Many people love seeing an echidna.
Their shuffling stroll, inquisitive gaze and protecting spines are unmistakable, coupled with the coarse hair and stubby beak.
They seem like a unusual mix of hedgehog and anteater.
However they’re not associated to those creatures in any respect.
They’re much more mysterious and strange than generally assumed.
Australia has only one species, the short-beaked echidna (Tachyglossus aculeatus), which roams nearly all the continent.
Nevertheless it has 5 subspecies, which are sometimes markedly completely different.
Tasmanian echidnas are a lot hairier and Kangaroo Island echidnas be a part of lengthy mating trains.
Listed below are 4 issues that make echidnas exceptional.
1: They’re historic egg-laying mammals
Brief-beaked echidnas are considered one of simply 5 species of monotreme surviving on this planet, alongside the platypus and three worm-eating long-beaked echidna species discovered on the island of New Guinea.
Our acquainted short-beaked echidnas can weigh as much as six kilograms—however the Western long-beaked echidna can get a lot bigger at as much as 16kg.
These historic mammals lay eggs by their cloacas (monotreme means one opening) and incubate them in a pouch-like pores and skin fold, nurturing their tiny, jellybean-sized younger after hatching.
Scientists imagine echidnas started as platypuses who left the water and advanced spines. That’s as a result of platypus fossils return about 60 million years and echidnas solely 1 / 4 of that.
Remarkably, the echidna nonetheless has rudimentary electroreception. It is smart the platypus depends on its capability to sense electrical fields when it’s searching on the backside of darkish rivers, given electrical fields unfold extra simply by water. However on land? It’s seemingly echidnas use this capability to sense ants and termites shifting by moist soil.
It most likely bought its English identify in homage to the Greek mythological determine Echidna, who was half-woman, half-snake, and the mom of Cerberus and Sphinx. This was to indicate the animal’s mixture of half-reptilian, half-mammal traits. First Nations teams knew the echidna by many different names, corresponding to bigibila (Gamilaraay) and yinarlingi (Warlpiri).
2: From deserts to snow, echidnas are remarkably adaptable
There are few different creatures capable of tolerate local weather ranges as broad. You’ll find echidnas on northern tropical savannah amid intense humidity, on coastal heaths and forests, in arid deserts and even on snowy mountains.
The 5 subspecies of short-beaked echidna have distinct geographic areas. The one most of us will probably be acquainted with is Tachyglossus aculeatus aculeatus, widespread throughout Queensland, New South Wales, South Australia and Victoria. You possibly can consider this as “echidna basic”.
Then there’s 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 present in Northern Queensland and Papua New Guinea.
You may suppose subspecies wouldn’t be too completely different—in any other case they’d be completely different species, proper? In reality, subspecies could be markedly completely different, with variations to hairiness and the size and width of spines.
Kangaroo Island echidnas have longer, thinner, and paler spines—and extra of them, in comparison with the mainland species. Tasmanian echidnas are nicely tailored to the chilly, boasting a lushness of additional hair. Generally you’ll be able to’t even see their spines amidst their hair.
3: Mating trains and hibernation video games
Remarkably, the subspecies have very completely different approaches to mating. You may need seen movies of Kangaroo Island mating trains, a spectacle the place as much as 11 males fervently pursue a single feminine in the course of the breeding season. Different subspecies do that, nevertheless it’s most typical on Kangaroo Island. Scientists imagine this is because of inhabitants density.
Being pregnant often lasts about three weeks after mating for Kangaroo Island echidnas, adopted by a protracted lactation interval of 30 weeks for the child puggle.
However Tasmanian echidnas behave very otherwise. Through the winter mating season, males hunt down hibernating females and wake them as much as mate. Intriguingly, females can put their being pregnant on maintain and return into hibernation. Additionally they have a shorter lactation interval, of solely 21 weeks.
What concerning the echidna subspecies we’re most acquainted with? T. aculeatus aculeatus has a equally brief lactation interval (23 weeks), however hardly ever engages in mating prepare conditions. After watching the pregnancies of 20 of those echidnas, my colleagues and I found this subspecies takes simply 16–17 days to go from mating to egg laying.
4: What do marsupials and monotremes have in widespread?
Marsupials bear dwell younger after they’re very small and allow them to full their improvement in a pouch. Regardless of this key distinction with monotremes, there’s an interesting similarity between Australia’s two most well-known mammal households.
At 17 days after conception, the embryo of the tammar wallaby (Macropus eugenii) hits nearly precisely the identical developmental milestone as echidna embryos. Each are within the somite stage, the place paired blocks of tissue kind alongside the notochord, the short-term precursor to the spinal wire, and every have round 20 somites.
What’s exceptional about this? Monotremes branched off from different mammals early on, between 160 and 217 million years in the past. Marsupials branched off later, at round 143–178 million years in the past.
But regardless of thousands and thousands of years of evolutionary stress and alter, these very completely different animals nonetheless hit a key embryo milestone on the identical time. This putting parallel suggests the intricate course of has been conserved for over 184 million years.
In echidnas, this milestone is tied to egg-laying—the embryo is packaged up in a leathery egg the scale of a grape and laid into the mom’s pouch. The child puggle hatches 10–11 days later. In tammar wallabies, the embryo continues to develop in-utero for an additional 9–10 days earlier than being born.
So the following time you see the common-or-garden echidna, take a second to understand what a exceptional creature it’s.
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This article by Kate Dutton-Regester, The Dialog was first publishd by Phys.org on 28 August 2023. Lead Picture: Shutterstock.