Many of us love seeing an echidna. Their shuffling stroll, inquisitive gaze and protecting spines are unmistakable, coupled with the coarse hair and stubby beak.
They appear like a unusual mix of hedgehog and anteater. But they’re not associated to those creatures in any respect. They’re much more mysterious and uncommon than generally assumed.
Australia has only one species, the short-beaked echidna (Tachyglossus aculeatus), which roams nearly the whole continent. But it has 5 subspecies, which are sometimes markedly totally different. Tasmanian echidnas are a lot hairier and Kangaroo Island echidnas be a part of lengthy mating trains.
Here are 4 issues that make echidnas exceptional.
1: They’re historic egg-laying mammals
Short-beaked echidnas are one in all simply 5 species of monotreme surviving on the 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 via 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 consider echidnas started as platypuses who left the water and developed spines. That’s as a result of platypus fossils return about 60 million years and echidnas solely 1 / 4 of that.
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Remarkably, the echidna nonetheless has rudimentary electroreception. It is sensible the platypus depends on its skill to sense electric fields when it’s looking on the backside of darkish rivers, given electric fields unfold extra simply via water. But on land? It’s probably echidnas use this skill to sense ants and termites shifting via moist soil.
It most likely obtained 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, akin 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 can discover 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 can be accustomed to is Tachyglossus aculeatus aculeatus, widespread throughout Queensland, New South Wales, South Australia and Victoria. You can consider this as “echidna classic”.
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.
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You may suppose subspecies wouldn’t be too totally different – in any other case they’d be totally different species, proper? In reality, subspecies might be markedly totally 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 effectively tailored to the chilly, boasting a lushness of additional hair. Sometimes you may’t even see their spines amidst their hair.
2: From deserts to snow, echidnas are remarkably adaptable
Remarkably, the subspecies have very totally different approaches to mating. You might need seen movies of Kangaroo Island mating trains, a spectacle the place as much as 11 males fervently pursue a single feminine through the breeding season. Other subspecies do that, nevertheless it’s commonest on Kangaroo Island. Scientists consider this is because of inhabitants density.
Pregnancy normally lasts about three weeks after mating for Kangaroo Island echidnas, adopted by an extended lactation interval of 30 weeks for the newborn puggle.
But Tasmanian echidnas behave very in a different way. During 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. They even have a shorter lactation interval, of solely 21 weeks.
What in regards to the echidna subspecies we’re most accustomed to? T. aculeatus aculeatus has a equally quick 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 frequent?
Marsupials bear dwell younger after they’re very small and allow them to full their improvement in a pouch. Despite this key distinction with monotremes, there’s a captivating 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. Both are within the somite stage, the place paired blocks of tissue type alongside the notochord, the momentary precursor to the spinal twine, 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.
Yet regardless of hundreds of thousands of years of evolutionary strain and change, these very totally 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 subsequent time you notice the standard echidna, take a second to understand what a exceptional creature it’s.
