Editing Platypus (section)

==Distribution, ecology, and behaviour==
[[File:Animaldentition ornithoryncusanatinus.png|thumb|Dentition, as illustrated in Knight's ''Sketches in Natural History'']]
[[File:Ornithorhynchus anatinus -Sydney Aquarium, Sydney, Australia -swimming-6a.ogv|thumbtime=50|right|thumb|Swimming underwater at [[Sydney Aquarium]], Australia]]

The platypus is semiaquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of [[Tasmania]] and the [[Australian Alps]] to the [[tropical rainforest]]s of coastal [[Queensland]] as far north as the base of the [[Cape York Peninsula]].<ref name="DPIW">{{cite web|url=http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open |title=Platypus |publisher=Department of Primary Industries and Water, Tasmania |date=31 August 2006 |access-date=12 October 2006 |url-status=dead |archive-url=https://web.archive.org/web/20061009211345/http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open |archive-date= 9 October 2006 }}</ref>

Inland, its distribution is not well known. It was considered extinct on the [[South Australia]]n mainland, with the last sighting recorded at [[Renmark, South Australia|Renmark]] in 1975.<ref name="Sutton">{{cite web | last=Sutton | first=Malcolm | title=Platypus 'sighting' in the Adelaide Hills sparks camera set-up to capture extinct species - ABC News | website=ABC (Australian Broadcasting Corporation) | date=3 May 2017 | url=https://www.abc.net.au/news/2017-05-04/cameras-set-up-to-confirm-platypus-sighting-in-adelaide-hills/8492400 | access-date=12 October 2020 | archive-date=26 November 2020 | archive-url=https://web.archive.org/web/20201126044708/https://www.abc.net.au/news/2017-05-04/cameras-set-up-to-confirm-platypus-sighting-in-adelaide-hills/8492400 | url-status=live }}</ref> In the 1980s, [[John Wamsley]] created a platypus breeding program in [[Warrawong Sanctuary]] (see [[#Platypus in wildlife sanctuaries|below]]), which subsequently closed.<ref>{{cite web | title=Life reinstated to much-loved Warrawong Wildlife Sanctuary | first=Melissa | last=Keogh | website=The Lead SA | date=3 October 2018 | url=http://theleadsouthaustralia.com.au/industries/regional-showcase/life-reinstated-to-much-loved-warrawong-wildlife-sanctuary/ | access-date=12 October 2020 | archive-date=12 October 2020 | archive-url=https://web.archive.org/web/20201012171044/http://theleadsouthaustralia.com.au/industries/regional-showcase/life-reinstated-to-much-loved-warrawong-wildlife-sanctuary/ | url-status=live }}</ref><ref>{{cite news|last=Adams|first=Prue|title=Wamsley walks away from Earth Sanctuaries|work=Landline|publisher=Australian Broadcasting Corporation|url=https://www.abc.net.au/local/archives/landline/content/2005/s1330004.htm|date=27 March 2005|access-date=12 October 2020|archive-date=12 October 2020|archive-url=https://web.archive.org/web/20201012103440/https://www.abc.net.au/local/archives/landline/content/2005/s1330004.htm|url-status=live}}</ref> In 2017 there were some unconfirmed sightings downstream from the sanctuary,<ref name="Sutton"/> and in October 2020 a nesting platypus was filmed inside the recently reopened sanctuary.<ref name="Sutton 2020">{{cite web | last=Sutton | first=Malcolm | title=V6 Commodore water pump gets the tick from nesting platypus at Warrawong | website=ABC News | publisher=Australian Broadcasting Corporation | date=1 October 2020 | url=https://www.abc.net.au/news/2020-10-02/playtpus-nesting-in-restored-swamp-at-warrawong/12719346 | access-date=7 October 2020 | archive-date=7 October 2020 | archive-url=https://web.archive.org/web/20201007035918/https://www.abc.net.au/news/2020-10-02/playtpus-nesting-in-restored-swamp-at-warrawong/12719346 | url-status=live }}</ref>

