They sense electric fields, tolerate snow and have ‘mating trains’: 4 reasons echidnas really are remarkable

Subject :Environment

Section: Species in news

Echidnas:

They look like a quirky blend of hedgehog and anteater. But they’re not related to these creatures at all.
Australia has just one species, the short-beaked echidna (Tachyglossus aculeatus), which roams virtually the entire continent.
It has five subspecies.
Tasmanian echidnas are much hairier and Kangaroo Island echidnas join long mating trains.

Four things that make echidnas remarkable:

They’re ancient egg-laying mammals
- First Nations groups knew the echidna by many other names, such as bigibila (Gamilaraay) and yinarlingi (Warlpiri).
- Short-beaked echidnas are one of just five species of monotreme surviving in the world, alongside the platypus.
- Three worm-eating long-beaked echidna species found on the island of New Guinea.
- These ancient mammals lay eggs through their cloacas(monotreme means one opening) and incubate them in a pouch-like skin fold, nurturing their tiny, jellybean-sized young after hatching.
- Scientists believe echidnas began as platypuses who left the water and evolved spines. That’s because platypus fossils go back about 60 million years and echidnas only a quarter of that.
- The echidna still has rudimentary electroreception. While platypus relies on its ability to sense electric fields when it’s hunting at the bottom of dark rivers, given electric fields spread more easily through water. Echidnas use this ability to sense ants and termites moving through moist soil.

From deserts to snow, echidnas are remarkably adaptable
- They can tolerate a broad climate ranges.
- They are being found on northern tropical savannah amid intense humidity, on coastal heaths and forests, in arid deserts and even on snowy mountains.
- The five subspecies of short-beaked echidna have distinct geographic regions.
  - Tachyglossus aculeatus aculeatus, widespread across Queensland, New South Wales, South Australia and Victoria.
  - Kangaroo Island’s T aculeatus multiaculeatus
  - Tasmania’s T aculeatus setosus,
  - The Northern Territory and Western Australia’s T aculeatus acanthion and
  - The tropical subspecies T aculeatus lawesii found in Northern Queensland and Papua New Guinea.
- Kangaroo Island echidnas have longer, thinner and paler spines — and more of them, compared to the mainland species.
- Tasmanian echidnas are well adapted to the cold, boasting a lushness of extra hair.

Mating trains and hibernation games
- Pregnancy usually lasts about three weeks after mating for Kangaroo Island echidnas, followed by a long lactation period of 30 weeks for the baby puggle.
- Tasmanian echidnas have a shorter lactation period, of only 21 weeks.

What do marsupials and monotremes have in common?
- Monotremes branched off from other mammals early on, between 160 and 217 million years ago. Marsupials branched off later, at around 143–178 million years ago.
- Yet despite millions of years of evolutionary pressure and change, these very different animals still hit a key embryo milestone at the same time. This striking parallel suggests the intricate process has been conserved for over 184 million years.