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No. 74: Mar-Apr 1991

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Echidna Eccentricities

Monotremes: platypus and one of two species of echidnas
Monotremes: platypus (below); one of two species of echidnas (above)
The echidna is one of the monotremes-- an egg-laying mammal. Like its relative, the platypus, it is a strange mixture of mammalian, marsupial, and reptilian characteristics. For example, echidna eggs are soft and leathery, like those of reptiles, but they are brooded in a marsupial-like pouch. The emerging baby echidna has an egg tooth like the birds and reptiles, while the adult has no teeth at all. Rather, it has a narrow snout through which it ingests ants and termites caught on its sticky tongue. In this it resembles the mammalian ant-eaters, which are also toothless but an ocean away from Australia. In fact, the echidna is often called a "spiny anteater" for it has the sharp spines of a hedgehog or porcupine.

There are more anatomical peculiarities, but let us focus on the echidna's strange behavior during the mating season. At this time, 2 to 8 echidnas can be seen roaming the Australian bush in "trains" headed by a female with the smallest male acting as a caboose. When mating time arrives, the female anchors herself to a tree with her forelegs. To-gether the males dig a circular "mating rut" up to 10 inches deep around the tree. (Australians have puzzled over these circular trenches for years.) Eventually the strongest male evicts the other males from the trench, the purpose of which now becomes apparent. As the old saying goes, porcupines make love very. Well, the echidna has an interesting technique; he simple lays on his side in the trench under the female! (Rismiller, Peggy D., and Seymour, Roger S.; "The Echidna," Scientific American, 264:96, February 1991.)

Reference. Many additional echidna "eccentricities" can be found in our catalog Biological Anomalies: Mammals I and II. For more information on these books, visit: here.

From Science Frontiers #74, MAR-APR 1991. � 1991-2000 William R. Corliss