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A dewlap is a flap of skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 that hangs beneath the lower jaw of tetrapod
Tetrapod

Tetrapods are vertebrate animals having four feet, legs or leglike appendages. Amphibians, reptiles, dinosaurs/birds, and mammals are all tetrapods, and even the limbless snakes are tetrapods by descent....
s, that is, amphibian
Amphibian

Amphibians , such as frogs, toads, salamanders, newts and caecilians, are cold-blooded animals that metamorphose from a juvenile, water-breathing form to an adult, air-breathing form....
s, reptile
Reptile

Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded vertebrates that have skin covered in scale as opposed to hair or feathers....
s, bird
Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
s, mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s and their relatives. While the term is usually used in this specific context, it can also be used to include other structures occurring in the same body area with a similar aspect, such as those caused by a double chin
Double chin

A double chin is a phenomenon caused by a layer of subcutaneous fat around the neck that sags down and creates a wrinkle, making the owner appear to have a second chin....
 or the sub-mandibular vocal sac
Vocal sac

The vocal sac is the flexible membrane of skin possessed by most male frogs. The purpose of the vocal sac is usually as an amplification of their mating or advertisement call....
 of a frog
Frog

Frogs are amphibians in the order Anura , formerly referred to as Salientia . The name frog derives from Old English language frogga, , cognate with Sanskrit plava , probably deriving from Proto-Indo-European language praw = "to jump"....
. In a more general manner, the term refers to any pendulous mass of skin, such as a fold of loose skin on an elderly person
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
's neck, or the wattle
Wattle (anatomy)

A wattle is a fleshy dewlap or caruncle hanging from various parts of the head or neck in several groups of birds, goats and other animals.File:Rooster portrait2.jpg...
 of a bird
Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
.






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A dewlap is a flap of skin
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 that hangs beneath the lower jaw of tetrapod
Tetrapod

Tetrapods are vertebrate animals having four feet, legs or leglike appendages. Amphibians, reptiles, dinosaurs/birds, and mammals are all tetrapods, and even the limbless snakes are tetrapods by descent....
s, that is, amphibian
Amphibian

Amphibians , such as frogs, toads, salamanders, newts and caecilians, are cold-blooded animals that metamorphose from a juvenile, water-breathing form to an adult, air-breathing form....
s, reptile
Reptile

Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded vertebrates that have skin covered in scale as opposed to hair or feathers....
s, bird
Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
s, mammal
Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s and their relatives. While the term is usually used in this specific context, it can also be used to include other structures occurring in the same body area with a similar aspect, such as those caused by a double chin
Double chin

A double chin is a phenomenon caused by a layer of subcutaneous fat around the neck that sags down and creates a wrinkle, making the owner appear to have a second chin....
 or the sub-mandibular vocal sac
Vocal sac

The vocal sac is the flexible membrane of skin possessed by most male frogs. The purpose of the vocal sac is usually as an amplification of their mating or advertisement call....
 of a frog
Frog

Frogs are amphibians in the order Anura , formerly referred to as Salientia . The name frog derives from Old English language frogga, , cognate with Sanskrit plava , probably deriving from Proto-Indo-European language praw = "to jump"....
. In a more general manner, the term refers to any pendulous mass of skin, such as a fold of loose skin on an elderly person
Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
's neck, or the wattle
Wattle (anatomy)

A wattle is a fleshy dewlap or caruncle hanging from various parts of the head or neck in several groups of birds, goats and other animals.File:Rooster portrait2.jpg...
 of a bird
Bird

Birds are wing, Bipedalismal, endothermic , vertebrate animals that lay egg . There are around 10,000 living species, making them the most numerous tetrapod vertebrates....
. There are also dewlaps on dogs such as the English Springer Spaniel
English Springer Spaniel

The English Springer Spaniel is a dog breed of gun dog traditionally used for flushing and retrieving game. It is one of many spaniel breeds....
, the Basset Hound
Basset Hound

