Short-beaked species of this mammal is a valuable ecosystem engineer
Courtesy of C. Clemente
With no nipples and reptilelike eggs, short-beaked echidnas look like a first draft of a mammal. Yet, as Australia’s other digging mammals decline from invasive predators, the well-defended echidna is getting new love as an ecosystem engineer.
The only mammals today that lay eggs are the four echidna species and the duck-billed platypus. Eggs are probably a holdover from the time before mammals split from reptiles. Each year or so, the short-beaked echidna (Tachyglossus aculeatus) lays one leathery egg “about the size of a grape,” says Christine Cooper of Curtin University in Perth. Instead of constructing a nest, mom deposits the egg in her version of a kangaroo pouch and waddles around with it.
When the egg hatches about 10 days later, two patches of pores in mom’s pouch ooze milk, and the baby laps it off her skin.