Digestive And Metabolic Adaptations to Heat

How Desert Animals Use Digestion And Metabolism In Hot Climates

May 22, 2009

Arid climates can be unforgiving. Mammals have adapted ways to cope by minimizing water and metabolic requirements.

Desert mammals are required to deal with a variance in temperature throughout the day. By day the temperature can be scorching and often with little shaded cover, and in the evenings when the sun goes down, there is a drop in temperature. Desert mammals have evolved various mechanical and behavioural adaptations to cope with the potential water loss and heat stress due to the hot climate and with minimal free water availability.

How Do Desert Animals Use Digestion And Metabolism To Cope With Hot Climates?

Goats living in harsh environments have adapted to such areas by minimizing their maintenance and water requirements with low body mass and low metabolic requirements. This ability to reduce metabolism means that the goats can survive in hot climates despite often-prolonged periods of limited food and water availability.

These desert goats have adapted a skillful grazing behaviour and an efficient digestive system. The rumen serves as a huge fermentation vat and water reservoir. They then utilize stored water (in rumen) when dehydrated, and the rumen acts as a container for the ingested water upon rehydration.

The physiological features of ruminants include large salivary glands, large absorptive area of the rumen epithelium and the ability to change the volume of the foregut in response to environmental changes. The rumen, salivary glands and the kidneys work together in the regulation of water intake and water distribution following dehydration and rapid rehydration in desert goats.

There is a widespread occurrence of dwarfism among goats in adverse environments. This is known as the “rule of Bergmann”. It claims that “in warm-blooded animals, races from warm regions are smaller the races from cold regions”. This morphological variation in animals in ambient temperatures is a generalization, although, the larger body surfaces of smaller mammals do serve as efficient heat dissipaters in warm regions.

Other scientific studies suggest that body size is linked more with primary plant productivity, but it is likely to be a combination of these factors, and it has been shown that hereditary dwarfism in goats is more widespread in Africa that any other part of the world.

The habitat an animal lives in can often be quite harsh. In the desert, heat stress and dehydration are serious issues faced on a daily basis, placing demands and limitations on an animals functions and development and even causing death. Evolution has influenced the mammals that now live in these environments, like the rumen of the goat acting as a water reservoir; all desert mammals have evolved crucial and clever adaptations to deal with these stressors.

Silanikove, N, 2000, ‘The physiological basis of adaptation in goats to harsh environments’, Journal of Small Ruminent Research, vol. 35, pp. 181-193.

The copyright of the article Digestive And Metabolic Adaptations to Heat in Anatomy & Physiology is owned by Roberta Goli. Permission to republish Digestive And Metabolic Adaptations to Heat in print or online must be granted by the author in writing.