About 8.7 million plants, animals, fungi and single-celled organisms are thought to exist on Earth, although estimates for this figure range from 3 million to 100 million (1). Around 1.7 million species have already been classified, but this leaves the vast majority of life on Earth undescribed or undiscovered (2). Most of those species yet to be discovered are likely to be tiny, such as bacteria and insects, and inhabit poorly explored areas such as the deep ocean and soil (1) (2). However, larger animals, such as rodents, snakes, salamanders, and even primates, are still being found (2) (3). Between 1999 and 2010, a staggering 615 new species were discovered on the island of Madagascar alone, including 69 amphibians, 61 reptiles and 41 mammals (4).
A newly discovered species may be a species that is completely new to science, or one which has previously been described but is subsequently found to be made up of two or more separate species (5). To be certain that a discovery is an entirely new species, scientists collect a specimen and compare its characteristics to those of existing species to determine whether or not the specimen is sufficiently different from any other species already described. Extensive review and analysis through checking scientific literature and consulting other experts is also needed before a species can confidently be assigned a scientific name (2).
Morphological, behavioural and genetic characteristics are used to identify a species. Scientists analyse key morphological features, for example the shape of the bones or the reproductive organs. Sound or video recordings of a species in the wild may also be used to document behavioural traits, for example specific vocalisations or courtship displays (2).
The analysis of molecular and genetic characteristics, such as chromosome shape or the sequence of a particular segment of DNA, is also an important tool in discovering new species. Genetic barcoding is a process whereby scientists compare a key fragment of DNA from a specimen against the DNA of thousands of other species, and this technique is becoming a vital tool in identifying both new and existing species (2).
Once an organism is confirmed as a new and unique species, it has to be formally described in a recognised scientific publication and assigned a scientific name (2).