Platypus

Platypuses construct two kinds of burrows in the banks of rivers and streams. A very simple burrow provides shelter for both males and females outside the breeding season, and is retained by males during the breeding season. At this time, the female constructs a deeper, more elaborate nesting burrow. Commonly, this burrow opens about 1 ft (0.3 m) above the water level and goes back into the bank as far as 59 ft (18 m). The female usually softens a portion of the nest with folded wet leaves. Whenever the female leaves young in her nesting burrow, she plugs the exit with soil.

The female usually lays two eggs, although sometimes she lays one or three. Typically, the eggs are about 0.7 in (1.7 cm) in diameter, are a bit rounder than most bird eggs, and are soft and compressible with a pliant shell. After she lays her eggs, the female curls around them, incubating them for seven to 10 days. During this time, she only leaves her nest to wet her fur and to defecate. Measuring about 1 in (2.5 cm) long, a newly hatched platypus is blind and nude. The female platypus has no teats, therefore, she feeds her young on milk secreted through skin pores on her abdomen. The milk flows into two milk grooves on the abdomen and the young lap up the pools of milk. When the young platypus is about four months old, it leaves the burrow.

When the first platypus was sent to England, scientists thought it was a fake. Years passed before the existence of the animal was proven. Although platypus populations were formerly reduced by hunting for the fur trade, effective government conservation efforts have resulted in a successful comeback. Under the Australian Endangered Species Act of 1992 guidelines, today the platypus is neither on the endangered list nor officially on the list of vulnerable species. However, serious concern is raised because the platypus range closely follows densely populated regions of Australia where human activity greatly affects waterways. The species habitat may be disrupted by dams, irrigation projects, or pollution.