Species

classification · biology · life on Earth · taxonomy

Life's Basic Unit. A species is the smallest group we use to organize living things. Scientists think there are between 8 and 8.7 million species on Earth, but we've only found and named about 14% of them so far.

Making Babies Together. The main rule for a species is that any two members of the right sexes can make fertile babies together. A fertile baby is one that can also have its own babies someday.

Two-Part Names. Every species gets a special two-part name called a binomen. The first part is the genus (the bigger family group), and the second part is the specific name. For example, the boa constrictor snake's two-part name tells us it's a boa that constricts.

Different Ways to Identify. Scientists can identify a species by looking at DNA, body shape, behavior, or where it lives. For fossils, scientists use a special method called chronospecies because they can't test if ancient creatures could have babies together.