There is a population on [[Kangaroo Island]]<ref name="RKI">{{cite web|url=http://www.ees.adelaide.edu.au/research/fbp/ki_res/|archive-url=https://web.archive.org/web/20040706181309/http://www.ees.adelaide.edu.au/research/fbp/ki_res/|url-status=dead|archive-date=6 July 2004|title=Research on Kangaroo Island|publisher=University of Adelaide|date=4 July 2006| access-date = 23 October 2006}}</ref> introduced in the 1920s, said to stand at 150 individuals in the Rocky River region of [[Flinders Chase National Park]]. In the [[2019–20 Australian bushfire season]], large portions of the island burnt, decimating wildlife. However, [[Department for Environment and Water (South Australia)|SA Department for Environment and Water]] recovery teams worked to reinstate their habitat, with a number of sightings reported by April 2020.<ref>{{cite web | title=Find out how platypuses are faring on Kangaroo Island following the bushfires | website=Department for Environment and Water | date=7 April 2020 | url=https://www.environment.sa.gov.au/goodliving/posts/2020/04/platypus-recovery-on-ki | access-date=12 October 2020 | archive-date=21 July 2021 | archive-url=https://web.archive.org/web/20210721003955/https://www.environment.sa.gov.au/goodliving/posts/2020/04/platypus-recovery-on-ki | url-status=live }}</ref>

The platypus is no longer found in the main [[Murray–Darling basin|Murray–Darling Basin]], possibly due to declining [[water quality]] from land clearing and [[irrigation]]<ref name="CSIRO">{{cite web|url=http://www.clw.csiro.au/publications/technical97/tr23-97.pdf|title=Impacts of water management in the Murray-Darling Basin on the platypus (''Ornithorhynchus anatinus'') and the water rat (''Hydromus chrysogaster'')|author1=Scott, Anthony|author2=Grant, Tom|publisher=CSIRO Australia|date=November 1997|access-date=23 October 2006|archive-date=15 March 2016|archive-url=https://web.archive.org/web/20160315115754/http://www.clw.csiro.au/publications/technical97/tr23-97.pdf|url-status=live}}</ref> although it is found in the [[Goulburn River]] in Victoria.<ref>{{cite web|url=https://platypus.asn.au/platypus-burrows/ |title=Platypus burrows |website=Australian Platypus Conservancy|date=6 March 2024 }}</ref> Along the coastal river systems, its distribution is unpredictable: absent in some relatively healthy rivers, but present in some quite degraded ones, for example the lower [[Maribyrnong River|Maribyrnong]].<ref name="APC2">{{cite web|url=http://www.platypus.asn.au/platypus_in_country_areas.html |archive-url=https://web.archive.org/web/20160917002720/http://www.platypus.asn.au/platypus_in_country_areas.html |archive-date=17 September 2016 |title=Platypus in Country Areas |publisher=Australian Platypus Conservancy |access-date=23 October 2006 |url-status=dead }}</ref>

