For most plants and animals, just listing the family, genus or species is enough to let biologists know what the other levels should be. The most common way to list the taxonomic name of an organism is to list the genus and species; this is known as binomial nomenclature, meaning a two-name system.
The grey jay is a relatively large songbird, though smaller than other jays. A typical adult grey jay is between 25 to 33 cm (9.8 to 13.0 in) long. Its wingspan is around 45 cm (18 in). It weighs about 65 to 70 g (2.3 to 2.5 oz). Adults have medium grey back feathers with a lighter grey underside.
The leopard seal is large and muscular, with a dark grey back and light grey on its stomach. Its throat is whitish with the black spots that give the seal its common name. Females are slightly larger than the males. The overall length of this seal is 2.4â3.5 m (7.9â11.5 ft) and weight is from 200 to 600 kilograms (440 to 1,320 lb).