
:''This article is about the mammal. For the genus see ambrosia beetle.''
The platypus (''Ornithorhynchus anatinus'') is a small, semi-aquatic mammal endemic (ecology) to the eastern part of Australia, and one of the four extant monotremes, the only mammals that lay egg (biology) instead of giving birth to live young (the other three are echidnas). It is the sole representative of its family (biology) (''Ornithorhynchidae'') and genus (''Ornithorhynchus''), though a number of Monotreme#Fossil Monotremes have been found, some of them also in the ''Ornithorhynchus'' genus. The platypus is considered one of the strangest specimens of the animal kingdom: a venomous, egg-laying, duck-billed mammal. == Physiology and anatomy == The platypus' metabolic rate is remarkably low compared to other mammals, with a body temperature averaging 32°Celsius (90°Fahrenheit) rather than the 38°C (100.4°F) typical of placentalia. The extent to which this is a characteristic of monotremes, as opposed to an adaptation on the part of the small number of surviving species to harsh environmental conditions, is uncertain. The body and the broad, flat tail of the platypus are covered with brown fur. It has webbed feet and a large, rubbery snout that are more reminiscent of a duck's features than those of any known mammal. Weight varies considerably between less than a kilogram (two Pound#Pound (avoirdupois) or international pounds) and over two kilograms (just under four and one half pounds); with body length ranging from 30 to 40 centimetre (nearly 1Foot (unit of length) to 1'3inch), and tail length from 10 to 15 cm (4" to 6") for males and 8 to 13 cm (3" to 5") for females. Males are around one-third larger than females. There is substantial variation in average size from one region to another, though oddly this pattern does not seem to follow any particular climate rule. Modern platypus young have ''tribosphenic molar'' (three-cusped) molar (tooth)s, which are one of the hallmarks of mammals; adults are toothless. The platypus jaw is constructed somewhat differently from that of other mammals, and the jaw opening muscle is different. As in all true mammals, the tiny bones that conduct sound to the inner ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other pre-mammalian synapsids. However, the external opening of the ear still lies at the base of the jaw. The platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals. It also has a reptile-like gait, with legs that are on the sides of rather than underneath the body. The male platypus has venomous ankle spurs, used in vicious territorial battles and fights over mates. The poison is not lethal to humans but produces excruciating pain and inflammation that may last for several months. The venom can be lethal to dogs and smaller domestic animals. The male platypus reproductive structure is much like that of other mammals. One exception is that their testicles are inside their body, near their kidneys. The female reproductive system, on the other hand, differs from other placental mammals. Their paired ovaries resemble those of birds and reptiles. Although the platypus has two separate ovaries, only the left one is functional. The other is primitive and underdeveloped, and does not produce eggs. == Reproduction == ===Courtship=== The platypus’ behavior before mating is complex but relatively undocumented. The breeding season is in the late winter to early spring, which in Australia is August to November. A male will mate with any number of females during this time, for the platypus does not form life-long mates. Few platypuses have been seen mating, but courtship has been recorded to involve the male chasing and circling the female and biting her tail. Platypus are usually solitary animals, but during courtship, bodily contact between the pair is increased. During mating, the male curls his tail beneath the female, and lays his chest on the female’s back. There have been about five different recorded courtship methods. The first involves the male resting on the water, and the female swimming over to him and resting her muzzle on his. The second included the female swimming to the male and rubbing his side. The third recorded the female swimming beneath the male upside down, while rubbing his abdomen. The fourth documented the female swimming underneath the male and surfacing behind him. Finally, the fifth recorded instance included the female and male circling one another in tight circles. ===Development/Gestation=== Platypuses lay small, leathery eggs similar to those of reptiles, which are slightly rounder than bird eggs. Females usually lay two eggs at a time, but sometimes they lay one egg or three, which are about 1and 1/7 cm in diameter. The incubation period is separated into three parts . In the first, the embryo has no functional organs and relies on the yolk sac for respiration. During the second, the fingers and toes appear, and in the last, the egg tooth appears. ===Parental Investment=== Outside the mating season, platypuses live in simple burrows in the ground. After mating, though, the female constructs a deeper, more elaborate burrow, while the male takes no part in caring for its young, and retreats to its yearlong burrow. The new nesting burrow that females dig may be as long as 85 feet. The burrow's entrance is about one foot above the water. The female softens the ground in the burrow with dead, folded, wet leaves. After the eggs hatch, the mother only leaves the burrow for short periods of time to feed and wet her fur. When the mother leaves her young, she plugs the entrance with soil to protect her offspring. After laying her eggs, the female curls around them. The newly hatched platypuses are vulnerable, blind, and nude, and are fed by the mother's milk. Although she does not have nipples, the milk is released through pores in her abdomen. There are grooves on her abdomen that form pools of milk, allowing the young platypuses to lap up the milk. The offspring are suckled for three to four months after they have hatched. They leave the burrow when they are seventeen weeks old. == Platypus venom == Venom is produced in the crural glands of the male during the breeding season and is aggressively inflicted through a calcaneous spur on each hind limb. Because the venom appears to have a different function from venoms produced by non-mammalian species, it may contain peptides or molecules whose principal effects are non-life threatening but nevertheless may seriously impair the victim. That this could be the case is evident from the symptoms of platypus envenomation. In humans the most remarkable symptom is immediate and excruciating pain. Edema rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from case study and anecdotal evidence indicates that the pain develops into a long-lasting hyperalgesia