Platypus feed primarily on aquatic invertebrates such as insect larvae, shrimps, swimming beetles, water bugs, tadpoles, worms, freshwater pea mussels and snails. They forage most of their food from the bottom of the river however they occasionally catch cicadas and moths from the water surface. They store their food in their cheek-pouches then chew the food using horny, grinding plates, while they float to rest on the water surface.
When foraging underwater they close their eyes, ears and nostrils and use their bill as the primary sense organ. Their bill is actually a sixth sense as it contains thousands of electro-receptor cells that allow them to detect electrical impulses in the water that are given off by the muscle movement of their prey. Platypus need to eat around 30% of their own body weight daily to survive. In tough times they can live off a reserve of fat stored in their tails.
Platypuses are semi-aquatic living in rivers, streams and lakes across their range. They favour waterways without a strong current and that are less than 5m deep as they cannot dive deeper. They like well vegetated banks, which allow for secure burrows to be built amongst the root systems of the plants. Its burrow is distinguished by oval sections and can be up to 30 metres long. The trees also shade the water and leaves falling into the water and decaying helps to support the insects that the Platypus likes to eat. This vegetation is so important to the Platypus that there is a direct correlation between the amount of vegetation on the bank and the numbers of platypus in the area.
Platypuses are grouped in a separate order of mammals known as monotremes, which are egg laying mammals. They reach sexual maturity at 2 years of age and generally mate between August and November. Courtship includes aquatic activities such as rolling sideways together, diving, touching and passing. The males have also been observed grasping a female’s tail with its bill. Mating occurs in the water.
After mating, a pregnant female builds a nest in a long complex burrow in less than a week. She spends a further 4-5 days collecting wet nesting material to prevent her eggs and hatchlings from drying out. Gestation lasts 21 days and during this egg incubation period, a female holds 1-3 eggs pressed by her tail to her belly, while curled up.
When the young hatch, the female starts secreting milk and the young Platypus suckle from the two milk patches covered by fur on the female’s abdomen. The female spends most of this time with her young in the burrow, and as the young grow she increasingly leaves them to forage. After 3-4 months, towards the end of the summer, the young emerge from the burrow as young independent animals.