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Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
Jaws allow fish to eat a wide variety of food, including plants and other organisms. Fish ingest food through the mouth and break it down in the esophagus. In the stomach, food is further digested and, in many fish, processed in finger-shaped pouches called pyloric caeca, which secrete digestive enzymes and absorb nutrients.
Gas exchange in reptiles still occurs in alveoli, but reptiles do not possess a diaphragm, therefore ventilation occurs via a change in the volume of the body cavity which is controlled by contraction of intercostal muscles in all reptiles except turtles. In turtles, contraction of specific pairs of flank muscles governs inspiration or ...
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 ...
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.
The surrounding egg white floats perfectly around the yolk, membrane intact. One of the divers was even able to make the egg 'dance' around by manipulating the current of the water around it.
Various fish, as well as polychaete worms and even crabs, are specialized to take advantage of the constant flow of water through the cloacal respiratory tree of sea cucumbers while simultaneously gaining the protection of living within the sea cucumber itself. At night, many of these species emerge from the anus of the sea cucumber in search ...
the allantois which among avians stores embryonic waste and assists with the exchange of carbon dioxide with oxygen as well as the resorption of calcium from the shell, and the chorion which surrounds all of these and in avians successively merges with the allantois in the later stages of egg development to form a combined respiratory and ...