gill

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gill

(gĭl)
n.
Zoology The respiratory organ of most aquatic animals that obtain oxygen from water, consisting of a filamentous structure of vascular membranes across which dissolved gases are exchanged.

gilled adj.

gill

  1. the respiratory organ of aquatic animals. External gills, as in tadpoles, are produced by the embryonic ECTODERM; internal gills, as in fish, are developed from the pharynx and are thus endodermal (see ENDODERM). Gills are usually well supplied with blood vessels, and interchange of oxygen and carbon dioxide takes place across the extensive surface area (see COUNTERCURRENT EXCHANGE). Gills also occur in many invertebrates, for example, in insects such as the caddis fly larva and molluscs such as oysters. Occasionally, unusual structures act as gills, for example, the walls of the rectum in certain dragonfly nymphs, water being pumped in and out via the anus.
  2. the spore-carrying lamellae in basidiomycete fungi, located underneath the cap or ‘pileus’.

gill

external breathing apparatus of fish. Very susceptible to a wide range of diseases.
Enlarge picture
Gill system of fish. By permission from Aspinall V, O'Reilly M, Introduction toVeterinary Anatomy and Physiology, Butterworth Heinemann, 2004

gill disease
an infectious disease of aquarium and salmonid species of fish caused by Flavobacterium bronchiophila. Also in Crassostrea angulata caused by an iridovirus and in larval shrimp caused usually by a Leucothrix spp. bacterium. Chronic, proliferative inflammation causes the gill filaments to be swollen and may be clubbed or fused. Called also bacterial gill disease.
gill parasites
the following external parasites are commonly found on the gills, and elsewhere on the skin, in aquarium fish: Gyrodactylus elegans—a monogenetic fluke; Diplozoon barbi, D. paradoxum—monogenetic flukes; Ergasilus sieboldi—crustaceans. Freshly caught seahorses may carry the crustacean Argulus spp. Pond fish may carry the anchor worm Lernaea spp. These are all visible with the naked eye and can be removed manually.
References in periodicals archive ?
Lo CM, Morand S (2000) Spatial distribution and coexistence of monogenean gill parasites inhabiting two damselfishes from Moorea island in French Polynesia.
Hanek G, Fernando CH (1978) Seasonal dynamics and spatial distribution of Urocleidus ferox Mueller, 1934 gill parasites of Lepomis gibbosus (L).
A total of 237 northern rock soles from 8 trawl hauls was examined at sea for gill parasites: 90 fish appeared to have at least one gill parasite and their heads were frozen at sea (Table 2).
Of the two gill parasites examined in detail, Naobranchia occidentalis was more prevalent and caused more intense infestations than did Nectobrachia indivisa.
Bilong Bilong CF, Atyame Ntem CM, Njine T (2004) Structure of the guild of monogenean gill parasites of fish Hemichromis fasciatus in Yaounde municipal lake.