In captivity, platypuses have survived to 30 years of age, and wild specimens have been recaptured when 24 years old. [[Mortality rate]]s for adults in the wild appear to be low.<ref>{{cite news|title=Oldest-known wild platypus gives new insights into longevity of enigmatic Australian species|website=ABC Science |author=Peter de Kruijff|url=https://www.abc.net.au/news/science/2024-02-15/new-platypus-age-records-for-captive-and-wild-specimens/103450732|date=14 February 2024}}</ref> Natural predators include [[snake]]s, [[Rakali|water rats]], [[goanna]]s, [[hawk]]s, [[owl]]s, and [[eagle]]s. Low platypus numbers in northern Australia are possibly due to predation by [[crocodile]]s.<ref name="EPA">{{cite web|url=http://www.epa.qld.gov.au/nature_conservation/wildlife/az_of_animals/platypus.html |title=Platypus |publisher=Environmental Protection Agency/Queensland Parks and Wildlife Service |year=2006 |access-date=24 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20091021042522/http://www.epa.qld.gov.au/nature_conservation/wildlife/az_of_animals/platypus.html |archive-date=21 October 2009 }}</ref> The introduction of [[red fox]]es in 1845 for sport hunting may have had some impact on its numbers on the mainland.<ref name="Workshop" /> The platypus is generally [[nocturnal]] and [[crepuscular]], but can be active on overcast days.<ref name="EC">{{cite web|url=http://www.biology.iastate.edu/InternationalTrips/1Australia/04papers/CromerMonotrRepro.htm |title=Monotreme Reproductive Biology and Behavior |publisher=Iowa State University |author=Cromer, Erica |date=14 April 2004 |access-date=18 June 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090313030236/http://www.biology.iastate.edu/InternationalTrips/1Australia/04papers/CromerMonotrRepro.htm |archive-date=13 March 2009 }}</ref><ref name="HCP">{{cite journal|journal=Philosophical Transactions: Biological Sciences|title=Field biology of the platypus (''Ornithorhynchus anatinus''): historical and current perspectives|volume=353|issue=1372|author=Grant, T.G.|author2= Temple-Smith, P.D. |year=1998|pmid=9720106|pages=1081–91|pmc=1692311 | doi = 10.1098/rstb.1998.0267}}</ref> Its habitat bridges [[river]]s and the [[riparian zone]], where it finds both prey and river banks to dig resting and nesting burrows.<ref name="HCP" /> It may have a range of up to {{convert|7|km|mi|abbr=on}}, with a male's home range overlapping those of three or four females.<ref name="AJZ4">{{cite journal|journal=Australian Journal of Zoology|title=Spatial-Organization and Movement Patterns of Adult Male Platypus, ''Ornithorhynchus anatinus'' (Monotremata, Ornithorhynchidae) |volume=43 |issue=1 |author= Gardner, J. L. |author2=Serena, M. |year=1995 |pages=91–103 | doi = 10.1071/ZO9950091
}}</ref>

The platypus is an excellent swimmer and spends much of its time in the water foraging for food. It has a swimming style unique among mammals,<ref name="dpipwe">{{cite web|url=https://dpipwe.tas.gov.au/wildlife-management/fauna-of-tasmania/mammals/echidnas-and-platypus/platypus/platypus-in-tasmania|title=Platypus in Tasmania {{!}} Department of Primary Industries, Parks, Water and Environment, Tasmania|website=dpipwe.tas.gov.au|access-date=10 April 2020|archive-date=8 March 2020|archive-url=https://web.archive.org/web/20200308221910/https://dpipwe.tas.gov.au/wildlife-management/fauna-of-tasmania/mammals/echidnas-and-platypus/platypus/platypus-in-tasmania|url-status=live}}</ref> propelling itself by alternate strokes of the front feet, while the webbed hind feet are held against the body and only used for steering, along with the tail.<ref name="Rowing">{{cite journal|journal=The Journal of Experimental Biology|volume=200|issue=20|pages=2647–52|title=Energetics of Swimming by the Platypus ''Ornithorhynchus anatinus'': Metabolic Effort Associated with Rowing|author=Fish, F.E.|author2=Baudinette, R.V.|author3=Frappell, P.B.|author4=Sarre, M.P.|year=1997|doi=10.1242/jeb.200.20.2647|url=http://jeb.biologists.org/cgi/reprint/200/20/2647.pdf|pmid=9359371|bibcode=1997JExpB.200.2647F |access-date=23 October 2006|archive-date=26 September 2009|archive-url=https://web.archive.org/web/20090926191559/http://jeb.biologists.org/cgi/reprint/200/20/2647.pdf|url-status=live}}</ref> It can maintain its relatively low body temperature of about 32{{spaces}}°C (90{{spaces}}°F) while foraging for hours in water below 5{{spaces}}°C (41{{spaces}}°F).<ref name="ABRS" /> Dives normally last around 30 seconds, with an estimated aerobic limit of 40 seconds, with 10 to 20 seconds at the surface between dives.<ref name="Bethge">{{cite thesis|url=http://eprints.utas.edu.au/2326/|title=Energetics and foraging behaviour of the platypus|publisher=University of Tasmania|author=Philip Bethge|date=April 2002|doi=10.25959/23210588.v1 |access-date=21 June 2009|archive-date=25 October 2018|archive-url=https://web.archive.org/web/20181025070921/https://eprints.utas.edu.au/2326/|type=thesis |url-status=live}}</ref><ref>{{cite journal|journal=The Journal of Applied Ecology|jstor=2404239|title=The Diving Behaviour of the Platypus (''Ornithorhynchus anatinus'') in Waters with Different Trophic Status|author=Kruuk, H. |volume=30|issue=4|year=1993|pages=592–8 | doi = 10.2307/2404239|bibcode=1993JApEc..30..592K }}</ref>