that persists for days or even months. == Ecology and behaviour == The platypus is nocturnal and semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula. Inland, its distribution is not well known: it is extinct in South Australia (bar an introduced population on Kangaroo Island) and is no longer found in the main part of the Murray-Darling Basin, probably because of the declining water quality brought about by extensive land clearing and irrigation schemes. Along the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower Maribyrnong_River, for example). The platypus is an excellent swimmer and spends much of its time in the water. When swimming they are distinguished from other Australian mammals by the absence of visible ears. It keeps its eyes tightly shut when swimming, relying completely on its other senses. All four feet of the platypus are webbed. When it swims, it propels itself by paddling with the front two feet. The tail and hind feet assist in steering but not propulsion. The platypus is a carnivore. It feeds on worms and larva, freshwater shrimps, and yabbies (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. Its bill is very sensitive, allowing it to hunt its food without using sight. It is one of the few mammals known to have a sense of Electroception: it locates its prey in part by detecting their body electricity. Its electroception is the most sensitive of any mammal. This is discussed in more detail below. When not in the water, the platypus retires to a short, straight burrow of oval cross-section, nearly always in the riverbank not far above water level, and often camouflage under a protective tangle of roots. For breeding, the female digs much larger and more elaborate burrows, up to 20 metre long and blocked with plugs at intervals. She fills the nest at the end of the tunnel with reeds for bedding material. As a monotreme, the platypus does not give birth to live young but instead lays eggs in its burrow. During the mating season, the female builds a nest of leaves and grass at the end of her burrow, located in the banks of streams. Before laying her eggs, she blocks the entrances to the burrow with dirt. Female platypuses lay one to three eggs at a time. The eggs are retained in the body for some time before they are laid and cared for actively by the parent. When the eggs hatch after an incubate period of roughly ten days, the small hairless babies cling to the mother. Like other mammals, the mother produces milk for the young. The platypus does not have nipples, but excretes the milk through pores in her skin. The young suckle milk off the mother's belly while she lies on her back. == Electrolocation in the platypus == In the platypus, receptor (biochemistry) are located in rostro-caudal rows in the skin of the bill, while mechanoreceptors are uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals. The platypus feeds by digging in the bottom of streams with the bill. In this situation, the electroreceptors could also be used to distinguish animate and inanimate objects in this situation (where the mechanoreceptors would be continuously stimulated). Much of this is speculation, and there is still much to be learned about electroreception in the platypus and its fellow monotreme, the echidna. == Field biology of the platypus == The field biology of the platypus was first studied by a number of expatriate biologists who visited the Australian colonies to collect specimens in the 1800s. Their work was followed in the early to mid-1900s by a group of resident natural historians and later by an increasing number of academic biologists. All of these workers contributed significantly to the current understanding of the field biology of this unique Australian species. The platypus occupies much the same general distribution as it did prior to European occupation of Australia, except for its loss from the state of South Australia. However, local changes and fragmentation of distribution due to human modification of its habitat are documented. The species currently inhabits eastern Australia from around Cooktown in the north to Tasmania in the south. Although not found in the west-flowing rivers of northern Queensland, it inhabits the upper reaches of rivers flowing to the west and north of the dividing ranges in the south of the state and in New South Wales and Victoria. Its current and historical abundance, however, is less well known and it has probably declined in numbers, although still being considered as common over most of its current range. The species was extensively hunted for its fur until around the turn of the 20th century. The platypus is mostly nocturnal in its foraging activities, being predominantly an opportunistic carnivore of benthic invertebrates. The species is endothermic, maintaining its low body temperature (32°C), even while foraging for hours in water below 5°C. Its major habitat requirements include both riverine and riparian features which maintain a supply of benthic prey species and consolidated banks into which resting and nesting burrows can be excavated. The species exhibits a single breeding season, with mating occurring in late Winter or Spring (season) and young first emerging into the water after 3-4 months of nurture by the lactating females in the nesting burrows. Natural history observations, mark and recapture studies and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a polygyny mating system. Recent field studies have largely confirmed and extended the work of the early biologists and natural historians. == Scientific history == When the platypus was first discovered by Europeans in the late 1700s, a pelt was sent back to Britain for examination by the scientific community. The British scientists were at first convinced that the seemingly odd collection of physical attributes must be a hoax, produced by some Asian taxidermy. It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Scientists were also divided over whether the female platypus laid eggs, until this was later confirmed in Australia. Much of the world was introduced to the platypus in 1939 when National Geographic Society published an article on the platypus and the efforts to study and raise it in captivity. This is a very difficult task, and only a few young have been successfully raised since — notably at Healesville Sanctuary in Victoria (Australia). Seeing a platypus in the wild is more a matter of luck and of patience than of difficulty. They tend to dislike populated areas, spend almost all their time underground or under water, and are primarily nocturnal. However, they are not especially uncommon, and in suitable areas most keen fisherman or birdwatchers see a platypus feeding quietly along a riverbank every year or two. The platypus was hunted for its fur, but now does not appear to be in immediate