Search

Echidnas are commonly known as 'spiny ant-eaters', but long-beaked echidnas (Zaglossus spp.) do not eat ants, whereas short-beaked echidnas (Tachyglossus aculeatus) eat other invertebrates as well as ants. The differences in skull morphology between short- and long-beaked echidnas are related to the differences in their diets, and I tested the hypothesis that there would be differences in beak length of short-beaked echidnas from populations with different diets. Published data on diet from echidnas from different parts of Australia show that echidnas from arid and semi-arid areas (subspecies acanthion) and Kangaroo Island (subspecies multiaculeatus) principally eat ants and termites, whereas the main dietary items of echidnas from south-eastern Australia (subspecies aculeatus) and Tasmania (subspecies setosus) are ants and scarab larvae. Using museum specimens and photographs I measured skull dimensions on echidnas from different parts of Australia: acanthion and multiaculeatus have narrower skulls and shorter beaks than aculeatus and setosus , with setosus being the only Australian subspecies where beak length exceeds cranium length. Australian short-beaked echidnas fall into two groups: aculeatus and setosus from the wetter east and south-east, which eat ant and scarab larvae, and the arid and semi-arid zone acanthion and multiaculeatus , with shorter, narrower skulls, and which eat ants and termites. Echidnas occur all over Australia, but echidnas from different regions vary greatly in the length of the spines and hair. This paper shows there are also big differences in beak length. Tasmanian echidnas have the longest beaks, whereas arid zone echidnas have very short beaks. Beak length is related to diet and feeding behaviour: longer beaks are better suited to probing for scarab larvae, while short beaks are better for ploughing through the soil for ants and termites. Diet, beak length and claw lengths divide Australian echidnas into two groups. [ABSTRACT FROM AUTHOR]