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Such organisms (frogs, for example) rely on environmental heat sources, [3] which permit them to operate at very economical metabolic rates. [ 4 ] Some of these animals live in environments where temperatures are practically constant, as is typical of regions of the abyssal ocean and hence can be regarded as homeothermic ectotherms.
A eurytherm is an organism, often an endotherm, that can function at a wide range of ambient temperatures. [1] To be considered a eurytherm, all stages of an organism's life cycle must be considered, including juvenile and larval stages. [2]
The only known living homeotherms are mammals and birds, as well as one lizard, the Argentine black and white tegu. Some extinct reptiles such as ichthyosaurs, pterosaurs, plesiosaurs and some non-avian dinosaurs are believed to have been homeotherms. Tachymetabolism [c] maintains a high "resting" metabolism. In essence, tachymetabolic ...
Another example would be the case of the fairy prion (Pachyptila turtur) that forms a close association with a medium-sized reptile, the tuatara (Sphenodon punctatus). [16] These reptiles share the burrows made by the birds, and often stay when the birds are present which helps maintain a higher body temperature. [ 16 ]
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation.
For example, some insects synthesize cryoprotectants such as polyols and sugars, which reduce the whole body SCP. Although polyols such as sorbitol , mannitol , and ethylene glycol can also be found, glycerol is by far the most common cryoprotectant and can be equivalent to ~20% of the total body mass. [ 17 ]
The fact that the same evolutionary character evolved independently in two different lineages after their last known common ancestor means that thermogenic processes are classified as an example of convergent evolution. However, while both clades are capable of performing thermogenesis, the biological processes involved are different.
The activity of metabolic enzymes varies with temperature, so temperature control is vital for any organism, whether endothermic or ectothermic. Organisms can be categorized as poikilotherms (poikilo – changing), which are tolerant of internal temperature fluctuations, and homeotherms (homeo – same), which must maintain a constant core ...