The platypus rests in a short, straight burrow in the riverbank about {{convert|30|cm|in|0|abbr=on}} above water level, its oval entrance-hole often [[Camouflage|hidden]] under a tangle of roots.<ref name="dpipwe" /> It may sleep up to 14 hours per day, after half a day of diving.<ref>{{cite journal |author=Holland, Jennifer S. |title=40 Winks? |journal= National Geographic|volume=220 |issue=1 |date=July 2011 }}</ref>

=== Diet ===
The platypus is a [[carnivore]], feeding on [[annelid]] worms, [[Larva|insect larvae]], freshwater [[shrimp]], and [[Cherax|yabby]] ([[crayfish]]) that it digs out of the riverbed with its snout or catches while swimming. It carries prey to the surface in cheek-pouches before eating it.<ref name="dpipwe" /> It eats about 20% of its own weight each day, which requires it to spend an average of 12 hours daily looking for food.<ref name="Bethge" />

=== Reproduction ===
[[File:Ornithorhynchus anatinus - nest with eggs - MUSE.JPG|thumb|Platypus's nest with eggs (replica)]]

The species has a single [[breeding season]] between June and October, with some local variation.<ref name="EPA" /> Investigations have found both resident and transient platypuses, and suggest a [[Polygyny in animals|polygynous]] mating system.<ref name="AJZ2">{{cite journal|journal=Australian Journal of Zoology|title=Aspects of Lactation in the Platypus, ''Ornithorhynchus anatinus'' (Monotremata), in Waters of Eastern New South Wales|author=Grant, T. R. |author2=Griffiths, M. |author3=Leckie, R.M.C. |volume=31|issue=6|pages=881–9|doi=10.1071/ZO9830881|year=1983}}</ref> Females are believed to become sexually mature in their second year, with breeding observed in animals over nine years old.<ref name="AJZ2"/> During [[Copulation (zoology)|copulation]], the male grasps the female's tail with his bill, wraps his tail around her, then grips her neck or shoulder, everts his [[penis]] through his [[cloaca]], and inserts it into her [[urogenital sinus]].<ref>{{Cite book |last=Grant |first=Tom |url=https://books.google.com/books?id=bu8rIm-TdqwC&dq=platypus+copulation&pg=PA17 |title=Platypus |date=2007-10-02 |publisher=Csiro Publishing |isbn=978-0-643-10127-2 |language=en}}</ref> He takes no part in nesting, living in his year-long resting burrow. After mating, the female constructs a deep, elaborate nesting burrow up to {{convert|20|m|ft|round=5|abbr=on}} long.<ref name="ADW">{{cite web |url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Ornithorhynchidae.html |title=Family Ornithorhynchidae (platypus) |author1=Anna Bess Sorin |author2=Phil Myers |name-list-style=amp |publisher=University of Michigan Museum of Zoology |year=2001 |access-date=24 October 2006 |archive-date=10 April 2011 |archive-url=https://web.archive.org/web/20110410142645/http://animaldiversity.ummz.umich.edu/site/accounts/information/Ornithorhynchidae.html |url-status=live }}</ref> She tucks fallen leaves and reeds underneath her curled tail, dragging them to the burrow to soften the tunnel floor with folded wet leaves, and to line the nest at the end with bedding.<ref name="APC" />

