Strange Animals01FACT“Scientists first thought it was a hoax.”WHERE IT CAME FROMThe 1799 specimen in Britain.
WHAT THE EVIDENCE SAYSGeorge Shaw described it, but checked the skin for stitches; some suspected a duck bill sewn on.
By Strange Animals · Updated 13 Nov 2026 · 14 sources
A mammal that lays eggs, hunts with its eyes shut by sensing electricity, and whose males carry venom. Found only in eastern Australia, it belongs to a branch of mammals that split from ours about 180 million years ago.
OrderMonotremata
Lives inEastern Australia, Tasmania
IUCN statusNear Threatened
DietInsect larvae, shrimp, worms
PLATYPUSES AT A GLANCE
The platypus (Ornithorhynchus anatinus) is one of five living monotremes, the egg-laying mammals; the other four are echidnas. It lives in rivers and streams of eastern Australia and Tasmania. It hunts underwater with its eyes, ears and nostrils closed, finding prey with electroreceptors and touch sensors in its bill. Females lay eggs and feed young with milk from skin patches, as they have no nipples. Males have a venomous spur on each hind leg. The species is listed as Near Threatened.
Figures graded and sourced in the fact sheet below.KEY DISCOVERIES
1799"A hoax"The first skin reaches Britain; George Shaw checks it for stitches, suspecting a fake.
1884Eggs confirmedWilliam Caldwell finds a platypus egg and telegraphs "Monotremes oviparous".
1986Electric senseResearchers show the bill detects weak electric fields from prey.
2004Ten sex chromosomesThe platypus is found to have five X and five Y chromosomes.
2008Genome sequencedIt mixes reptile, bird and mammal features (Warren et al.).
2020It glowsUnder UV light, platypus fur shines blue-green.
ONLY IN THE PLATYPUS
What makes the platypus unlike any other animal?
Short answer: It is the only animal that combines egg-laying, milk, electric sense and venom.
01A mammal that lays eggsOnly platypuses and echidnas do. Eggs are leathery, like a reptile’s, and hatch after about 10 days.Caldwell 1887
02Senses electricityAbout 40,000 electroreceptors in the bill detect the tiny currents from prey muscles.Scheich et al. 1986
03Venomous malesA spur on each hind ankle delivers venom that causes severe pain in people.Whittington & Belov 2014
04Ten sex chromosomesFive X and five Y, compared with our two.Grützner et al. 2004
05No stomachIts gullet joins straight to the intestine; the stomach was lost in evolution.Ordoñez et al. 2008
06Glows under UVIts fur shines blue-green under ultraviolet light, for reasons unknown.Anich et al. 2020
FACT SHEET
How big is a platypus?
Short answer: Smaller than most people expect: about 40 to 60 cm long including the tail, and under 2.5 kg.
MeasuredEstimatedQuoted, unverified
Length, incl. tailMeasured~40 to 60 cmMales~45 to 60 cmFemales~40 to 50 cmSize varies by region; largest in Tasmania
WeightMeasured~0.7 to 2.4 kgMalesup to ~2.4 kgFemalesup to ~1.6 kgMales are larger in all populations
ElectroreceptorsMeasured~40,000Electric~40,000Touch~60,000Spread in stripes along the bill. Manger & Pettigrew 1995
Body temperatureMeasured~32 °CPlatypus~32 °CHuman~37 °CLow for a mammal; saves energy in cold water
Eggs per clutchMeasured1 to 3Usual2Incubation~10 daysLaid in a sealed burrow; young suckle for 3 to 4 months
Typical diveMeasured~30 to 40 sTypical~30 to 40 sLongest~2 min+Dozens of dives per hour while foraging. Bethge et al. 2003
Daily foodEstimated~20% of body weightDaily intake~20%Can rise much higher for nursing females
Wild lifespanEstimatedup to ~24 yearsWild record~24 yrsTypical~10 yrs?From long-term tagging; typical lifespan is poorly known
Venom can kill a personQuoted, unverifiedn/aNo human death is recorded. The pain is severe and can last weeks; it can kill dogs.Common claim
THE BILL
How does a platypus find food with its eyes closed?
Short answer: Its soft, rubbery bill holds about 40,000 electroreceptors and 60,000 touch sensors, letting it locate prey by electric field and movement.
01Shut downUnderwater, flaps close over eyes, ears and nostrils.
