Short-beaked echidna (Tachyglossus aculeatus)

Family Tachyglossidae

The short-beaked echidna is a monotreme (egg-laying mammal) found throughout mainland Australia as well as Tasmania, lowland New Guinea and Kangaroo island.  By distribution alone it can be considered the most successful Australian native mammal.  The species Tachyglossus aculeatus is divided into five subspecies based on geographic distribution, the relative amounts of spines and hair, and the claws on the hind feet.  The keratinous spines are modified from hairs, and in all subspecies some amount of hair is present between the spines, with a higher proportion of hair in cool climate subspecies.  The diet of echidnas mostly consists of ants and termites, but the larvae of cockchafer beetles and pasture grubs make up a significant proportion of the diet in many regions.

The beak (actually an extended nose) of the echidna is equipped with mechano- and electroreceptors, but there is uncertainty as to how effective the electroreceptors are in the wild. Short-beaked echidnas can detect electrical fields down to 1.8 mV/cm (similar to the threshold for individual infraorbital fibres), but that is for a field applied to water in a trough (Gregory et al., 1989), rather than the open air. In the natural setting, the snout tip is essentially functioning as a thrust probe sensor, detecting weak electrical signals from prey embedded in moist soil, with no amplification or directional capability.

Gregory JE, Iggo A, McIntyre AK and Proske U (1989) Responses of electroreceptors in the snout of the echidna. Journal of Physiology London 414, 521–538.