One animal can have many common names: cougar, mountain lion, puma, panther. Scientists everywhere use one name instead. The system comes from the ranks: each species gets a two-part name, its genus and then a specific name.
Key idea
A scientific name is genus + specific name, like Canis lupus for the gray wolf. The genus starts with a capital letter, the specific name is all lowercase, and the whole name is printed in italics (underlined when handwritten).
Why it works
Carl Linnaeus made this two-part system standard, for plants in 1753 and for animals in 1758. Because the first word is the genus, the name itself tells you something: animals that share a genus are close relatives. Canis lupus (gray wolf) and Canis latrans (coyote) are close kin; Vulpes vulpes (red fox) is in another genus.
Worked examples
Worked example: Write it right
How do you write the scientific name of the human?
- Genus: Homo, with a capital H.
- Specific name: sapiens, all lowercase.
- Print it in italics.
Answer: Homo sapiens
Worked example: Close relatives?
Which two are most closely related: Ursus americanus, Homarus americanus, Ursus arctos?
- Compare the first words: two are Ursus.
- The shared word "americanus" only means "from America".
Answer: Ursus americanus and Ursus arctos (two bears).
Common mistake
Capitalizing both words, or thinking two species with the same second word are relatives. Only the genus is capitalized, and only a shared genus shows close kinship. Check the first word, not the second.