The Basset Hound is a short-legged dog breed of dog of the hound family. They are scent hounds, bred to hunt rabbits by scent. Their sense of smell for tracking is second only to that of the Bloodhound....
 or the Mastiff
Mastiff

Mastiff may refer to:...
. The dewlap is also found on female rabbits, such as the New Zealand white rabbit
New Zealand white rabbit

New Zealand white rabbits are 100% United States breed despite their name. In 1916, W.S. Preshaw bred the first litter of New Zealand white rabbits with a plan to produce a rabbit that would be excellent for meat and fur trade....
. While pregnant, the female rabbit will pluck fur from the dewlap to line a nest for her babies. Although these masses can be referred to as dewlaps, they are formed by stored fat. The Dewlap is also seen in both genders of moose
Moose

File:Alces alces NA.svgThe moose or elk , , is the largest Extant taxon species in the deer family . Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a "twig-like" configuration....
, which may or may not be an indicator of status.

Reptiles, most notably the anole
Polychrotidae

Polychrotidae is a family of lizards commonly known as Anoles . Some authorities place the anoles in subfamily Polychrotinae of the family Iguanidae....
 species of lizard
Lizard

Lizards are a large and widespread group of squamate reptiles, with nearly 5,000 species, ranging across all continents except Antarctica as well as most oceanic island chains....
, have large skin dewlaps under their neck which they can extend and retract. The dewlaps are usually of a different color from the rest of their body and can be enlarged to make the lizard seem much bigger than it really is, especially when warding off predators. Males use the dewlap to intimidate rivals and to attract females during mating season. Despite the male lizard dewlap being much larger in size, female anoles do indeed possess a dewlap as well. These uses for the dewlap work much in the same way as the neck frill
Neck frill

Neck frill is the popular term for the relatively extense margin seen on the back of the heads of reptiles with either a bone support such as those present on the skulls of dinosaurs of the suborder Marginocephalia or a cartilage one as in the Frill-necked Lizard....
 on a frill-necked lizard
Frill-necked Lizard

The Frill-necked Lizard, or Frilled Lizard also known as the Frilled Dragon, is so called because of the large ruff of skin which usually lies folded back against its head and neck....
, with the lizard extending its neck frill for much of the same reasons. However, it is not known if the dewlap is used in thermoregulation
Thermoregulation

Thermoregulation is the ability of an organism to keep its core temperature within certain boundaries, even when the surrounding temperature is very different....
 like the neck frill is.

Lizards who have dewlaps usually accompany their dewlap enlargement with head bobs and movement. Scientists are unsure about what this is meant to communicate, but it is prevalent when the lizards are courting.

In humans, the formation of a dewlap is prevented by the attachment of the deep cervical fascia
Deep cervical fascia

The deep cervical fascia lies under cover of the Platysma, and invests the neck; it also forms sheaths for the carotid vessels, and for the structures situated in front of the vertebral column....
 to the hyoid bone
Hyoid bone

The hyoid bone is a horseshoe shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind....
.

See also

  • Crest
    Crest (bird)

    The crest is a prominent feature exhibited by several bird and dinosaur species on their heads. Fleshy crests are called cockscombs; this article discusses feather crests....
  • Double chin
    Double chin

    A double chin is a phenomenon caused by a layer of subcutaneous fat around the neck that sags down and creates a wrinkle, making the owner appear to have a second chin....
  • Neck frill
    Neck frill

    Neck frill is the popular term for the relatively extense margin seen on the back of the heads of reptiles with either a bone support such as those present on the skulls of dinosaurs of the suborder Marginocephalia or a cartilage one as in the Frill-necked Lizard....
  • Wattle
    Wattle (anatomy)

    A wattle is a fleshy dewlap or caruncle hanging from various parts of the head or neck in several groups of birds, goats and other animals.File:Rooster portrait2.jpg...