The male platypus has [[penile spines]] and an asymmetrical [[glans penis]], with the right side smaller than the left.<ref>{{Cite book |last1=Vogelnest |first1=Larry |url=https://books.google.com/books?id=4d6VDwAAQBAJ&dq=platypus&pg=PA64 |title=Current Therapy in Medicine of Australian Mammals |last2=Portas |first2=Timothy |date=2019-05-01 |publisher=Csiro Publishing |isbn=978-1-4863-0752-4 |language=en}}</ref> The female has two [[Ovary|ovaries]], but only the left one is functional.<ref>{{Cite book |last1=Vogelnest |first1=Larry |url=https://books.google.com/books?id=p8cDEAAAQBAJ&pg=PA107 |title=Medicine of Australian Mammals |last2=Woods |first2=Rupert |date=18 August 2008 |publisher=Csiro Publishing |isbn=978-0-643-09797-1 |language=en |access-date=27 April 2024 |archive-date=25 May 2024 |archive-url=https://web.archive.org/web/20240525044226/https://books.google.com/books?id=p8cDEAAAQBAJ&pg=PA107#v=onepage&q&f=false |url-status=live }}</ref><ref name="EC" /> She lays one to three (usually two) small, leathery eggs (similar to those of reptiles), about {{convert|11|mm|in|frac=32|abbr=on}} in diameter and slightly rounder than bird eggs.<ref name="BSED">{{cite journal|journal= Philosophical Transactions of the Royal Society B: Biological Sciences|title=Early development and embryology of the platypus|author=Hughes, R. L. |author2=Hall, L. S. |volume=353|issue=1372|pages=1101–14|date=28 July 1998|pmid= 9720108|pmc= 1692305 | doi = 10.1098/rstb.1998.0269}}</ref> The eggs develop ''[[Uterus|in utero]]'' for about 28 days, with only about 10 days of external [[Avian incubation|incubation]] (in contrast to a chicken egg, which spends about one day in tract and 21 days externally).<ref name="EC" /> The female curls around the incubating eggs, which develop in three phases.<ref name="RS2" /> In the first, the [[embryo]] has no functional organs and relies on the [[yolk sac]] for sustenance, until the sac is absorbed.<ref>{{cite web|title=Ockhams Razor|work=The Puzzling Platypus|url=http://www.abc.net.au/radionational/programs/ockhamsrazor/the-puzzling-platypus/3492688|access-date=2 December 2006|date=20 July 2001|archive-date=9 August 2017|archive-url=https://web.archive.org/web/20170809103030/http://www.abc.net.au/radionational/programs/ockhamsrazor/the-puzzling-platypus/3492688|url-status=live}}</ref> During the second phase, the digits develop, and in the last phase, the [[egg tooth]] appears.<ref name="RS2">{{cite journal|journal=Philosophical Transactions: Biological Sciences|title =The development of the external features of the platypus (''Ornithorhynchus anatinus'')|author=Manger, Paul R. |author2=Hall, Leslie S. |author3=Pettigrew, John D. |volume=353|issue=1372|pages=1115–25|date=29 July 1998|pmid=9720109|pmc=1692310|doi =10.1098/rstb.1998.0270}}</ref> At first, European [[natural history|naturalists]] could hardly believe that the female platypus lays eggs, but this was finally confirmed by [[William Hay Caldwell]] in 1884.<!--for wiring London and other such trivia see that article--><ref name="ABRS"/><ref name="PS"/>

