Appendage

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Appendage

An appendage in the broadest sense is an additional or subsidiary part existing on, or added to, something which can generally still function if the appendage has never existed or is later provided or grown, or will still perform a primary function if the appendage is removed.

Biological context
An appendage is an external body part, or natural prolongation, that protrudes from an organism

Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
's body, such as a vertebrate

Vertebrate

Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
's limb

Limb (anatomy)

A limb is a jointed, or prehensile , appendage of the human or other animal body.Most animals use limbs for locomotion, such as walking, running, or climbing....
s.

In invertebrate

Invertebrate

An invertebrate is an animal lacking a vertebral column. The group includes 98% of all animal species ? all animals except those in the Chordate subphylum vertebrate ....
biology

Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
, "appendage" is a general term that covers any of the homologous

Homology (biology)

In evolutionary biology, homology refers to any similarity between characteristics that is due to their common descent. The word homologous derives from the ancient Greek ??????e??, 'to agree'....
body parts that may extend from a body segment.

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Encyclopedia

Biological context

An appendage is an external body part, or natural prolongation, that protrudes from an organism

Organism

Vertebrate

Limb (anatomy)

A limb is a jointed, or prehensile , appendage of the human or other animal body.Most animals use limbs for locomotion, such as walking, running, or climbing....
s.

In invertebrate

Invertebrate

An invertebrate is an animal lacking a vertebral column. The group includes 98% of all animal species ? all animals except those in the Chordate subphylum vertebrate ....
biology

Biology

Homology (biology)

Antenna (biology)

Antennae are paired appendages connected to the front-most morphogenesis of arthropods. In crustaceans, they are biramous and present on the first two segments of the head, with the smaller pair known as antennules....
, mouthparts

Mouthparts

The mouthparts of arthropods have evolution into a number of forms, each adaptation to a different style or mode of feeding. Most mouthparts represent modified, paired appendages, which in ancestral forms would have appeared more like legs than mouthparts....
(including mandible

Mandible

The mandible or inferior maxillary bone forms the lower jaw and holds the lower tooth in place. It also refers to both the upper and lower sections of the beaks of birds....
s, maxilla

Maxilla

The maxilla is a fusion of two bones along the palate fissure that form the upper jaw. This is similar to the mandible, which is also a fusion of two halves at the mental symphysis....
e and maxillipeds), wings

Insect wing

Insect wings are outgrowths of the insect exoskeleton that enable insects to Insect flight. They are found on the second and third thorax segments , and the two pairs are often referred to as the forewings and hindwings, respectively, though a few insects lack hindwings, even rudiments....
, elytra

Elytron

An elytron is a modified, hardened forewing of certain insect orders, notably beetles and true bugs . An elytron is sometimes also referred to as a shard....
, gill

Gill

A gill is an anatomical structure found in many aquatic ecosystem organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide....
s, walking legs

Arthropod leg

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus , ischium, metatarsus, carpus, dactylus , patella....
(pereiopods), swimming legs (pleopods), sexual organs (gonopods), and parts of the tail (uropods). Typically, each body segment carries one pair of appendages.

Appendages may be uniramous, as in insect

Insect

Insects are the biggest class of arthropods and the only ones with wings. They are the most diverse group of animals on the planet. They are most diverse at the equator and their diversity declines toward the poles....
s and centipede

Centipede

For information about the old arcade game, see Centipede .Centipedes are arthropods belonging to the class Chilopoda and the Subphylum Myriapoda....
s, where each appendage comprises a single series of segments, or it may be biramous, as in many crustaceans, where each appendage branches into two sections. Triramous (branching into three) appendages are also possible.

All arthropod appendages are variations of the same basic structure (homologous), and which structure is produced is controlled by "homeobox

Homeobox

A homeobox is a DNA sequence found within genes that are involved in the regulation of patterns of development in animals, fungus and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family....
" genes. Changes to these genes have allowed scientists to produce animals (chiefly Drosophila melanogaster
Drosophila melanogaster

Drosophila melanogaster is a two-winged insect that belongs to the Diptera, the Order of the Fly. The species is commonly known as the Drosophilidae or vinegar fly, and is one of the most commonly used model organisms in biology, including studies in genetics, physiology and Life history theory....
) with modified appendages, such as legs instead of antennae.matt

Linguistic context

In British English

British English

British English or UK English is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere....
, depending on the surrounding context, "appendage" might imply that the added words to which it refers give a more precise meaning to a name or description or else it might be used in a derogatory sense to describe an addition which appears to serve no useful function.