An endling is the last known individual of a species or subspecies. Once the endling dies, the species becomes extinct. The word was coined in correspondence in the scientific journal Nature.
The last known thylacine (Tasmanian tiger), photographed at Hobart Zoo in 1933.
Martha, the last passenger pigeon, died in the Cincinnati Zoo on September 1, 1914.
A dusky seaside sparrow (Ammodramus maritimus nigrescens), officially declared extinct in 1990.
A quagga mare at the London Zoo in 1870. This is the only specimen photographed alive.
A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour, or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet. For example, Boa constrictor is one of the species of the genus Boa, with constrictor being the species' epithet.
All adult Eurasian blue tits share the same coloration, unmistakably identifying the morphospecies.
Ernst Mayr proposed the widely used Biological Species Concept of reproductive isolation in 1942.
Palaeontologists are limited to morphological evidence when deciding whether fossil life-forms like these Inoceramus bivalves formed a separate species.
Blackberries belong to any of hundreds of microspecies of the Rubus fruticosus species aggregate.