Researched and devised by Dr. Oliphant Jackson, the Jackson ratio is a method of determining whether a member of the tortoise species Testudo graeca or Testudo hermanni is maintaining its optimum bodyweight, which is necessary for a successful hibernation. [1]
Calculation
The Jackson ratio is calculated by taking the weight of the tortoise in grams and dividing it by the cube of the length of the tortoise's carapace in centimeters. [1] This is essentially a value of the density of the tortoise in g/cm3. The optimal value for this ratio is 0.21 with a range of 0.18–0.22 being acceptable for hibernation. Values significantly less than this indicate an underweight tortoise and larger values are indicative of overweight tortoises.
The Jackson ratio is expressed as a graph of minimum and optimum weights for a given carapace length. This exhibits the same principle without the maths.
References
- ^ a b "Jackson Ratio for Tortoises". Tortoise Protection Group. Retrieved 2017-02-24.
- ULf Edqvist. "Tortoise Trust Web - The Jackson Ratio Graph - Inappropriate Use". Tortoisetrust.org. Retrieved 2017-02-24.
- A. C. Highfield. "Tortoise Trust Web - How to Measure your Tortoise". Tortoisetrust.org. Retrieved 2017-02-24.
- "Heosemys grandis forum - Jackson ratio". Heosemys.org. Retrieved 2017-02-24.
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