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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.
Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers (operculum) on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including ...
Microscopic image of two ionocytes in a gill An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill , insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs. [ 1 ]
The skin of the fish are a part of the integumentary system, which contains two layers: the epidermis and the dermis layer. The epidermis is derived from the ectoderm and becomes the most superficial layer that consists entirely of live cells, with only minimal quantities of keratin .
The cytostome (cell mouth) is on the surface that faces away from the host; this is termed the oral surface. The other side, or aboral surface, attaches to the skin of the host or other substrate. There is a spiral of cilia leading towards the cytostome and several rings of cilia at the periphery of the cell, responsible for creating adhesive ...
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.
Inside the gill slits, are long projection-like structures called gill filaments. Gill filaments are lateral to the gill arches and have a high surface area, where they form folds inside the gill slits. Lamellae in the gill slits are thin, membrane folds that have access to blood supplies via arteries and are the site of gas exchange.
In fish gills, there are two types of lamellae, primary and secondary. The primary gill lamellae (also called gill filament) extends from the gill arch, and the secondary gill lamellae extends from the primary gill lamellae. Gas exchange primarily occurs at the secondary gill lamellae, where the tissue is notably only one cell layer thick.