danger of extinction. It is variously classified as ''secure but faces future threat'' or ''common but vulnerable'', mainly because the species is sensitive to water pollution. == The platypus in mammalian evolution == The platypus and other monotremes were very poorly understood for many years, and to this day some of the 19th century urban legend that grew up around them endure, for example, that the monotremes are "inferior" or quasi-reptilian, and that they are the distant ancestor of the "superior" placental mammals. It is now known that modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the marsupial and placental groups. The oldest fossils of monotremes (Teinolophos and Steropodon) are closely related to the modern platypus. A fossil relative of the platypus has been found in Argentina, indicating that monotremes may have reached South America from Australia, while the two continents were joined via Antarctica. In summary, the platypus is one of the closest relatives of ancestral mammals, but not itself a link in the chain of mammalian evolution. It is a branch quite separate from any other known one. Some people think that the platypus is more closely related to marsupials than it is to the spiny anteaters (Tachyglossidae). == Sex chromosomes == In 2004 researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared to two (XY) found in most other mammals. The chromosome system features characteristics found in mammals, but also those found in the WZ system of birds. This news has further pronounced the individuality of platypuses amongst the animal kingdom, and a target for further research into evolutionary links between mammals, birds and reptiles. ==Captive breeding== The platypus has proven itself extremely difficult to breed in captivity: Only four successful breeding occasions have been recorded. The leading person in these efforts was David Fleay who established a platypussary — a simulated stream in a tank — at the Healesville Sanctuary in Victoria (Australia) and had a successful breeding in 1943. Healesville repeated its successes in 1998 and in 2000 with a similar stream tank. Taronga Zoo in Sydney had success in 2003 with twins being bred. [http://www.abc.net.au/catalyst/stories/s988946.htm] (In 1972, David Fleay also found a dead baby about 50 days old, presumably bred, at his wildlife park at Burleigh Heads, Queensland on the Gold Coast, Queensland, Queensland. [http://www.epa.qld.gov.au/nature_conservation/wildlife/david_fleay_wildlife_park/50_years_wild/david_fleays_achievements/]) ==Name== The scientific name ''Ornithorhynchus'' is derived from ''ορνιθορυνχος'' (ornithorhynkhos), which literally means "bird nose" in Greek language, and ''anatinus'' means "duck". The common name is derived from the Greek words ''platus'' (flat) and ''pous'' (foot), meaning "flat foot" and was originally given to it as a Linnaean taxonomy genus name, but it was discovered to already belong to the wood-boring ambrosia beetle (genus ''Platypus''). The correct plural of platypus is ''platypuses'' (or sometimes ''platypus'') and not ''platypi'', as is sometimes heard. Australian Aborigines call the platypus by many names including mallangong, boondaburra, and tambreet. Early Britain settlers called it by many names as well, such as watermole, duckbill, and duckmole. The name platypus is often prefixed with the adjective "duck-billed" to form duck-billed platypus, despite there being only one species of platypus. == See also == * Australian fauna * Australian fauna#Mammals * Mammal * Monotreme == References and links == * Burrell, H. The Platypus. Adelaide: Rigby, 1974. * Griffiths, Mervyn. The Biology of the Monotremes. Academic Press, 1978. * Strahan, R. The Mammals of Australia. New South Wales: Reed Books, 1995. * [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v432/n7019/abs/nature03021_fs.html Nature abstract on sex chromosome discovery] * [http://www.totalretail.com/platypus Australian Platypus Conservancy Fact File] * [http://www.pbs.org/kratts/world/aust/plat/ PBS.org] * [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open Tasmanian Department of Primary Industries, Water, and Environment] * Augee, Michael L. Platypus. World Book Encyclopedia. 2001 ed. * Michael Hutch, Melissa C. McDade, eds. Grzimek's Animal Life Encyclopedia; Volume 12.'' ---- Detroit: Gale, 2004 Platypus was also the name of a progressive metal supergroup (bands) side-project featuring John Myung (of Dream Theater), Derek Sherinian (former Dream Theater member), Ty Tabor (of King's X), and Rod Morgenstein. Australian animals Monotremes fa:نوکاردکی ms:Platypus simple:Platypus
---- Shouldn't we have just the smaller picture here with a ''link'' to the larger one? Yes, but it takes more than 10 seconds to do it. I was in the middle of doing that when I got an "edit conflict". Battle of the dueling keyboards! :-) --User:Alan Millar :Sorry about that, that was probably me. But it was vitally important that I link :1800s and :1939 right then and there! :) -user:Bryan Derksen :Sorry. I just figured it out looking at it, and so had to try it to see if I was right. :-) --KQ --- Hmmm. Maybe I should go out to the Healsville Sanctuary and try to get a better photo. That drawing is very misleading. In fact, most 19th and early-20th centuary drawings of Australian wildlife are pretty inaccurate (and make it look uglier than it is). ---- The picture is better than none, perhaps. I like the idea of having the text first and then the picture. --User:LMS :Without dissing the considerable efforts of the person to track down a copyright-free illustration of a platypus, it really is *very* misleading. By all means keep it, but a better picture would be kinda nice. --User:Robert Merkel ---- I think the platypus has a poisonous claw - is that true? There's nothing in the article about it. User:207.189.98.44 20:12, 20 Feb 2004 (UTC) ---- In the article, it says that the platypus is listed as vulnerable, but on the right bar, it says that the platypus is secure. Are these referring to different things, or is one not correct? User:Bamos 17:13, 4 Apr 2004 (UTC) "The platypus conservation status, as listed on the endangered species list by the Australia and New Zealand Environmental Conservation Council, is 'secure but faces future threat'. Most information sources list the platypus as 'common but vulnerable'." from [http://www.earlham.edu/~whistem/platypusindex.htm earlham.edu]. So it is "Secure and facing future threat" and "common but vulnerable"... I guess this means that it is common now but the whole species is vulnerable to certain changes. I'll try to reword main article accordingly. --User:Mat-C 19:05, 4 Apr 2004 (UTC) ---- The statement on the platypus being the only mammal to have electroreception is false. All monotremes (the other being the Echnida) have