Koala Temporal range: 0.7–0 Ma PreꞒꞒOSDCPTJKPgN ↓ Middle Pleistocene – Recent Koala climbing tree.jpg Conservation status
Vulnerable (IUCN 3.1)[1] Scientific classification edit Kingdom: Animalia Phylum: Chordata Class: Mammalia Infraclass: Marsupialia Order: Diprotodontia Family: Phascolarctidae Genus: Phascolarctos Species: P. cinereus Binomial name Phascolarctos cinereus (Goldfuss, 1817) Koala Range.jpg Koala range Native Introduced Synonyms[2]: 45 [3] Lipurus cinereus Goldfuss, 1817 Marodactylus cinereus Goldfuss, 1820 Phascolarctos fuscus Desmarest, 1820 Phascolarctos flindersii Lesson, 1827 Phascolarctos koala J.E. Gray, 1827 Koala subiens Burnett, 1830 The koala or, inaccurately, koala bear (Phascolarctos cinereus), is an arboreal herbivorous marsupial native to Australia. It is the only extant representative of the family Phascolarctidae and its closest living relatives are the wombats. The koala is found in coastal areas of the mainland’s eastern and southern regions, inhabiting Queensland, New South Wales, Victoria, and South Australia. It is easily recognisable by its stout, tailless body and large head with round, fluffy ears and large, spoon-shaped nose. The koala has a body length of 60–85 cm (24–33 in) and weighs 4–15 kg (9–33 lb). Fur colour ranges from silver grey to chocolate brown. Koalas from the northern populations are typically smaller and lighter in colour than their counterparts further south. These populations possibly are separate subspecies, but this is disputed.
Koalas typically inhabit open Eucalyptus woodland, as the leaves of these trees make up most of their diet. This eucalypt diet has low nutritional and caloric content and contains toxins that deter most other mammals from feeding on it. Koalas are largely sedentary and sleep up to twenty hours a day. They are asocial animals, and bonding exists only between mothers and dependent offspring. Adult males communicate with loud bellows that intimidate rivals and attract mates. Males mark their presence with secretions from scent glands located on their chests. Being marsupials, koalas give birth to underdeveloped young that crawl into their mothers’ pouches, where they stay for the first six to seven months of their lives. These young koalas, known as joeys, are fully weaned around a year old. Koalas have few natural predators and parasites, but are threatened by various pathogens, such as Chlamydiaceae bacteria and koala retrovirus.
Because of its distinctive appearance, the koala along with the kangaroos are recognised worldwide as symbols of Australia. They were hunted by Indigenous Australians and depicted in myths and cave art for millennia. The first recorded encounter between a European and a koala was in 1798, and an image of the animal was published in 1810 by naturalist George Perry. Botanist Robert Brown wrote the first detailed scientific description of the koala in 1814, although his work remained unpublished for 180 years. Popular artist John Gould illustrated and described the koala, introducing the species to the general British public. Further details about the animal’s biology were revealed in the 19th century by several English scientists. Koalas are listed as a vulnerable species by the International Union for Conservation of Nature. Among the many threats to their existence are habitat destruction caused by agriculture, urbanisation, droughts, and associated bushfires, some related to climate change. In February of 2022, the koala was officially listed as endangered in the Australian Capital Territory, New South Wales, and Queensland.
Etymology The word koala comes from the Dharug gula, meaning no water. Although the vowel ‘u’ was originally written in the English orthography as “oo” (in spellings such as coola or koolah — two syllables), the spelling later became “oa” and the word is now pronounced in three syllables, possibly in error.[4]
Adopted by white settlers, “koala” became one of several hundred Aboriginal loan words in Australian English, where it was also commonly referred to as “native bear”,[5] later “koala bear”, for its supposed resemblance to a bear.[6] It is also one of several Aboriginal words that made it into International English, alongside e.g. “didgeridoo” and “kangaroo."[6] The generic name, Phascolarctos, is derived from the Greek words phaskolos “pouch” and arktos “bear”. The specific name, cinereus, is Latin for “ash coloured”.[7]
Taxonomy and evolution The koala was given its generic name Phascolarctos in 1816 by French zoologist Henri Marie Ducrotay de Blainville,[8] who would not give it a specific name until further review. In 1819, German zoologist Georg August Goldfuss gave it the binomial Lipurus cinereus. Because Phascolarctos was published first, according to the International Code of Zoological Nomenclature, it has priority as the official name of the genus.[9]: 58–59 French naturalist Anselme Gaëtan Desmarest proposed the name Phascolarctos fuscus in 1820, suggesting that the brown-coloured versions were a different species than the grey ones. Other names suggested by European authors included Marodactylus cinereus by Goldfuss in 1820, P. flindersii by René Primevère Lesson in 1827, and P. koala by John Edward Gray in 1827.[2]: 45
The koala is classified with wombats (family Vombatidae) and several extinct families (including marsupial tapirs, marsupial lions and giant wombats) in the suborder Vombatiformes within the order Diprotodontia.[10] The Vombatiformes are a sister group to a clade that includes macropods (kangaroos and wallabies) and possums.[11] The koala’s lineage possibly branched off around 40 million years ago during the Eocene.[12]
Reconstructions of the ancient koalas Nimiokoala (larger), and Litokoala (smaller), from the Miocene Riversleigh Fauna The modern koala is the only extant member of Phascolarctidae, a family that once included several genera and species. During the Oligocene and Miocene, koalas lived in rainforests and had less specialised diets.[13] Some species, such as the Riversleigh rainforest koala (Nimiokoala greystanesi) and some species of Perikoala, were around the same size as the modern koala, while others, such as species of Litokoala, were one-half to two-thirds its size.[14] Like the modern species, prehistoric koalas had well developed ear structures which suggests that long-distance vocalising and sedentism developed early.[13] During the Miocene, the Australian continent began drying out, leading to the decline of rainforests and the spread of open Eucalyptus woodlands. The genus Phascolarctos split from Litokoala in the late Miocene[13][15] and had several adaptations that allowed it to live on a specialised eucalyptus diet: a shifting of the palate towards the front of the skull; larger molars and premolars; smaller pterygoid fossa;[13] and a larger gap between the molar and the incisor teeth.[16]: 226
P. cinereus may have emerged as a dwarf form of the giant koala (P. stirtoni). The reduction in the size of large mammals has been seen as a common phenomenon worldwide during the late Pleistocene, and several Australian mammals, such as the agile wallaby, are traditionally believed to have resulted from this dwarfing. A 2008 study questions this hypothesis, noting that P. cinereus and P. stirtoni were sympatric during the middle to late Pleistocene, and possibly as early as the Pliocene.[17] The fossil record of the modern koala extends back at least to the middle Pleistocene.[18]