The pseudobranch, also pseudobranchia is the reduced first

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

arch of a

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

(on the inner surface of the opercle, near the junction of the preopercle) as well as a reduced "false" gill in some gastropods. In teleost fish, the pseudobranchs are mostly without respiratory function, and in elasmobranchs they are the gill arch of the

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

. The function of the pseudobranch is unknown, but it is believed that it supplies highly oxygenated blood to the optic choroid and retina and may have baroreceptor (pressure) and thermoregulation functions. It may also be a site of oxygen chemoreception.

External links

Picture of trout pseudobranch

Pseudobranch description incl. picture

References

Fish anatomy {{vertebrate-anatomy-stub