electroreception. However, it ''is'' much more pronounced in the platypus. (Reference: ''Electroreception in monotremes'' J Exp Biol, 202 (10), 1447-1454 May 1999) ---- Why on the Platypus page does it mention that they look like beavers? I noticed on the beaver page it doesn't say they look like playtpusses. It seems a blantant North Hemisphere bias to me. Saying they look like beavers adds nothing to article, but I feel uncomfortable removing information from an article myself (being a newbie) ---- True or false: Approximately half of all American dictionaries accept "Platypi". User:66.32.148.182 01:15, 20 May 2004 (UTC) All I know is, ''Platypi'' is the logical Latin plural. American dictionaries usually prefer the logical English plural, like ''bureaus'' rather than the proper plural ''bureaux''. :But ''platypus'' is from Greek, not Latin! The Greek plural would be ''platypodes''. User:Gdr 14:29, 2004 Jul 26 (UTC) :: ''Platypodes'' is not a valid plural construction in English. Platypi is plain wrong, for the reasons given above. Scientists cannot seem to agree on whether to use ''platypuses'' (Tom Grant et al.) or ''platypus'' (Melody Serena et al.). Personally, I prefer the former, simply because it is less ambiguous. ---- This is from an editor who made some changes. I have altered some passages slightly to make them flow more smoothly. Also, I've inserted links (tribosphenic molar). A reorganisation of the sections (adding anatomy and behaviour headings). The formatting has been made universal: all family, species, genus, etc. names are made in italics, with no bold. Hopefully, this will work to the benefit of the article.--User:66.220.117.134 06:39, 27 May 2004 (UTC) ---- I haven't the time to make well-written and well-referenced changes to the page now, but still feel that I need to make a couple of comments... The statement that the metabolic rate of the platypus is low is plain wrong; the animal is known to eat copious amounts of food, around 20 percent of its body weight per day. (Reference: ''The Platypus - A Unique Mammal'' by Tom Grant, UNSW Press, 1995). The book by Tom Grant is undoubtedly one of the most trusted souces of reliable information about the platypus, and it is a shame it is not mentioned in the reference section. Furthermore, the platypus is not strictly nocturnal, but is commonly biurnal (active during mornings and evenings), or even active during daytime. This varies greatly among populations and individual animals. The section which mentions water pollution as a threat to the platypus could be expanded considerably. Interaction with foxes and humans is probably the most important local threat to the species. The Australian Platypus Conservancy is a good source of information on these topics. The genetics of this remarkable species is a fascinating topic, and should be discussed more in depth. For example, Tasmanian platypuses have been found to differ genetically from mainland platypuses by as much as 5 percent (humans and chimpanzees also differ by about 5 percent). This difference may partly explain the susceptibility of Tasmanian platypuses - but not mainland ones - to the fungal infection ulcerative mycosis, caused by ''Mucor amphibiorum'', which is a common cause of platypus mortality in Tasmania. Regarding pictures, there should definitly be some accurate photographs on the platypus page. The 19th century drawing is not accurate or sufficient. I might have some pictures somewhere that I took myself a few years ago; e-mail me if you feel like putting them up on the web. -- Peter Modin (peter_modin AT hotmail.com) == New information == http://www.abc.net.au/news/newsitems/200410/s1226827.htm This article references new information about platypus sex. Apparantly they have 5 chromosomes to determine it. On another note, this is the first I've contributed anything to wikipedia, so I didn't make the direct changes myself. My, what a wonderful article!!! I used the info from the platypus to do a bio report and got an A! Wikipedia really does work! ---Christina ==Lack of references== Hi this article no longer meets the Wikipedia:What is a featured article for a featured article because it does not Wikipedia:Cite sources. Please help fix this so that all featured articles can meet the same standards. Best would be the most trusted resources in the field being added, some print resources especially, but also online references are better than none. Those sources would likely help with good material to further improve the article anyway. - User:Taxman 23:00, Oct 26, 2004 (UTC) :I have added three printed sources and three websites. Hope it helps.
One of the websites, [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open] would be very useful for expanding the article. Also, according to the disclaimer and copyright information, Wikipedia may be able to use some of the images on this site, as the only good image we have is probably a copyright infringement ('Apart from any use permitted by the [Australian Copyright Act 1968], the State of Tasmania grants users of this site a licence (within the meaning of the Act) to download, print and otherwise reproduce the information for non-commercial purposes only.'). User:IngoolemoUser_talk:IngoolemoUser:IngoolemoUser_talk:Ingoolemo 03:10, 2004 Nov 11 (UTC) hi i love you == On the plural once again == During the discussion above, we have come to several conclusions regarding the plural of ''platypus'': * The logical Latin plural is ''platypi'' ** Since platypus isn't Latin, ''platypi'' is not a real world * The Greek plural of ''platypus'' is ''πλατυπωδεσ'' (''platypodes'') * Platypodes is an invalid plural in English, since there is no precedent for Greek plurals * Scientists are divided between ** ''platypuses'' ** and ''platypus'' * At least two Wikipedia users (me and the anon who posted the response) prefer the former, since it is less ambiguous. In my opinion, this issue of plural needs to be addressed somewhere in the article. If no one objects, I'm going to add it somewhere in the front, like at the end of the intro section. Also, if the proper Greek spelling of ''platypodes'' could be confirmed, that would be great. User:Ingoolemo User_talk:Ingoolemo Donations for victims of the 2004 Indian Ocean earthquake 23:06, 2005 Feb 9 (UTC) :My dictionaries give the following for the plural: * platypuses (Collins, The American Heritage® Dictionary of the English Language) * platypuses and (surprisingly) platypi (Webster's New Collegiate Dictionary, Encarta World Dictionary) * no mention of a plural (The New Shorter Oxford English Dictionary; Longman Modern English Dictionary, Cambridge Advanced Learner's Dictionary) User:JoJan 06:55, 10 Feb 2005 (UTC)
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:''This article is about the mammal. For the genus see ambrosia beetle.''
