Physiological adaptations in Bat

        A few bats are heterotherm , because , they may act as poikilothermic during hibernation/ roosting ; or or at active state  homeothermic . It maintains a  few  number of physiological adaptations  which are as follows:

(1) Adaptations in circulatory system: 

(i) Bat's heart is 3 times larger in size as compared to other terrestrial mammal of the same relative size , hence , it pumps more oxygen when in flight .

(ii)The heart rate in a microbat is about 1000 beats/min when active , but it may be reduced to minimum level during its hibernation time . It also increased at the onset of flight also.

(iii) It increases Hb concentration when active .

(iv) The venomotion is strong to maintain the flow of deoxygenated blood to the left auricle .

(v)    Patagium membrane is extreamly thin  , it's surface area is 85% of total body surface area and the subcutaneous blood vessels are very close to the surface to give extreme O² & CO² exchange facilities for the high energy demand during flight .

(2) Adaptations in respiratory system:

(i)The alveolar capillary membrane is very thin , alveolar surface area & pulmonary blood volume ,etc are vary high.

(ii) Highly vascularised patagium helps in gaseous exchange when active .

(iii) Bats increase their respiration rate at the onset of flight(3--9.6/sec) to maintain high energy demand.

(3) Adaptations in digestive system :

      On the basis of feeding habit digestive enzymes also vary:

(i) Chitinase in insectivorous bats

(ii) Maltase is absent in blood eating bats.

(iv) Nectivorous and furgivorous bats have high amount of maltase and sucrase .

(4) Adaptations in Renal system :

(i) In carnivorous & blood eating bats renal corex is thin & renal papillae are long to excreate concentrated urine.

(ii) In furgivorous bats renal cortex turn thick and conical papillae turn short to retain electrolyte .

(5) Adaptations for echolocation :

(i) Larger bats use low frequency and smaller bats use high frequency for echolocation to detect prey.

(6) Adaptation for Thermoregulation :

(i) It can loose body  heat when patagium is extented (due to high number of blood vessels )

(ii)Small sized nat consume more food to maintain homoeothermy.

(iii) A bat use it's saliva to be cool during extreme heat , in addition a megabat does wing -fanning  also .

(iv) A bat reduces 99.6% of it's body temp., i.e. virtually to ambient level ,  during hibernation and torpor also .

(7)Adaptation in metabolism rate:

       A bat reduces the metabolism rate to extreme low level during hibernation time .