The Curious Case of the Platypus

The platypus is native to Australia. (Photo Credit: Peter Scoones/Photo Researchers, Inc.)

The platypus is a curious animal. It has a bill like a duck, it produces milk and has fur like a mammal, and it lays eggs like a reptile. Scientists recently sequenced the entire genome of a platypus and discovered that its odd appearance is in fact a testament to its bird, reptile, and mammal ancestors.

Natural History

A platypus (scientific name Ornithorhynchus anatinus) is an animal like no other. It is classified as a monotreme. Animals that are classified as monotremes are mammals that lay eggs. In addition to the platypus, there are two kinds of echidna that are also classified as monotremes. Platypuses and echidnas are endemic to the South Pacific and are only found in Australia, Tasmania, and New Guinea.

Platypuses live in lakes, rivers, and streams in eastern Australia. Characteristics of a platypus body include waterproof fur, webbed feet, and a horizontally-flattened tail to aid in movement underwater. The platypus has extremely sensitive senses of sight, smell, and hearing. When underwater, the platypus closes its eyes and ears.

Unusual Characteristics

Both male and female platypuses are born with a spur on each hind leg. While females lose their spur within the first year of their life, males retain their leg spurs over their entire lifetime. The spur is a claw-shaped growth that is connected to a venom gland. Males use the spurs to defend themselves against predators and competing male platypuses during mating season. The spur is very sharp and can inflict a very serious wound. While strong enough to kill a large dog, the venom does not appear to cause life-threatening injuries to humans.

A male platypus has a sharp spur on its hind foot that packs a venomous punch. (Photo Credit: ANT Photo Library/Photo Researchers, Inc.)

When underwater, the platypus uses its super-sensitive bill to detect prey. Unlike a duck’s hard bill, a platypus’s bill is soft and flexible. The surface of the platypus bill is packed with 40,000 electroreceptor which are arranged in rows along the length of the bill. Like the name suggests, electroreceptors are used to detect tiny bursts of electricity. In addition to electroreceptors, a platypus bill also has 60,000 mechanoreceptors. These are nerve endings that can detect small changes in pressure. When underwater, the platypus uses the electroreceptors to determine the location of prey by detecting the electricity produced when prey items contract their muscles. The mechanoreceptors are used to detect where their prey is moving underwater. Together, the electroreceptors and mechanoreceptors in the platypus bill help the platypus locate and zero in on its prey.

Genome Sequencing

In May 2008, a group of scientists announced that they had completed the genome sequencing for the platypus. The research, sponsored in part by the National Human Genome Research Institute associated with the National Institutes of Health, was led by scientists at the Washington University School of Medicine and included researchers from the United States, Australia, England, Germany, Israel, Japan, New Zealand, and Spain. The scientists studied the genome of a female platypus nicknamed “Glennie” from Glenrock Station, New South Wales, Australia. The results of the scientists’ research was published in the May 8, 2008 edition of the journal Nature.

Evolutionary Ancestors

In the study, the scientists compared the platypus genome with human, mouse, opossum, dog, and chicken genomes, as well as the draft green anole genome. They discovered that the platypus shares 82 percent of its genes with these animals. The scientists also found that platypuses share the same total amount of genes–approximately 18,500–that other mammals have.

Studying the platypus genome may help scientists determine when certain genes and traits specific to mammals may have emerged over time. (Photo Credit: ARCO/Mosebach K/age fotostock)

Characteristics such as egg-laying (females) and venomous spurs (males) were found to have origins in reptilian ancestors, although egg fertilization was found to have both reptilian and mammalian origins. Characteristics including fur, milk production (females), and a strong sense of smell were found to all be consistent with mammalian ancestors.


Researchers hope that by studying the platypus’s genome, they can determine when certain genes and traits specific to mammals, the class that includes humans, originated during evolutionary history. By comparing the platypus genome to the genomes of other mammals, scientists may be able to determine when certain traits were gained or lost over time.