The platypus (''Ornithorhynchus anatinus'') is a small, semi-aquatic mammal endemic (ecology) to the eastern part of Australia, and one of the four extant monotremes, the only mammals that lay egg (biology) instead of giving birth to live young (the other three are echidnas). It is the sole representative of its family (biology) (''Ornithorhynchidae'') and genus (''Ornithorhynchus''), though a number of Monotreme#Fossil Monotremes have been found, some of them also in the ''Ornithorhynchus'' genus. The platypus is considered one of the strangest specimens of the animal kingdom: a venomous, egg-laying, duck-billed mammal. == Physiology and anatomy == The platypus' metabolic rate is remarkably low compared to other mammals, with a body temperature averaging 32°Celsius (90°Fahrenheit) rather than the 38°C (100.4°F) typical of placentalia. The extent to which this is a characteristic of monotremes, as opposed to an adaptation on the part of the small number of surviving species to harsh environmental conditions, is uncertain. The body and the broad, flat tail of the platypus are covered with brown fur. It has webbed feet and a large, rubbery snout that are more reminiscent of a duck's features than those of any known mammal. Weight varies considerably between less than a kilogram (two Pound#Pound (avoirdupois) or international pounds) and over two kilograms (just under four and one half pounds); with body length ranging from 30 to 40 centimetre (nearly 1Foot (unit of length) to 1'3inch), and tail length from 10 to 15 cm (4" to 6") for males and 8 to 13 cm (3" to 5") for females. Males are around one-third larger than females. There is substantial variation in average size from one region to another, though oddly this pattern does not seem to follow any particular climate rule. Modern platypus young have ''tribosphenic molar'' (three-cusped) molar (tooth)s, which are one of the hallmarks of mammals; adults are toothless. The platypus jaw is constructed somewhat differently from that of other mammals, and the jaw opening muscle is different. As in all true mammals, the tiny bones that conduct sound to the inner ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other pre-mammalian synapsids. However, the external opening of the ear still lies at the base of the jaw. The platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals. It also has a reptile-like gait, with legs that are on the sides of rather than underneath the body. The male platypus has venomous ankle spurs, used in vicious territorial battles and fights over mates. The poison is not lethal to humans but produces excruciating pain and inflammation that may last for several months. The venom can be lethal to dogs and smaller domestic animals. The male platypus reproductive structure is much like that of other mammals. One exception is that their testicles are inside their body, near their kidneys. The female reproductive system, on the other hand, differs from other placental mammals. Their paired ovaries resemble those of birds and reptiles. Although the platypus has two separate ovaries, only the left one is functional. The other is primitive and underdeveloped, and does not produce eggs. == Reproduction == ===Courtship=== The platypus’ behavior before mating is complex but relatively undocumented. The breeding season is in the late winter to early spring, which in Australia is August to November. A male will mate with any number of females during this time, for the platypus does not form life-long mates. Few platypuses have been seen mating, but courtship has been recorded to involve the male chasing and circling the female and biting her tail. Platypus are usually solitary animals, but during courtship, bodily contact between the pair is increased. During mating, the male curls his tail beneath the female, and lays his chest on the female’s back. There have been about five different recorded courtship methods. The first involves the male resting on the water, and the female swimming over to him and resting her muzzle on his. The second included the female swimming to the male and rubbing his side. The third recorded the female swimming beneath the male upside down, while rubbing his abdomen. The fourth documented the female swimming underneath the male and surfacing behind him. Finally, the fifth recorded instance included the female and male circling one another in tight circles. ===Development/Gestation=== Platypuses lay small, leathery eggs similar to those of reptiles, which are slightly rounder than bird eggs. Females usually lay two eggs at a time, but sometimes they lay one egg or three, which are about 1and 1/7 cm in diameter. The incubation period is separated into three parts . In the first, the embryo has no functional organs and relies on the yolk sac for respiration. During the second, the fingers and toes appear, and in the last, the egg tooth appears. ===Parental Investment=== Outside the mating season, platypuses live in simple burrows in the ground. After mating, though, the female constructs a deeper, more elaborate burrow, while the male takes no part in caring for its young, and retreats to its yearlong burrow. The new nesting burrow that females dig may be as long as 85 feet. The burrow's entrance is about one foot above the water. The female softens the ground in the burrow with dead, folded, wet leaves. After the eggs hatch, the mother only leaves the burrow for short periods of time to feed and wet her fur. When the mother leaves her young, she plugs the entrance with soil to protect her offspring. After laying her eggs, the female curls around them. The newly hatched platypuses are vulnerable, blind, and nude, and are fed by the mother's milk. Although she does not have nipples, the milk is released through pores in her abdomen. There are grooves on her abdomen that form pools of milk, allowing the young platypuses to lap up the milk. The offspring are suckled for three to four months after they have hatched. They leave the burrow when they are seventeen weeks old. == Platypus venom == Venom is produced in the crural glands of the male during the breeding season and is aggressively inflicted through a calcaneous spur on each hind limb. Because the venom appears to have a different function from venoms produced by non-mammalian species, it may contain peptides or molecules whose principal effects are non-life threatening but nevertheless may seriously impair the victim. That this could be the case is evident from the symptoms of platypus envenomation. In humans the most remarkable symptom is immediate and excruciating pain. Edema rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from case study and anecdotal evidence indicates that the pain develops into a long-lasting hyperalgesia that persists for days or even