Editing Emu (section)

== Description ==
The emu is the second tallest bird in the world, only being exceeded in height by the [[ostrich]];<ref>{{cite book|author1=Gillespie, James|author2=Flanders, Frank |title=Modern Livestock & Poultry Production|url=https://books.google.com/books?id=7Z9o_vGPP4cC&pg=PA908 |year=2009 |publisher=Cengage Learning |isbn=978-1-4283-1808-3 |page=908}}</ref> the largest individuals can reach up to {{convert|150|to|190|cm|in|abbr=on}} in height. Measured from the bill to the tail, emus range in length from {{convert|139|to|164|cm|in|abbr=on}}, with males averaging {{convert|148.5|cm|in|abbr=on}} and females averaging {{convert|156.8|cm|in|abbr=on}}.<ref name="S. Davies">{{cite book|title=Ratites and Tinamous|author=Stephen Davies |year=2002 |publisher=Oxford University Press |isbn=978-0-19-854996-3}}</ref> Emus are the fourth or fifth heaviest living bird after the two species of ostrich and two larger species of [[cassowary]], weighing slightly more on average than an [[emperor penguin]]. Adult emus weigh between {{convert|18|and|60|kg|lb|abbr=on}}, with an average of {{convert|31.5|and|37|kg|lb|abbr=on}} in males and females, respectively.<ref name="S. Davies" /> Females are usually slightly larger than males and are substantially wider across the rump.<ref name=e6 />

{{multiple image|perrow=2/2|total_width=360|caption_align=center
| align = right
| image_style = border:none;
| image1= Dromaius novaehollandiae -zoo -two feet.jpg
| image2= Dromaius novaehollandiae (head) Battersea Park Children's Zoo.jpg
| image3= Emu size.png
| image4= Emu-wild.jpg
| footer = {{font|size=100%|font=Sans-serif|text=Top left: Emus have three toes on each [[Bird feet and legs|foot]] in a [[Dactyly#In birds|tridactyl]] arrangement, which is an adaptation for running and is seen in other birds, such as [[bustard]]s and [[quail]]s. The [[ostrich]] has two toes on each foot. Top right:  Emu head and upper neck. Bottom left: Size comparison between a human, mainland emu (centre), and extinct King Island subspecies (right). Bottom right: Adult in South Eastern [[Australia]].}} 
}}

Although flightless, emus have [[vestigial]] wings, the [[Wing chord (biology)|wing chord]] measuring around {{convert|20|cm|in|0|abbr=on}}, and each wing having a small claw at the tip.<ref name="S. Davies" /> Emus flap their wings when running, perhaps as a means of stabilising themselves when moving fast.<ref name=e5 /> They have long necks and legs,<ref name=e6>Eastman, p. 6.</ref> and can run at speeds of {{convert|48|km/h|mph|abbr=on}} due to their highly specialised [[Pelvis#Other animals|pelvic]] limb musculature.<ref name="S. Davies" /> Their [[Bird feet and legs|feet]] have only three toes and a similarly reduced number of bones and associated foot muscles; emus are unique among birds in that their [[gastrocnemius muscle]]s in the back of the lower legs have four bellies instead of the usual three. The pelvic limb muscles of emus contribute a similar proportion of the total body mass as do the flight muscles of flying birds.<ref>{{cite journal |doi=10.1002/(SICI)1097-4687(199810)238:1<23::AID-JMOR2>3.0.CO;2-O |author1=Patak, A.E. |author2=Baldwin, J. |year=1998 |title=Pelvic limb musculature in the emu ''Dromaius novaehollandiae'' (Aves : Struthioniformes: Dromaiidae): Adaptations to high-speed running |journal=Journal of Morphology |volume=238 |issue=1 |pages=23–37 |pmid=9768501|s2cid=44693723 }}</ref> When walking, the emu takes strides of about {{convert|100|cm|ft|abbr=on}}, but at full gallop, a stride can be as long as {{convert|275|cm|ft|0|abbr=on}}.<ref name=e9 /> Its legs are devoid of feathers and underneath its feet are thick, cushioned pads.<ref name=e9 /> Like the cassowary, the emu has sharp claws on its toes which are its major defensive attribute, and are used in combat to inflict wounds on opponents by kicking.<ref name=e7>Eastman, p. 7.</ref> The toe and claw total {{convert|15|cm|in|0|abbr=on}} in length.<ref name=e9>Eastman, p. 9.</ref> The bill is quite small, measuring {{convert|5.6|to|6.7|cm|in|abbr=on}}, and is soft, being adapted for grazing.<ref name="S. Davies" /> Emus have good eyesight and hearing, which allows them to detect threats at some distance.<ref>{{cite web |url=http://www.wildlifeextra.com/go/world/EMUS-vs-OSTRICHES%20.html#cr |title=Emus vs. Ostriches |publisher=Wildlife Extra |access-date=19 July 2015 |archive-url=https://web.archive.org/web/20150718231953/http://www.wildlifeextra.com/go/world/EMUS-vs-OSTRICHES%20.html#cr |archive-date=18 July 2015 |url-status=dead }}</ref>
[[File:Pale Emu Blues.jpg|thumb|177x177px|Detail of the skin  under its neck from a captive specimen]]
The neck of the emu is pale blue and shows through its sparse feathers.<ref name="S. Davies" /> They have grey-brown plumage of shaggy appearance;<ref name="AM" /> the shafts and the tips of the [[feather]]s are black. Solar radiation is absorbed by the tips, and the inner [[plumage]] insulates the skin.<ref>{{cite journal |doi=10.1016/0306-4565(94)00073-R |author1=Maloney, S.K. |author2=Dawson, T.J. |year=1995 |title=The heat load from solar radiation on a large, diurnally active bird, the emu (''Dromaius novaehollandiae'') |journal=Journal of Thermal Biology |volume=20 |pages=381–387 |issue=5|bibcode=1995JTBio..20..381M }}</ref> This prevents the birds from overheating, allowing them to be active during the heat of the day.<ref>Eastman, pp. 5–6.</ref> A unique feature of the emu feather is the double [[rachis]] emerging from a single shaft. Both of the rachis have the same length, and the texture is variable; the area near the skin is rather furry, but the more distant ends resemble grass.<ref name=e5 /> The sexes are similar in appearance,<ref name=e23>Eastman, p. 23.</ref> although the male's penis can become visible when he urinates and defecates.<ref name=Coddington>{{cite journal|doi=10.1071/ZO9950365 |journal=Australian Journal of Zoology |year=1995 |volume=43 |pages= 365–372|title=The mating system of free-living emus |author1=Coddington, Catherine L. |author2=Cockburn, Andrew |issue=4}}</ref> The plumage varies in colour due to environmental factors, giving the bird a natural [[camouflage]]. Feathers of emus in more arid areas with red soils have a rufous tint while birds residing in damp conditions are generally darker in hue.<ref name=e6 /> The juvenile plumage develops at about three months and is blackish finely barred with brown, with the head and neck being especially dark. The facial feathers gradually thin to expose the bluish skin. The adult plumage has developed by about fifteen months.<ref name=HBWA/>

The eyes of an emu are protected by [[nictitating membrane]]s. These are translucent, secondary eyelids that move horizontally from the inside edge of the eye to the outside edge. They function as visors to protect the eyes from the dust that is prevalent in windy arid regions.<ref name=e6 /> Emus have a [[trachea]]l pouch, which becomes more prominent during the mating season. At more than {{convert|30|cm|in|abbr=on}} in length, it is quite spacious; it has a thin wall, and an opening {{convert|8|cm|in|0}} long.<ref name=e6 />