Typically thought of the world’s oddest mammal, Australia’s beaver-like, duck-billed platypus reveals an array of weird traits: it lays eggs as a substitute of giving delivery to stay infants, sweats milk, has venomous spurs and is even outfitted with 10 intercourse chromosomes. Now, a global group of researchers led by College of Copenhagen has performed a singular mapping of the platypus genome and located solutions concerning the origins of some of its stranger options.

It lays eggs, however nurses, it’s toothless, has a venomous spur, has webbed ft, fur that glows and has 10 intercourse chromosomes. Ever since Europeans found the platypus in Australia in the course of the late 1700’s, the quirky, duck-billed, semiaquatic creature has baffled scientific researchers.

Modern-day researchers are nonetheless making an attempt to grasp how the platypus — usually thought of to be the world’s oddest mammal — received to be so distinctive. Their understandings have now superior, to an incredible diploma. For the primary time, a global group of researchers, led by College of Copenhagen biologists, has mapped a whole platypus genome. The research is revealed within the scientific journal, Nature.

“The whole genome has offered us with the solutions to how just a few of the platypus’ weird options emerged. On the identical time, decoding the genome for platypus is necessary for bettering our understanding of how different mammals developed — together with us people. It holds the important thing as to why we and different eutheria mammals developed to grow to be animals that give delivery to stay younger as a substitute of egg-laying animals,” explains Professor Guojie Zhang of the Division of Biology.

The platypus belongs to an historic group of mammals — monotremes — which existed thousands and thousands of years previous to the emergence of any modern-day mammal.

“Certainly, the platypus belongs to the Mammalia class. However genetically, it’s a combination of mammals, birds and reptiles. It has preserved a lot of its ancestors’ authentic options — which in all probability contribute to its success in adapting to the surroundings they stay in,” says Professor Zhang.

Lays eggs, sweats milk and has no tooth

One of many platypus’ most uncommon traits is that, whereas it lays eggs, it additionally has mammary glands used to feed its infants, not by nipples, however by milk — which is sweat from its physique.

Throughout our personal evolution, we people misplaced all three so-called vitellogenin genes, every of which is necessary for the manufacturing of egg yolks. Chickens then again, proceed to have all three. The research demonstrates that platypuses nonetheless carry one among these three vitellogenin genes, regardless of having misplaced the opposite two roughly 130 million years in the past. The platypus continues to put eggs by advantage of this one remaining gene. That is in all probability as a result of it’s not as depending on creating yolk proteins as birds and reptiles are, as platypuses produce milk for his or her younger.

In all different mammals, vitellogenin genes have been changed with casein genes, that are answerable for our skill to provide casein protein, a serious element in mammalian milk. The brand new analysis demonstrates that the platypus carries casein genes as effectively, and that the composition of their milk is thereby fairly just like that of cows, people and different mammals.

“It informs us that milk manufacturing in all extant mammal species has been developed by the identical set of genes derived from a typical ancestor which lived greater than 170 million years in the past — alongside the early dinosaurs within the Jurassic interval,” says Guojie Zhang.

One other trait that makes the platypus so distinctive is that, in contrast to the overwhelming majority of mammals, it’s toothless. Though this monotremes’ nearest ancestors had been toothed, the fashionable platypus is provided with two horn plates which might be used to mash meals. The research reveals that the platypus misplaced its tooth roughly 120 million years in the past, when 4 of the eight genes answerable for tooth growth disappeared.

Solely animal with 10 intercourse chromosomes

One more platypus oddity investigated by the researchers was how their intercourse is decided. Each people and each different mammal on Earth have two intercourse chromosomes that decide intercourse – the X and Y chromosome system wherein XX is feminine and XY is male. The monotremes, nevertheless, together with our duck-billed associates from Down Beneath, have 10 intercourse chromosomes, with 5 Y and 5 X chromosomes.

Because of the near-complete chromosomal degree genomes, researchers can now recommend that these 10 intercourse chromosomes within the ancestors of the monotremes had been organized in a hoop kind which was later damaged away into many small items of X and Y chromosomes. On the identical time, the genome mapping reveals that almost all of monotreme intercourse chromosomes have extra in frequent with chickens than with people. However what it exhibits, is an evolutionary hyperlink between mammals and birds.


  • The platypus is endemic to japanese Australia and Tasmania. It’s a protected species and labeled by the IUCN as near-threatened.
  • Among the many the reason why platypuses are thought of mammals: they’ve mammary glands, develop hair and have three bones of their center ears. Every trait helps to outline a mammal.
  • The platypus belongs to the mammalian order monotreme, so named as a result of monotremes use a singular opening for urination, defecation and sexual copy.
  • The animal is a superb swimmer and spends a lot of its time attempting to find bugs and shellfish in rivers.
  • Its distinctive beak is crammed with electrical sensors that are used to find prey in muddy river beds.
  • The male platypus has a venomous spur behind every of its hind legs. The venom is toxic sufficient to kill a canine and is deployed when males combat for territory.
  • One other 2020 research demonstrated that platypus fur is fluorescent. The animal’s brown fur displays a blue-green shade when positioned beneath UV mild. (supply: https://doi.org/10.1515/mammalia-2020-0027)


  • Superior gene sequencing know-how that mixes quite a few cutting-edge strategies has allowed the analysis group to map a near-complete genome on the chromosomal degree from each the platypus and its cousin, the echidna– the one two presently dwelling sorts of monotreme animals. The gene information fills in 90 % of the gaps in earlier genetic mappings. Over 96% of the genome sequences are positioned within the chromosomes now.
  • The researchers have in contrast the monotreme genes and genomes from chickens, people, rats, Tasmanian devils and lizards.
  • Along with Yang Zhou (lead writer) and Guojie Zhang of the College of Copenhagen, the analysis was carried out by, amongst others: Linda Shearwin-Whyatt of The College of Adelaide (Australia) and Jing Li of Zhejiang College (China). A whole listing of the authors will be discovered within the analysis article.
  • The research has simply been revealed within the prestigious scientific journal, Nature.


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