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.