02SweepIt swings its bill side to side along the riverbed, about twice a second.
03SenseElectroreceptors pick up muscle currents; touch sensors feel the pressure wave.
04StorePrey goes into cheek pouches, dive after dive.
05ChewAt the surface it grinds food between hard pads; adults have no teeth.
Not a duck’s billIt is soft, leathery skin full of nerves, not hard keratin like a bird’s beak.
Shared with echidnasEchidnas also have electroreceptors, but far fewer: about 400 to 2,000.
DistanceStrong signals are detected from about 10 to 20 cm away.
EGGS AND MILK
Do platypuses lay eggs and make milk?
Short answer: Yes, both. Females lay eggs in a burrow, then feed the hatchlings milk that seeps from patches on the belly, as they have no nipples.
PlatypusBirth1 to 3 leathery eggsIncubation~10 days, curled around themMilkFrom skin patches, no nipplesNurseryBurrow up to ~30 m long, plugged with soil
Most mammalsBirthLive youngIncubationPregnancy inside the bodyMilkFrom nipplesNurseryVaries
VENOM
Is the platypus venomous?
Short answer: The males are. A hollow spur on each hind ankle connects to a venom gland that swells in the breeding season, when males fight each other.
Only malesFemales are born with spur buds but lose them within the first year.
SeasonalVenom output peaks in the breeding season, from about June to October.
For peopleIntense pain that morphine barely helps, swelling, and sometimes weeks of sensitivity.
Over 80 toxinsSome venom genes evolved separately from similar ones in snakes and spiders.
BODY
How is a platypus built for the water?
Short answer: Dense waterproof fur, webbed front feet for paddling and a flat tail that stores fat.
FurTwo layers trap air and keep skin dry in cold water.
Folding websThe front webs fold back to reveal claws for digging burrows.
Fat tailStores up to about 40% of body fat, an energy reserve.
Lizard-like walkLegs sprawl out to the side, like a reptile’s, on land.
No adult teethYoung have tiny teeth; adults grind with keratin pads.
No stomachFood goes from gullet straight to intestine.
Cool bodyAbout 32 °C, lower than most mammals.
BiofluorescenceGlows blue-green under UV; purpose unknown.
EVOLUTION
Echidna: the spiny egg-laying mammal →Is the platypus a missing link between reptiles and mammals?
Short answer: No. It is a full mammal on its own branch. Monotremes kept some old features like egg-laying that other mammals lost.
Relationships only, not to time scale. After Warren et al. 2008 and Zhou et al. 2021. Echidna outline: PhyloPic, CC0.
THREATS AND CONSERVATION
Endangered register →Is the platypus endangered?
Short answer: Not yet. It is Near Threatened globally and Vulnerable in Victoria and Endangered in South Australia, and its habitat has shrunk by about 22% over the past 30 years.
Range and outlookRange lost~22%Range remaining~78%UNSW national assessment 2020, change since 1990. Drought plus land clearing could cut numbers by about half by 2070 (Bino et al. 2020).
Drought and damsHIGHRivers dry into pools; dams change flow and cut populations apart.
Nets and trapsHIGHEnclosed yabby traps drown platypuses; now banned in several states.
Foxes, dogs and litterMEDIUMPredators kill young; rubber bands and fishing line strangle adults.
Trap bansVictoria banned enclosed yabby traps in 2019, New South Wales in 2021.
eDNA surveysWater samples reveal platypus DNA, mapping where they still live.
River restorationReplanting banks and keeping water flowing in droughts.
Citizen sciencePublic sightings feed national platypus databases.
Seen a platypus?Report it. Sightings help map surviving populations.MYTH OR FACT
Six platypus claims, checked
2Myths1Half true3Facts
02MYTH“The platypus is part bird.”WHERE IT CAME FROMIts bill and eggs.
WHAT THE EVIDENCE SAYSIt is fully a mammal: fur, milk and mammal bones. The bill is soft skin, not a beak.
03MYTH“Platypus venom can kill a person.”WHERE IT CAME FROMIts venom spur.
WHAT THE EVIDENCE SAYSNo human deaths are recorded. It causes severe, long pain and can kill dogs.
04HALF TRUE“It is the only egg-laying mammal.”WHERE IT CAME FROMIts fame.
WHAT THE EVIDENCE SAYSEchidnas, four species, also lay eggs.
