The Koala (Phascolarctos cinereus) is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae.The Koala is found in coastal regions of eastern and southern Australia, from near Adelaide to the southern part of Cape York Peninsula. Populations also extend for considerable distances inland in regions with enough moisture to support suitable woodlands.
Females reach maturity at 2 to 3 years of age, males at 3 to 4 years. A healthy female Koala can produce one young each year for about 12 years. Gestation is 35 days. Twins are very rare. Mating normally occurs between December and March, the Southern Hemisphere's summer.
A baby Koala is referred to as a joey and is hairless, blind, and earless. At birth the joey, only a quarter of an inch long, crawls into the downward-facing pouch on the mother's belly and attaches itself to one of the two teats.Young remain hidden in the pouch for about six months, only feeding on milk. During this time they grow ears, eyes, and fur. The joey then begins to explore outside of the pouch.
Source: en.wikipedia.org/wiki/Koala - 09.04.2010
A Koala does not look thus alert all the time. The nocturnal animals are sleeping 18-20 hours the day.