Beak 198154 218215948 2008-06-09T17:58:44Z Revision17 73871 added pufferfish to the list of animals with 'beaks' {{alternateuses}} {| align=right |[[Image:Eagle beak sideview A.jpg|thumb|right|The bill of a scavenger—the [[vulture]].]] |- |[[Image:Anser cygnoides.jpg|thumb|right|The bill and knob of a [[domesticated goose|domesticated Chinese goose]], highly exaggerated by farm selection.]] |- |[[Image:Morus bassanus billing.jpg|thumb|right|[[Northern Gannet]]s <i>([[Northern Gannet|Morus bassanus]])</i> billing.]] |- |[[Image:bristol.zoo.greater.flamingo.arp.jpg|thumb|right|The bill of the Greater Flamingo, <i>[[Greater_Flamingo|Phoenicopterus roseus]].</i>]] |- |[[Image:Brown falcon1444.jpg|thumb|right|The beak of a Brown Falcon, <i>[[Falco berigora]].</i>]] |- |[[Image:Beak_of_an_African_Penguin.jpeg|thumb|right|The beak of an African Penguin, <i>[[Spheniscus demersus]].</i>]] |} The '''beak''', '''bill''' or '''rostrum''' is an external anatomical structure of [[birds]] which, in addition to eating, is used for [[Personal grooming#In animals|grooming]], manipulating objects, killing prey, probing for food, [[Courtship#Courtship in the animal kingdom|courtship]] and feeding their young. The term also refers to a similar mouthpart in some [[cephalopod]]s, [[cetacean]]s, [[Tetraodontidae|pufferfish]]es, [[turtle]]s, [[Anuran]] [[tadpole]]s and [[Sirenidae|siren]]s. [[Image:BirdBeaksA.svg|thumb|left|Comparison of different types of bird beaks, displaying the different shapes that are a result of different feeding adaptations. Bird heads are not shown to scale.]] ==Anatomy== <!-- This section is linked from [[Stegosaurus]] --> Beaks can vary significantly in size and shape from species to species. The beak is composed of an upper jaw called the [[maxilla]], and a lower jaw called the [[mandible]]. The jaw is made of bone, typically hollow or porous to conserve weight for flying. The outside surface of the beak is covered by a thin horny sheath of [[keratin]] called the '''rhamphotheca'''. Between the hard outer layer and the bone is a vascular layer containing [[blood vessel]]s and nerve endings. The rhamphotheca also includes the '''knob''' which is found above the beak of some swans, such as the [[Mute Swan]], and some [[domesticated goose|domesticated Chinese geese]] (''pictured''). The beak has two holes called '''[[nares]]''' ([[nostrils]]) which connect to the hollow inner beak and thence to the [[Lung#Avian_lungs|respiratory system]]. The nares are usually located directly above the beak. In some birds, they are located in a fleshy, often waxy structure at the base of the beak called the '''cere''' (from [[Latin]] ''cera''). [[Hawk]]s, [[parrot]]s, [[dove]]s, [[skua]]s and [[budgerigar]]s are among the birds that have ceres. Budgerigars are [[Sexual dimorphism|dimorphic]] in that the males' ceres turn bright blue upon maturity, while the females' ceres turn tan. The female budgies' ceres also appear wrinkled, to a greater extent during periods of fertility. Immature budgies have pale pinkish ceres which are smooth and shiny. On some birds, the tip of the beak is hard, dead tissue used for heavy-duty tasks such as cracking nuts or killing prey. On other birds, such as ducks, the tip of the bill is sensitive and contains nerves, for locating things by touch. The beak is worn down by use, so it grows continuously throughout the bird's life. Unlike jaws with teeth, beaks are not used for chewing. Birds swallow their food whole, which is broken up in the [[gizzard]]. Examples of birds with unusual beaks include the [[hummingbird]], the [[toucan]] and the [[spoonbill]]. In the [[mallard]], and perhaps in other [[duck]]s, there is no cere, and the nostrils are in the hard part of the beak, as a soft cere would be liable to injury when the duck dredges for food among submerged debris and stones. == Billing == During courtship, mated pairs of a variety of bird species touch and clasp each other's bills. This is called '''billing''', and appears to strengthen the [[pair bond]] (Terres, 1980). [[Gannet]]s raise their bills high and repeatedly clatter them (''pictured''); the male [[puffin]] nibbles at the female's beak; the male [[waxwing]] puts his bill in the female's mouth; and [[raven]]s hold each other's beaks in a prolonged "kiss". ==Terminology== The term '''decurved''' refers to a downward curving beak.<br> ==See also== * [[Bird anatomy]] ==References== *Gilbertson, Lance; ''Zoology Lab Manual''; McGraw Hill Companies, New York; ISBN 0-07-237716-X (fourth edition, 1999) *Terres, John. K. ''The Audubon Society Encyclopedia of North American Birds'', New York: Alfred A. Knopf, 1980. ISBN 0-394-46651-9 == External links == {{Commonscat|Beaks}} * http://www.peteducation.com/article.cfm?cls=15&cat=1829&articleid=2752 * http://www.birdsnways.com/wisdom/ww53eiv.htm * http://qp-society.com/qpserc/beak.html [[Category:Bird topography]] [[ca:Bec]] [[cs:Zobák]] [[da:Næb]] [[de:Schnabel]] [[es:Pico (zoología)]] [[eo:Beko]] [[fr:Bec]] [[fy:Snaffel]] [[ko:부리]] [[hr:Kljun]] [[it:Becco]] [[he:מקור]] [[ka:ნისკარტი]] [[la:Rostrum (beccus)]] [[lt:Snapas]] [[hu:Csőr]] [[nl:Snavel]] [[ja:くちばし]] [[no:Nebb]] [[nn:Nebb]] [[oc:Bèc]] [[pl:Dziób (zoologia)]] [[pt:Bico]] [[qu:Chhukruna]] [[ru:Клюв]] [[scn:Pizzu (mascidda)]] [[simple:Beak]] [[sk:Zobák]] [[fi:Nokka]] [[sv:Näbb]] [[tr:Kuş gagası]] [[uk:Дзьоб]] [[zh:喙]]