gill

Anatomical surface structure found in many aquatic organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide. The microscopic structure of a gill is such that it presents a very large surface area to the external environment. Gills usually consist of thin filaments of tissue, branches, or slender tufted processes which have a highly folded surface to increase surface area. A high surface area is crucial to the gas exchange of aquatic organisms as water contains only 1/20 parts dissolved Oxygen compared to air. With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood or coelomic fluid, from which gases are exchanged through the thin walls. Oxygen is carried by the blood to other parts of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians.

Type Organ
Système corporel Respiratory
Structure parente organ

Sous-structures

papula Organ pharyngeal arch derived gill Organ pharyngeal gill Organ

Questions fréquentes

What is a gill?
A gill is a respiratory organ found in aquatic animals that extracts dissolved oxygen from water. Gills are present in fish, larval amphibians (tadpoles), aquatic insects, crustaceans, mollusks, and other invertebrates.
How do gills extract oxygen from water?
Gills work by passing water over a highly vascularized surface with thin filaments and lamellae. Oxygen diffuses from the water across the thin epithelium into the blood, while carbon dioxide diffuses in the opposite direction, a process enhanced by countercurrent exchange in bony fish.
What is the structural adaptation that makes gills efficient for gas exchange?
Gills have a very large surface area achieved through numerous thin filaments (primary lamellae) bearing even smaller secondary lamellae. This extensive surface, combined with the thin diffusion barrier and rich blood supply, allows efficient oxygen extraction from water.
How do fish gills differ from those of larval amphibians?
Fish typically have internal gills enclosed in gill chambers covered by an operculum, allowing unidirectional water flow. Larval amphibians (tadpoles) and some aquatic salamanders have external feathery gills that protrude from the body surface and are eventually resorbed during metamorphosis.
What is the developmental origin of vertebrate gills?
Vertebrate gills develop from the pharyngeal (branchial) arches, which are paired embryonic structures derived from neural crest cells and lateral plate mesoderm. In aquatic vertebrates, these arches develop into functional gill arches; in terrestrial vertebrates, they form other head and neck structures.

Structures associées

muscle of larynx laryngeal muscle nasal-associated lymphoid tissue NALT nasal bone nasal bones nasal bridge nasal cartilage cartilage of nose nasal cavity respiratory epithelium nasal diverticulum false nostril nasal hair hair of nose

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Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.