months. == Ecology and behaviour == The platypus is nocturnal and semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula. Inland, its distribution is not well known: it is extinct in South Australia (bar an introduced population on Kangaroo Island) and is no longer found in the main part of the Murray-Darling Basin, probably because of the declining water quality brought about by extensive land clearing and irrigation schemes. Along the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower Maribyrnong_River, for example). The platypus is an excellent swimmer and spends much of its time in the water. When swimming they are distinguished from other Australian mammals by the absence of visible ears. It keeps its eyes tightly shut when swimming, relying completely on its other senses. All four feet of the platypus are webbed. When it swims, it propels itself by paddling with the front two feet. The tail and hind feet assist in steering but not propulsion. The platypus is a carnivore. It feeds on worms and larva, freshwater shrimps, and yabbies (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. Its bill is very sensitive, allowing it to hunt its food without using sight. It is one of the few mammals known to have a sense of Electroception: it locates its prey in part by detecting their body electricity. Its electroception is the most sensitive of any mammal. This is discussed in more detail below. When not in the water, the platypus retires to a short, straight burrow of oval cross-section, nearly always in the riverbank not far above water level, and often camouflage under a protective tangle of roots. For breeding, the female digs much larger and more elaborate burrows, up to 20 metre long and blocked with plugs at intervals. She fills the nest at the end of the tunnel with reeds for bedding material. As a monotreme, the platypus does not give birth to live young but instead lays eggs in its burrow. During the mating season, the female builds a nest of leaves and grass at the end of her burrow, located in the banks of streams. Before laying her eggs, she blocks the entrances to the burrow with dirt. Female platypuses lay one to three eggs at a time. The eggs are retained in the body for some time before they are laid and cared for actively by the parent. When the eggs hatch after an incubate period of roughly ten days, the small hairless babies cling to the mother. Like other mammals, the mother produces milk for the young. The platypus does not have nipples, but excretes the milk through pores in her skin. The young suckle milk off the mother's belly while she lies on her back. == Electrolocation in the platypus == In the platypus, receptor (biochemistry) are located in rostro-caudal rows in the skin of the bill, while mechanoreceptors are uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals. The platypus feeds by digging in the bottom of streams with the bill. In this situation, the electroreceptors could also be used to distinguish animate and inanimate objects in this situation (where the mechanoreceptors would be continuously stimulated). Much of this is speculation, and there is still much to be learned about electroreception in the platypus and its fellow monotreme, the echidna. == Field biology of the platypus == The field biology of the platypus was first studied by a number of expatriate biologists who visited the Australian colonies to collect specimens in the 1800s. Their work was followed in the early to mid-1900s by a group of resident natural historians and later by an increasing number of academic biologists. All of these workers contributed significantly to the current understanding of the field biology of this unique Australian species. The platypus occupies much the same general distribution as it did prior to European occupation of Australia, except for its loss from the state of South Australia. However, local changes and fragmentation of distribution due to human modification of its habitat are documented. The species currently inhabits eastern Australia from around Cooktown in the north to Tasmania in the south. Although not found in the west-flowing rivers of northern Queensland, it inhabits the upper reaches of rivers flowing to the west and north of the dividing ranges in the south of the state and in New South Wales and Victoria. Its current and historical abundance, however, is less well known and it has probably declined in numbers, although still being considered as common over most of its current range. The species was extensively hunted for its fur until around the turn of the 20th century. The platypus is mostly nocturnal in its foraging activities, being predominantly an opportunistic carnivore of benthic invertebrates. The species is endothermic, maintaining its low body temperature (32°C), even while foraging for hours in water below 5°C. Its major habitat requirements include both riverine and riparian features which maintain a supply of benthic prey species and consolidated banks into which resting and nesting burrows can be excavated. The species exhibits a single breeding season, with mating occurring in late Winter or Spring (season) and young first emerging into the water after 3-4 months of nurture by the lactating females in the nesting burrows. Natural history observations, mark and recapture studies and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a polygyny mating system. Recent field studies have largely confirmed and extended the work of the early biologists and natural historians. == Scientific history == When the platypus was first discovered by Europeans in the late 1700s, a pelt was sent back to Britain for examination by the scientific community. The British scientists were at first convinced that the seemingly odd collection of physical attributes must be a hoax, produced by some Asian taxidermy. It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Scientists were also divided over whether the female platypus laid eggs, until this was later confirmed in Australia. Much of the world was introduced to the platypus in 1939 when National Geographic Society published an article on the platypus and the efforts to study and raise it in captivity. This is a very difficult task, and only a few young have been successfully raised since — notably at Healesville Sanctuary in Victoria (Australia). Seeing a platypus in the wild is more a matter of luck and of patience than of difficulty. They tend to dislike populated areas, spend almost all their time underground or under water, and are primarily nocturnal. However, they are not especially uncommon, and in suitable areas most keen fisherman or birdwatchers see a platypus feeding quietly along a riverbank every year or two. The platypus was hunted for its fur, but now does not appear to be in immediate