Search

The fourth part of chapter 5 of the book "Primitive Fishes," edited by David J. McKenzie, Anthony P. Farrell, and Colin J. Brauner is presented. It explores the delivery and elimination of carbon dioxide in the respiratory system of primitive fishes. It highlights the general model of carbon dioxide delivery and excretion.

The fifth part of chapter 5 of the book "Primitive Fishes," edited by David J. McKenzie, Anthony P. Farrell, and Colin J. Brauner is presented. It explores the way primitive fishes such as the primitive ray-finned, the primitive lobed-finned, and the jawless fishes compete with other fishes. It also discusses the evolution of vertebrate blood oxygen and carbon dioxide delivery characteristics.

The third part of chapter 5 of the book "Primitive Fishes," edited by David J. McKenzie, Anthony P. Farrell, and Colin J. Brauner is presented. It explores the blood oxygen transport in the respiratory system of primitive fishes. It highlights the general principles of hemoglubin function, the factors that affect the arterio venous oxygen difference, and a survey of extant primitive fishes.

The second part of Chapter 5 of the book "Primitive Fishes," edited by David J. McKenzie, Anthony P. Farrell, and Colin J. Brauner is presented. It explores the partitioning of oxygen and carbon dioxide exchange across the respiratory surface in primitive fishes. It also highlights the primitive ray-finned fishes, the lobe-finned fishes and the jawless fishes.

Gas exchange is a prerequisite of vertebrate life. In terms of structural and functional diversity and habitats occupied, extant teleosts clearly outcompete extant primitive fishes; however, there are a few aspects related to gas exchange that may have contributed to the survival of these primitive fishes. Most of the primitive fishes either have the ability to breath air, have the ability to tolerate aerial exposure (and in some cases estivate), or are tolerant to aquatic hypoxia. Many of the bimodal breathers retain fully functional gills, which at times allow strictly aquatic breathing over prolonged periods which may be important for aerial predator avoidance or surviving ice cover in temperate climates. While air breathing is important for surviving aquatic hypoxia, it is also important in enhancing O2 uptake during exercise. Living primitive fishes occupy strategic positions in the evolutionary tree of vertebrates and may shed light on the evolution of blood O2 and CO2 transport characteristics. Evolutionary reconstruction indicates that the increase in the Bohr-Haldane eVect in primitive ray-finned fishes was followed first by a gradual increase in the magnitude of the Root eVect and then a gradual reduction in specific Hb buVer value. This was followed by the evolution of a choroid rete mirabile and ocular O2 secretion in the last common ancestor of Amia calva and teleosts. Finally, the adrenergic red blood cell Na+/H+ exchanger was never present in primitive ray-finned fishes or primitive teleosts and only evolved in advanced teleosts. No such evolutionary trends are observed in primitive lobe-finned fishes. [ABSTRACT FROM AUTHOR]

An abstract of the article "Gas Transport and Exchange," by C.J. Brauner and M. Berenbrink is presented.