Echidna's 'digging walk' cultivates Australian soil
The cute Australian native can turn over 200 cubic metres of soil each year. Amy Middleton reports.
The short-beaked echidna enriches soil by way of its unique digging and tunnelling – and one animal can dig a whopping 200 cubic metres of soil a year, a new study in the Journal of Experimental Biology has revealed.
Digging, which makes up part of the echidna’s natural walk, is a form of bioturbation – a mixing process that increases nutrients and species diversity in soil. This is especially important because echidnas are the most widely-distributed terrestrial animals in Australia.
The short-beaked echidna (Tachyglossus aculeatus) is a monotreme, which means it’s a mammal that lays eggs. Echidnas and platypuses are the only living members of the monotreme family, which diverged from mammals around 166 million years ago. This makes them incredibly unique in their biology, and favourite species for researchers to study.
Christofer Clemente at the University of the Sunshine Coast in Queensland, Australia and colleagues focused the ways short-beaked echidna get around the terrain.
Their gait involves a neat combination of digging and striding which, according to the researchers, is a bizarre mix of mammalian and reptilian locomotion.
GPS and accelerometer data measured the locomotion of 11 short-beaked echidnas in Western Australia.
The team calculated that echidnas spend around 12% of their day digging.
On average, each echidna excavates 204 cubic metres of soil every 12 months, which means 12 echidnas could displace enough soil in a year to fill an Olympic swimming pool.
The researchers say their work “highlights the important contribution towards ecosystem health” made by short-beaked echidnas.
“The foraging pits produced by echidnas almost double the amount of water absorbed […] compared with undisturbed soil.”
Digging also helps to capture and retain leaf litter in soil, and traps organic matter below the surface, releasing nutrients into the soil which are then beneficial to resident species.
“Although most mammals associated with bioturbation in Australia have suffered considerable reductions in density and distribution post-European settlement, the short-beaked echidna is the Australian mammalian species least impacted,” the researchers write.
“Therefore, it may be one of Australia’s most important living bioturbators.”