Let’s talk about egg laying mammals- sounds crazy but it’s true! There is a very small group of mammals that actually do lay eggs. They are called Monotremes which include the duckbilled platypus and the echidna.
Duck-billed platypus-
The breeding season lasts from June through October. Male platypuses are polygmous, meaning they mate with more than one female during the breeding season. The females have two ovaries but strangely only the left one is functional. A typical platypus burrow entrance is 30 cm about water level but after mating the female digs a deeper and more elaborate burrow about 20 m deep. These elaborate burrows have several chambers and are blocked at intervals with plugs. This may act as a safeguard against rising water, predators, or for regulating humidity and temperature. Leaves on the bottom of the burrow act as bedding and retaining moisture.
Once the platypuses have mated, the eggs develop in utero for 28 days and then require 10 days of external incubation before hatching. She lays 3 thick leathery eggs, about 11 millimeters each, in one of her burrow chambers and curls around them. Incubation happens in 3 phases. 1st phase- the embryo has no functional organs and relies on the yolk sac for nourishment. 2nd phase- the embryo develops digits. 3rd phase- the egg tooth develops.
Once hatched the baby platypuses are blind, hairless, and vulnerable. They drink their mother’s milk for 3-4 months before emerging, once thye’re ready to swim. Interestingly, the female does have mammory glands but lacks teats. The milk is secreted through pores in the skin and runs down small groves where it pools on her abdomen. Here the young lap up the milk.
www.duckbilledplatypus.info
baby platypuses
Echidna-
The breeding season lasts from the end of June through September. The males form “trains” where 2 to 10 males form a line and follow one another searching for females. Males may join several trains during the breeding season. The females have two ovaries and both are functional.
Two weeks after mating the female lays 1 egg, it’s soft and leathery and no bigger than a grape. She rolls this egg into a pouch on her abdomen. After 10 days in the pouch a baby echinda or puggle hatches.
- No, not this kind of Puggle
The puggle is no bigger than a jellybean at this point. The baby uses it’s tiny strong claws to grip onto special hairs in the pouch. Much like the platypus, the echinda also lacks teats. The puggle laps up it’s mother’s milk from special glands. 6-8 weeks after hatching the puggle’s spines begin to hardern and cover it’s entire body. At this point it leaves it’s mother pouch and stays in a burrow. The mother leaves but returns every 5-10 days to feed it’s young. At about 7 months old the young echidna is big enough to go out into the world.
environment.nsw.au/resourses/nature/Factsheet3Echidnas.pdf
Echidna Puggle
Happy 1.5 year anniversary to Kimberly being a keeper at the Museum! For regular blog readers, you’ve already got to know Kimberly quite well by reading her posts. She’s passionate about lemurs, animal training, and the natural world. She has a lot of 
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