danger of extinction. It is variously classified as ''secure but faces future threat'' or ''common but vulnerable'', mainly because the species is sensitive to water pollution. == The platypus in mammalian evolution == The platypus and other monotremes were very poorly understood for many years, and to this day some of the 19th century urban legend that grew up around them endure, for example, that the monotremes are "inferior" or quasi-reptilian, and that they are the distant ancestor of the "superior" placental mammals. It is now known that modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the marsupial and placental groups. The oldest fossils of monotremes (Teinolophos and Steropodon) are closely related to the modern platypus. A fossil relative of the platypus has been found in Argentina, indicating that monotremes may have reached South America from Australia, while the two continents were joined via Antarctica. In summary, the platypus is one of the closest relatives of ancestral mammals, but not itself a link in the chain of mammalian evolution. It is a branch quite separate from any other known one. Some people think that the platypus is more closely related to marsupials than it is to the spiny anteaters (Tachyglossidae). == Sex chromosomes == In 2004 researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared to two (XY) found in most other mammals. The chromosome system features characteristics found in mammals, but also those found in the WZ system of birds. This news has further pronounced the individuality of platypuses amongst the animal kingdom, and a target for further research into evolutionary links between mammals, birds and reptiles. ==Captive breeding== The platypus has proven itself extremely difficult to breed in captivity: Only four successful breeding occasions have been recorded. The leading person in these efforts was David Fleay who established a platypussary — a simulated stream in a tank — at the Healesville Sanctuary in Victoria (Australia) and had a successful breeding in 1943. Healesville repeated its successes in 1998 and in 2000 with a similar stream tank. Taronga Zoo in Sydney had success in 2003 with twins being bred. [http://www.abc.net.au/catalyst/stories/s988946.htm] (In 1972, David Fleay also found a dead baby about 50 days old, presumably bred, at his wildlife park at Burleigh Heads, Queensland on the Gold Coast, Queensland, Queensland. [http://www.epa.qld.gov.au/nature_conservation/wildlife/david_fleay_wildlife_park/50_years_wild/david_fleays_achievements/]) ==Name== The scientific name ''Ornithorhynchus'' is derived from ''ορνιθορυνχος'' (ornithorhynkhos), which literally means "bird nose" in Greek language, and ''anatinus'' means "duck". The common name is derived from the Greek words ''platus'' (flat) and ''pous'' (foot), meaning "flat foot" and was originally given to it as a Linnaean taxonomy genus name, but it was discovered to already belong to the wood-boring ambrosia beetle (genus ''Platypus''). The correct plural of platypus is ''platypuses'' (or sometimes ''platypus'') and not ''platypi'', as is sometimes heard. Australian Aborigines call the platypus by many names including mallangong, boondaburra, and tambreet. Early Britain settlers called it by many names as well, such as watermole, duckbill, and duckmole. The name platypus is often prefixed with the adjective "duck-billed" to form duck-billed platypus, despite there being only one species of platypus. == See also == * Australian fauna * Australian fauna#Mammals * Mammal * Monotreme == References and links == * Burrell, H. The Platypus. Adelaide: Rigby, 1974. * Griffiths, Mervyn. The Biology of the Monotremes. Academic Press, 1978. * Strahan, R. The Mammals of Australia. New South Wales: Reed Books, 1995. * [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v432/n7019/abs/nature03021_fs.html Nature abstract on sex chromosome discovery] * [http://www.totalretail.com/platypus Australian Platypus Conservancy Fact File] * [http://www.pbs.org/kratts/world/aust/plat/ PBS.org] * [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open Tasmanian Department of Primary Industries, Water, and Environment] * Augee, Michael L. Platypus. World Book Encyclopedia. 2001 ed. * Michael Hutch, Melissa C. McDade, eds. Grzimek's Animal Life Encyclopedia; Volume 12.'' ---- Detroit: Gale, 2004 Platypus was also the name of a progressive metal supergroup (bands) side-project featuring John Myung (of Dream Theater), Derek Sherinian (former Dream Theater member), Ty Tabor (of King's X), and Rod Morgenstein. Australian animals Monotremes fa:نوکاردکی ms:Platypus simple:Platypus
Platypus
---- Shouldn't we have just the smaller picture here with a ''link'' to the larger one? Yes, but it takes more than 10 seconds to do it. I was in the middle of doing that when I got an "edit conflict". Battle of the dueling keyboards! :-) --User:Alan Millar :Sorry about that, that was probably me. But it was vitally important that I link :1800s and :1939 right then and there! :) -user:Bryan Derksen :Sorry. I just figured it out looking at it, and so had to try it to see if I was right. :-) --KQ --- Hmmm. Maybe I should go out to the Healsville Sanctuary and try to get a better photo. That drawing is very misleading. In fact, most 19th and early-20th centuary drawings of Australian wildlife are pretty inaccurate (and make it look uglier than it is). ---- The picture is better than none, perhaps. I like the idea of having the text first and then the picture. --User:LMS :Without dissing the considerable efforts of the person to track down a copyright-free illustration of a platypus, it really is *very* misleading. By all means keep it, but a better picture would be kinda nice. --User:Robert Merkel ---- I think the platypus has a poisonous claw - is that true? There's nothing in the article about it. User:207.189.98.44 20:12, 20 Feb 2004 (UTC) ---- In the article, it says that the platypus is listed as vulnerable, but on the right bar, it says that the platypus is secure. Are these referring to different things, or is one not correct? User:Bamos 17:13, 4 Apr 2004 (UTC) "The platypus conservation status, as listed on the endangered species list by the Australia and New Zealand Environmental Conservation Council, is 'secure but faces future threat'. Most information sources list the platypus as 'common but vulnerable'." from [http://www.earlham.edu/~whistem/platypusindex.htm earlham.edu]. So it is "Secure and facing future threat" and "common but vulnerable"... I guess this means that it is common now but the whole species is vulnerable to certain changes. I'll try to reword main article accordingly. --User:Mat-C 19:05, 4 Apr 2004 (UTC) ---- The statement on the platypus being the only mammal to have electroreception is false. All monotremes (the other being the Echnida) have electroreception. However, it ''is'' much more pronounced in the platypus. (Reference: ''Electroreception in monotremes'' J Exp Biol, 202 (10), 1447-1454 May 1999) ---- Why on the Platypus page does it mention that they look like beavers? I noticed on the beaver page it doesn't say they look like playtpusses. It seems a blantant North Hemisphere bias to me. Saying they look like beavers adds nothing to article, but I feel uncomfortable removing information from an article myself (being a newbie) ---- True or false: Approximately half of all American dictionaries accept "Platypi". User:66.32.148.182 01:15, 20 May 2004 (UTC) All I know is, ''Platypi'' is the logical Latin plural. American dictionaries usually prefer the logical English plural, like ''bureaus'' rather than the proper plural ''bureaux''. :But ''platypus'' is from Greek, not Latin! The Greek plural would be ''platypodes''. User:Gdr 14:29, 2004 Jul 26 (UTC) :: ''Platypodes'' is not a valid plural construction in English. Platypi is plain wrong, for the reasons given above. Scientists cannot seem to agree on whether to use ''platypuses'' (Tom Grant et al.) or ''platypus'' (Melody Serena et al.). Personally, I prefer the former, simply because it is less ambiguous. ---- This is from an editor who made some changes. I have altered some passages slightly to make them flow more smoothly. Also, I've inserted links (tribosphenic molar). A reorganisation of the sections (adding anatomy and behaviour headings). The formatting has been made universal: all family, species, genus, etc. names are made in italics, with no bold. Hopefully, this will work to the benefit of the article.--User:66.220.117.134 06:39, 27 May 2004 (UTC) ---- I haven't the time to make well-written and well-referenced changes to the page now, but still feel that I need to make a couple of comments... The statement that the metabolic rate of the platypus is low is plain wrong; the animal is known to eat copious amounts of food, around 20 percent of its body weight per day. (Reference: ''The Platypus - A Unique Mammal'' by Tom Grant, UNSW Press, 1995). The book by Tom Grant is undoubtedly one of the most trusted souces of reliable information about the platypus, and it is a shame it is not mentioned in the reference section. Furthermore, the platypus is not strictly nocturnal, but is commonly biurnal (active during mornings and evenings), or even active during daytime. This varies greatly among populations and individual animals. The section which mentions water pollution as a threat to the platypus could be expanded considerably. Interaction with foxes and humans is probably the most important local threat to the species. The Australian Platypus Conservancy is a good source of information on these topics. The genetics of this remarkable species is a fascinating topic, and should be discussed more in depth. For example, Tasmanian platypuses have been found to differ genetically from mainland platypuses by as much as 5 percent (humans and chimpanzees also differ by about 5 percent). This difference may partly explain the susceptibility of Tasmanian platypuses - but not mainland ones - to the fungal infection ulcerative mycosis, caused by ''Mucor amphibiorum'', which is a common cause of platypus mortality in Tasmania. Regarding pictures, there should definitly be some accurate photographs on the platypus page. The 19th century drawing is not accurate or sufficient. I might have some pictures somewhere that I took myself a few years ago; e-mail me if you feel like putting them up on the web. -- Peter Modin (peter_modin AT hotmail.com) == New information == http://www.abc.net.au/news/newsitems/200410/s1226827.htm This article references new information about platypus sex. Apparantly they have 5 chromosomes to determine it. On another note, this is the first I've contributed anything to wikipedia, so I didn't make the direct changes myself. My, what a wonderful article!!! I used the info from the platypus to do a bio report and got an A! Wikipedia really does work! ---Christina ==Lack of references== Hi this article no longer meets the Wikipedia:What is a featured article for a featured article because it does not Wikipedia:Cite sources. Please help fix this so that all featured articles can meet the same standards. Best would be the most trusted resources in the field being added, some print resources especially, but also online references are better than none. Those sources would likely help with good material to further improve the article anyway. - User:Taxman 23:00, Oct 26, 2004 (UTC) :I have added three printed sources and three websites. Hope it helps.
One of the websites, [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open] would be very useful for expanding the article. Also, according to the disclaimer and copyright information, Wikipedia may be able to use some of the images on this site, as the only good image we have is probably a copyright infringement ('Apart from any use permitted by the [Australian Copyright Act 1968], the State of Tasmania grants users of this site a licence (within the meaning of the Act) to download, print and otherwise reproduce the information for non-commercial purposes only.'). User:IngoolemoUser_talk:IngoolemoUser:IngoolemoUser_talk:Ingoolemo 03:10, 2004 Nov 11 (UTC) hi i love you == On the plural once again == During the discussion above, we have come to several conclusions regarding the plural of ''platypus'': * The logical Latin plural is ''platypi'' ** Since platypus isn't Latin, ''platypi'' is not a real world * The Greek plural of ''platypus'' is ''πλατυπωδεσ'' (''platypodes'') * Platypodes is an invalid plural in English, since there is no precedent for Greek plurals * Scientists are divided between ** ''platypuses'' ** and ''platypus'' * At least two Wikipedia users (me and the anon who posted the response) prefer the former, since it is less ambiguous. In my opinion, this issue of plural needs to be addressed somewhere in the article. If no one objects, I'm going to add it somewhere in the front, like at the end of the intro section. Also, if the proper Greek spelling of ''platypodes'' could be confirmed, that would be great. User:Ingoolemo User_talk:Ingoolemo Donations for victims of the 2004 Indian Ocean earthquake 23:06, 2005 Feb 9 (UTC) :My dictionaries give the following for the plural: * platypuses (Collins, The American Heritage® Dictionary of the English Language) * platypuses and (surprisingly) platypi (Webster's New Collegiate Dictionary, Encarta World Dictionary) * no mention of a plural (The New Shorter Oxford English Dictionary; Longman Modern English Dictionary, Cambridge Advanced Learner's Dictionary) User:JoJan 06:55, 10 Feb 2005 (UTC)
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