Aestivation in amphibians, reptiles, and lungfish

Abstract

Some regions of the world have very limited variations in temperature during the year. Adverse conditions such as lack of appropriate food items and/or the drying out of shallow lakes may induce a state of torpor. This is different from hibernation, which involves a reduction of temperature. Torpor is characterized by a cessation of feeding, and eventually lack of movement. In addition, tissue metabolism and cardiac activity become downregulated, mainly by reduced cardiac frequency. The state of torpor occurs in some amphibians, reptiles and lungfish, and the transition also involves increases in CO2, accompanied by reduced O2 levels. African lungfish have records of surviving in a cocoon with up to 7 years without food intake, but amphibians and reptiles survive in torpor for several months.