More to Explore



  1. Very interesting article. I learned some new things about platypuses!(:

  2. Samantha Preece says

    This article opened my eyes to all the different abilities and traits that the platypus possess. Who would have known that they had a venom that was powerful enough to kill a large dog, but not powerful enough to injure a human.

    • Dalton Snyder says

      It’s truly amazing. You would think it’s just an innocent little animal.

    • Caroline Cassetty says

      Yeah, i wouldnt have guessed that. A platypus would have been the last animal in my mind to contain some type of venom. Who knew they had a shark like system to find their prey. I will never look at a platypus the same way again:)

    • Myla Schafer says

      Same for me. I never really gave it much thought to how they would defend themselves so i was suprised by the information about their bill and venom. The platypus is very unique.

    • Rob Donatucci says

      I agree. I never would’ve even thought that a platypus was venomous or could carry venom at all…

  3. Dalton Snyder says

    Wow! It amazes me to think that a platypus could have so many strange traits. But aside from the usual appearance being strange as it is, it seems like a usual animal as far as traits go, it would seem to be fairly normal. Not only was it shocking to be wrong there, but also about how defenseless it was. I would think such an animal would just be friendly and easy prey for lower animals, but the part about venom was sure to prove me wrong as well.

  4. Chris Nation says

    I find it interesting that both male and female are born with the spur even though only the males keep it. I wonder why this is?

    • Carly Waller says

      Maybe because the females have different hormones than the males and the hormones cause the female platypus to lose the spurs?

    • Camden Tammen says

      maybe the female doesn’t need it? I am not sure. but even if the male needed it wouldn’t the female need it too?

    • Oliver May says

      Males are typically more aggressive, and would probably carry a higher need for self-defense.

    • Mikki Davis says

      That is very interesting. Perhaps it has something to do with the males defending the females?

      • Mary Newton says

        Perhaps the females have the spur so they can defend themselves until there are bigger, then once they are mature they might not need it anymore?

  5. Carly Waller says

    I didn’t know that they had “spurs” in their hind legs that contains venom. I guess you learn something new everyday!

  6. Camden Tammen says

    I find it very interesting that the platypus shares so many of the same genes with other animals. it doesn’t resemble almost any of them

  7. sean oldroyd says

    its cool how the platypus lays eggs and its a mammal. I learned that it uses its bill underwater to track its pray.

    • Steven Goodpaster says

      It’s also pretty cool that its bill contains 40,000 electroreceptors and 60,000 mechanoreceptors!

  8. Myla Schafer says

    I was not aware of the major role that the platypus bill had. Things like nerve endings that can detect small changes in pressure and ectroreceptors to determine the location of prey, suprised me. The platypus is truly an amazing animal.

  9. Oliver May says

    To have such a diverse scale of traits is interesting. It makes you wonder how it came to that mixed form. Was it from mixed breeding, or possibly a variety of demanding environments.

  10. Don Zepecki says

    Certainly a dangerous mammal equipped with unique defensive mechanisms.

  11. Mikki Davis says

    I honestly never knew any of this about the platypus. Thanks for the great article! Very interesting that they’re not friendly.

  12. Emily Holder says

    Wow! It’s pretty amazing how we think we know so much of an animal, however we know so little. I never knew a platypus had venom or evens spur!

  13. Rachel Howard says

    I think it’s so cool that they close their eyes and ears when they go underwater and only rely on their bill to find prey. I wonder why ducks don’t do that?

  14. Mary Newton says

    I knew platypuses were unusual animals, but I never could have guessed they were poisonous or could find prey with electroreceptors and mechanoreceptors on their bills!

    • Spencer S. Sanders says

      I completely agree with you I was surprised too. I can’t believe they have all that on their bills, I would’ve never guessed that. Platypuses are more interesting than I thought and a cool topic as well.

  15. Kristen Gregory says

    It is amazing to know that a male platypus would be able to defend itself against a large dog using its spurs!

