrow pointing to the snake

Why are rainforests so important?

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Topics

polytypic species What are the shortest and longest binomial names?Why Do Scientific Names Have Two Parts?Gorilla gorilla, Sula sula, and Other Animals Whose Names Are Tautonyms—the Same for Genus and Species pioneer species endemic species r-selected species Eusocial species K-selected species relict species genus cultivar

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Key People

John Ray, detail of an oil painting; in the National Portrait Gallery, London

John Ray

English naturalist

greylag. Flock of Greylag geese during their winter migration at Bosque del Apache National Refugee, New Mexico. greylag goose (Anser anser)

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