Energy Requirements

As ectotherms, turtles are better able to conserve of shift energy utilization within maintenance and production categories over endotherms.6 Through evolution of survival, turtles have learned to make subconscious "decisions" at the beginning of each feeding about whether the energy gained will exceed the energy expended.6


In the first year of life, the female midland painted turtle metabolizes 96.2kJ of energy (averaging 0.264kJ/day); 49% of that energy goes to rest, 44% goes to activity, 6% to growth and 1% to storage.3 When the turtle reaches sexual maturity around 8 years of age, the turtle metabolizes 1591.3kJ of energy in one year (averaging 4.360kJ/day); 43% goes to rest, 38% goes to activity, 2% for growth, 15% egg production and 2% storage.3 At 14 years, the turtle metabolizes 1996.9kJ of energy in one year (averaging 5.47kJ/day); 45% goes to rest, 40% for activity, <1% for growth, 14% egg production and 0% storage.3 More detail is shown in Figure 4.

Figure 4. ME budgets for the midland painted turtle, Biology of the Reptilia3
The BMR of a 1281g midland painted turtle is 0.026 cc O2 / (g x h) at 20C.12 Daily energy expenditure (DEE), can be measured using, BMR*ME = DEE. Therefore, DEE of the midland painted turtle at 1 year old is (0.026 cc O2 / (g x h))*(96.2kJ) which equates to 2.5kJ.3 and 12 The same method was used to determine DEE at sexual maturity [(0.026 cc O2 / (g x h))*(1591.3kJ)] of 41.37kJ and a DEE of 51.92kJ at 14 years of age.3 and 12 As shown above, the DEE does not range must once sexual maturity is reached.


As calculated under the "Nutrition" page, the GE for one golden apple snail is 2.32kJ/g. According to these values, a midland painted turtle at age 8 would need to consume approximately 18g of golden snails (41.37kJ/2.32kJ/g). Assuming a snail weighs 2g, that would mean the turtle would need to consume 9 golden snails for this year of its life. As no metabolizable energy was found on any type of snail, the assumption has been made that this calculation is an underestimation of the amount of snails needed to meet the energy demands of the midland painted turtle. 

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