  16. Destiny White says

    I knew that platapuses were very unique, but I never knew they had venom. Very interesting!

  17. JoRya Cornett says

    I now know more about platypuses than ever before. Before I read this, all I knew about them was that they are the only mammals that lay eggs.

  18. Spencer S. Sanders says

    Wow that article was very interesting! I would have never guessed that male platypuses are so aggressive when it comes to mating. I’m also surprised that they have venom in a claw-like growth that they use to hurt other male platypuses.

  19. Heidy Orellana says

    It’s so strange to think that this animal has both reptilian and mammalian origins. I would have never thought it could have reptilian origins. This is one of the strangest creatures I have ever known about.

  20. Alexis Dupoux says

    I find it very interesting that the platypus has characteristics like that of a mammal and reptile. I also think that its fascinating how they have venom in a little spur on their hind legs.

  21. Katie Boniol says

    Platypuses are my new favorite animal, I find it truly amazing that they have so many interesting characteristics, especially how they lay eggs yet they are a mammal. I find these animals completely fascinating!

  22. Logan Augspurger says

    Pretty crazy that they can track their prey with their beak underwater, and I never would have thought that that they would carry venom. Definitely learned more about the platypus.

  23. Natalie Bondurant says

    The platypus is such an incredible and unique creature! Who knew it has electroreceptors to seek out its prey or that it has venom?

  24. Natalie Bondurant says

    It is very interesting. I have always thought that they would be very friendly animals.

  25. McKinzie Lilly says

    wow! I would of never thought there would be so many interesting facts about platypuses. people don’t realize that these animals are more unique then they look.

  26. Dawson Hutcherson says

    There’s a lot more to platypuses than I thought there was. I never stopped to actually think how unusual they are. Venomous spurs? They are more dangerous than I thought they were. Very interesting article, glad I read it!

  27. Austin Kirby says

    The way it uses electroreceptors and mechanoreceptors in its bill to detect prey is very intriguing. I’m curious as to which other animals have this capability.

  28. Colton Carver says

    I like platypuses

  29. Steven Goodpaster says

    I never would have thought that platypuses could carry poison in their spurs! I wonder why the females lose their spurs within the first year of their life.

  30. That truly is astonishing! Its like some sort of missing link between a variety of animals. With many different qualities compact into one organism this monotreme is very unique. The platypus is truly like no other.

  31. Rob Donatucci says

    Platypuses being able to carry poison is kinda… odd… Definitely stuck out to me.

    I guess this article shows that there’s still plenty to discover just on Planet Earth… I think everyone knows that already, though.

  32. Jacob West says

    Its amazing, the fact that a small animal could kill a large dog with its venom.

  33. Andy Scates says

    it is very interesting article make me want to learn more about the platypus

  34. Aline Stroud says

    I had no idea, Platypuses used their super-sensitive bill to detect prey when they are underwater. In fact, I didn’t know most of these facts about platypuses! Very interesting!

    • kaylie denney says

      i agree, I learned a lot of new facts about platypuses that i probably wouldn’t of ever known without reading this article.

  35. Cooper Wilson says

    I didn’t know that platypuses had spurs.

  36. Melissa Kelly says

    I understand why they close their ears, but I wonder how they do it.

  37. Cullen Dickerson says

    Well I never would have pictured a platypus dangerous or harmful to anything until now.

  38. Aline Stroud says

    I had no idea that platypuses used their super-sensitive bill to detect prey. In fact, I had no idea about any of these facts on platypuses! Very interesting!

  39. Emma Brown says

    Very interesting never thought platypuses could be poisonous always thought they were cute

  40. kaylie denney says

    I thought this was really interesting that platypuses had spurs, i probably wouldn’t of known that without this article.

  41. anthony pwnpwn says

    ya dis r very strange indead. da hale da hale

  42. This is a very unique animal that can do so many things. It helps you to know to be more careful around wildlife because you never know what they can do.

  43. There was nothing in here about them being secret agents.

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