05FACT“Platypuses glow.”WHERE IT CAME FROMA 2020 museum study.
WHAT THE EVIDENCE SAYSTheir fur shines blue-green under ultraviolet light.
06FACT“Platypuses have no stomach.”WHERE IT CAME FROMAnatomy and genome studies.
WHAT THE EVIDENCE SAYSThe gullet joins straight to the intestine, and stomach genes are missing.
OPEN QUESTIONS
What science still doesn’t know
?Why glow?Biofluorescence was found in 2020; no function is known.
?How many are left?Estimates range from tens of thousands to a few hundred thousand.
?How long do they live?Typical wild lifespan is poorly known.
?What do the chromosomes do?How ten sex chromosomes pair and decide sex is still studied.
?Why lose the stomach?Possibly tied to diet, but the cause is debated.
?Can medicine use the venom?A hormone in the venom is being studied for diabetes treatments.
FAQ
Frequently asked questions
Is a platypus a mammal?+
Yes. It has fur and feeds its young milk, but it lays eggs. It is a monotreme.
Where do platypuses live?+
In rivers, streams and lakes of eastern Australia and Tasmania.
Are platypuses venomous?+
Males have a venomous spur on each hind leg. The venom is very painful to people but not known to be deadly.
Do platypuses lay eggs?+
Yes. Females lay 1 to 3 leathery eggs in a burrow and incubate them for about 10 days.
How does a platypus find food?+
With its eyes, ears and nostrils closed, using electroreceptors and touch sensors in its bill.
Are platypuses endangered?+
They are Near Threatened worldwide and listed as threatened in Victoria and South Australia.
COMPARE AND EXPLORE
Explore platypuses further
HOW WE KNOW
Sources and how we check
This page is written by Strange Animals and checked against primary research. Every figure carries a grade and a numbered source.
Cite this pageStrange Animals. (2026, November 13). Platypus (Ornithorhynchus anatinus): eggs, electric sense, venom and evolution. https://strangeanimals.info/mammals/monotremes/platypus
- 01Grützner, F. et al. In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes. Nature 432: 913-9172004
- 02Warren, W. C. et al. Genome analysis of the platypus reveals unique signatures of evolution. Nature 453: 175-1832008
- 03Zhou, Y. et al. Platypus and echidna genomes reveal mammalian biology and evolution. Nature 592: 756-7622021
- 04Scheich, H. et al. Electroreception and electrolocation in platypus. Nature 319: 401-4021986
- 05Manger, P. R. and Pettigrew, J. D. Electroreception and the feeding behaviour of platypus. Philosophical Transactions of the Royal Society B 3471995
- 06Whittington, C. M. and Belov, K. Tracing monotreme venom evolution in the genomics era. Toxins 6: 1260-12732014
- 07Anich, P. S. et al. Biofluorescence in the platypus. Mammalia 85: 179-1812020
- 08Bino, G. et al. The platypus: evolutionary history, biology, and an uncertain future. Journal of Mammalogy 100: 308-3272019
- 09Hawke, T., Bino, G. and Kingsford, R. T. A silent demise: historical insights into population changes of the iconic platypus. Global Ecology and Conservation 202019
- 10Bino, G., Kingsford, R. T. and Wintle, B. A. A stitch in time: synergistic impacts to platypus metapopulation extinction risk. Biological Conservation 2422020
- 11Woinarski, J. and Burbidge, A. A. Ornithorhynchus anatinus. IUCN Red List. Near Threatened2016
- 12Bethge, P. et al. Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus. Comparative Biochemistry and Physiology A 136: 799-8092003
- 13Shaw, G. The duck-billed platypus. The Naturalist’s Miscellany 101799
- 14Grant, T. and Fanning, D. Platypus, 4th edition. CSIRO Publishing2007
WATCH
Three films worth your time
Animated lessonTED-Ed · Gilad BinoA year in the life of one of Earth’s weirdest animalsDrought, electric hunting, venom and the burrow, told by a platypus researcher.Pairs with: The bill →
ClipBBC EarthKingfisher and Platypus Hunt TogetherA kingfisher follows a foraging platypus to catch what it disturbs.Pairs with: Body →
ClipBBC EarthThis Platypus Can Glow in the Dark!The 2020 discovery that platypus fur glows under UV light.Pairs with: Open questions →
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