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The gills are composed of comb-like filaments, the gill lamellae, which help increase their surface area for oxygen exchange. [5] When a fish breathes, it draws in a mouthful of water at regular intervals. Then it draws the sides of its throat together, forcing the water through the gill openings, so it passes over the gills to the outside.
The gill arches of bony fish typically have no septum, so that the gills alone project from the arch, supported by individual gill rays. Some species retain gill rakers . Though all but the most primitive bony fish lack a spiracle, the pseudobranch associated with it often remains, being located at the base of the operculum.
Gill arches supporting the gills in a pike. Branchial arches or gill arches are a series of paired bony/cartilaginous "loops" behind the throat (pharyngeal cavity) of fish, which support the fish gills. As chordates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arches varies between taxa.
The water is circulated by the action of the gills. Usually water enters the mantle cavity through the inhalant siphon, moves over the gills, and leaves through the exhalant siphon. The water current is utilized for respiration, but also for filter feeding, excretion, and reproduction.
The first set of these elements surrounded the mouth to form the jaw. The upper portion of the second embryonic arch supporting the gill became the hyomandibular bone of jawed fish, which supports the skull and therefore links the jaw to the cranium. [32] The hyomandibula is a set of bones found in the hyoid region in most fishes.
gill arches The bony arches to which the gills are attached. gill cover A bony flap that covers the gills; another name for the operculum. gill filaments A series of projections along the posterior edge of the gill arch, the site of gas exchange. gill membranes Membranes covering the gill openings, attached to the branchiostegals. gill opening
In this spider diagram, the position of the book lungs is labelled 1. Spider book lungs (cross section) Internal anatomy of a female spider, book lungs shown in pink A book lung is a type of respiration organ used for atmospheric gas-exchange that is present in many arachnids, such as scorpions and spiders.
External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animal's head. The axolotl has three pairs of external ...