Description
Return tibiaFemurRatio = tibia/femur, tarsusTibiaRatio = tarsus/tibia and distalFraction = tarsus/(femur+tibia+tarsus).
Insect morphology measurements depend on landmark definitions, image scale and specimen condition. A length ratio can be dimensionless while a calibrated coordinate has physical units; neither arithmetic operation validates anatomical correspondence or preservation assumptions.
Return tibiaFemurRatio = tibia/femur, tarsusTibiaRatio = tarsus/tibia and distalFraction = tarsus/(femur+tibia+tarsus).
When to use this tool
Use Arthropod Leg Segment Ratio when checking a supplied morphological measurement, calibration or length ratio.
How to use the tool and how it works
- Enter femur, tibia, tarsus. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read tibiaFemurRatio, tarsusTibiaRatio, distalFraction. Use the output convention below.
Require positive femur and tibia lengths and nonnegative tarsus. Return tibiaFemurRatio = tibia/femur, tarsusTibiaRatio = tarsus/tibia and distalFraction = tarsus/(femur+tibia+tarsus).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| femur | Femur | Required. Finite number; strictly above 0. |
| tibia | Tibia | Required. Finite number; strictly above 0. |
| tarsus | Tarsus | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| tibiaFemurRatio | Tibia Femur Ratio | Required. Finite number. |
| tarsusTibiaRatio | Tarsus Tibia Ratio | Required. Finite number. |
| distalFraction | Distal Fraction | Required. Finite number. |
{
"input": {
"femur": 4,
"tibia": 3,
"tarsus": 1
},
"output": {
"tibiaFemurRatio": 0.75,
"tarsusTibiaRatio": 0.3333333333333333,
"distalFraction": 0.125
}
}Limitations and assumptions
- Use one length unit and compatible segment definitions. The ratios do not identify taxa or account for preservation, posture or measurement error.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use verified imaging calibration and appropriate specimen methods for anatomical interpretation, and propagate uncertainty when measurement precision matters.
References
Similar or alternative tools
- Insect Antennal Segment Length Ratio
Summarize segment lengths with a selected segment’s total-length fraction and the first longest index.
- Insect Body Length Preservation Factor
Convert preserved length into an original-length estimate and a supplied retention-factor uncertainty envelope.