Most mammal zygotes go through [[holoblastic]] cleavage, splitting into multiple divisible daughter cells. However, [[monotremes]] like the platypus, along with [[Sauropsida|reptiles and birds]], undergo meroblastic cleavage, in which the ovum does not split completely. The cells at the edge of the yolk remain continuous with the egg's cytoplasm, allowing the yolk and embryo to exchange waste and nutrients with the egg through the cytoplasm.<ref>{{cite journal|author=Myers, P. Z.|url=http://www.nature.com/scitable/topicpage/interpreting-shared-characteristics-the-platypus-genome-44568|title=Interpreting Shared Characteristics: The Platypus Genome|journal=Nature Education|volume=1|issue=1|page=462008|year=2008|access-date=26 March 2015|archive-date=4 March 2018|archive-url=https://web.archive.org/web/20180304124410/http://www.nature.com/scitable/topicpage/interpreting-shared-characteristics-the-platypus-genome-44568|url-status=live}}</ref>

Young platypus are called "puggles". Newly hatched platypuses are vulnerable, blind, and hairless, and are fed by the mother's milk, that provides all the requirements for growth and development.<ref>{{cite web|last1=Stannard|first1=Hayley J.|last2=Old|first2=Julie M.|title=Wallaby joeys and platypus puggles are tiny and undeveloped when born. But their mother's milk is near-magical|url=https://theconversation.com/wallaby-joeys-and-platypus-puggles-are-tiny-and-undeveloped-when-born-but-their-mothers-milk-is-near-magical-207726|publisher=The Conversation|year=2023|access-date=25 October 2023|archive-date=10 November 2023|archive-url=https://web.archive.org/web/20231110202925/https://theconversation.com/wallaby-joeys-and-platypus-puggles-are-tiny-and-undeveloped-when-born-but-their-mothers-milk-is-near-magical-207726|url-status=live}}</ref><ref>{{cite journal|last1=Stannard|first1=Hayley J.|last2=Miller|first2=Robert D.|last3=Old|first3=Julie M.|title=Marsupial and monotreme milk – a review of its nutrients and immune properties|journal=PeerJ|year=2020|volume=8|page=e9335|doi=10.7717/peerj.9335 |pmid=32612884 |pmc=7319036 |doi-access=free }}</ref> The platypus's [[mammary gland]]s lack [[teat]]s, with milk released through pores in the skin. The milk pools in grooves on the mother's abdomen, allowing the young to lap it up.<ref name="APC" /><ref name="EPA" /> After they hatch, the offspring are milk-fed for three to four months.

During incubation and weaning, the mother initially leaves the burrow only for short periods to forage. She leaves behind her a number of thin soil plugs along the length of the burrow, possibly to protect the young from predators; pushing past these on her return squeezes water from her fur and allows the burrow to remain dry.<ref name="QM">{{cite web|url=http://www.qm.qld.gov.au/inquiry/factsheets/leaflet0010.pdf|title=Egg-laying mammals|publisher=Queensland Museum|date=November 2000| access-date = 19 June 2009|archive-url = https://web.archive.org/web/20080722180447/http://www.qm.qld.gov.au/inquiry/factsheets/leaflet0010.pdf |archive-date = 22 July 2008|url-status=dead}}</ref> After about five weeks, the mother begins to spend more time away from her young, and at around four months, the young emerge from the burrow.<ref name="EPA" /> A platypus is born with teeth, but these drop out at a very early age, leaving the horny plates it uses to grind food.<ref name="Piper-2007">{{cite book |author-link=Ross Piper |first=Ross |last=Piper |title=Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals |url=https://archive.org/details/extraordinaryani0000pipe |url-access=registration |publisher=[[Greenwood Press (publisher)|Greenwood Press]] |year=2007 |isbn=978-0-313-33922-6 }}</ref>