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The great majority of bony fish species have five pairs of gills, although a few have lost some over the course of evolution. The operculum can be important in adjusting the pressure of water inside of the pharynx to allow proper ventilation of the gills, so that bony fish do not have to rely on ram ventilation (and hence near constant motion ...
Branchial arches, or gill arches, are a series of paired bony "loops" that support the gills in fish. As gills are the primitive feature of vertebrates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arches varies between taxa. In jawed fish, the first arch pair (mandibular arches) develops into the jaw.
Red represents a higher value (e.g. of temperature or the partial pressure of a gas) than blue so the property being transported in the channels flows from red to blue. In fish a countercurrent flow (lower diagram) of blood and water in the gills is used to extract oxygen from the environment. [6] [7] [8] All basal vertebrates breathe with gills.
The main bodies of the cells lie outside of the pigment cup, while the cilia extend into the pigment cup before turning and exiting. The cells bear the opsin c-opsin 1, except for a few which carry c-opsin 3. [60] [62] The Row 2 cells are serotonergic neurons in direct contact with Row 1 cells. Row 3 and 4 cells are also neurons.
The second arch becomes the hyoid and jaw support. [1] In fish, the other posterior arches contribute to the branchial skeleton, which support the gills; in tetrapods the anterior arches develop into components of the ear, tonsils, and thymus. [3] The genetic and developmental basis of pharyngeal arch development is well characterized.
The gills of fish form a number of slits connecting the pharynx to the outside of the animal on either side of the fish behind the head. Originally there were many slits, but during evolution, the number reduced, and modern fish mostly have five pairs, and never more than eight. [8]
It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. [1] In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on ...
Fish – any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate 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.