The formation of biomineralized skeletons implies more or less control of internal pH, and its relation to CO32- concentration depending on the complexity of the biomineralization mechanisms; greater physiological control over pH balance (an essential characteristic for mineralization with phosphate) could explain the survival of most organisms with relatively complex skeletons from extinction during the Permian: the acquisition of more refined mechanisms for pH control intrinsic to mineralization could have provided metabolic resources capable of compensating the high respiratory cost in environments with high concentrations of carbon dioxide.
Figure 1.24:Physiological acquisitions of cells relating to biomineralization: The excretion of metabolites permitted the development of the first ion transport mechanisms, responsible for diverse methods of ion control. The metabolic necessities relate intrinsically to the need for internal pH maintenance. The endosymbiosis, responsible for the integration of different intracellular tasks, also stimulated the selection of individuals with a karyotheca, and the first membrane modifications, relative to biomineralization, probably avoided it, considering the supersaturated oceans. Later, the increasing control of biomineralizing mechanisms selected individuals with more physiological self-control, refining pH control.
