|
Attribute
|
Formula
|
Significance
|
1. |
Compression Index |
CI = BH/BW |
Higher values indicate laterally compressed fish that inhabit areas of low water velocity (Watson and Balon, 1984Watson, D.J. and Balon, E., 1984. Ecomorphological analysis of taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, vol. 25, no. 3, pp. 371-384. http://dx.doi.org/10.1111/j.1095-8649.1984.tb04885.x. http://dx.doi.org/10.1111/j.1095-8649.19...
). |
2. |
Ventral flattening Index |
VFI = ABH/BH |
Low values are typical of fish living in waters with high speed, enabling it to maintain its position without swimming (Hora, 1930Hora, S.L., 1930. Ecology, bionomics and evolution of the torrential fauna, with special reference to the organs of attachment. Philosophical Transactions of the Royal Society of London, vol. 218, no. 450-461, pp. 171-282. http://dx.doi.org/10.1098/rstb.1930.0005. http://dx.doi.org/10.1098/rstb.1930.0005...
). |
3. |
Relative height of the body |
RH = BH/SL |
Inversely related to the speed of the water and directly related to the ability to develop vertical displacements (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
4. |
Relative position of the eye |
RPE = EH/HH |
This index is related to food detection and provides information about the use of vision in predation activities (Pouilly et al., 2003Pouilly, M., Lino, F., Bretenoux, J.G. and Rosales, C., 2003. Dietary morphological relationships in a fish assemblage of the Bolivian Amazonian floodplain. Journal of Fish Biology, vol. 62, no. 5, pp. 1137-1158. http://dx.doi.org/10.1046/j.1095-8649.2003.00108.x. http://dx.doi.org/10.1046/j.1095-8649.20...
). It is indicative of the preferred position in the water column (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
5. |
Relative length of the head |
RLH = HL/SL |
Directly related to the size of the prey, high values suggest species which are predators of relatively large prey (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
6. |
Relative length of the caudal peduncle |
RLCP = CPL/SL |
Relatively long peduncles indicate fish that inhabit turbulent waters and have good swimming skills (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.; Watson and Balon, 1984Watson, D.J. and Balon, E., 1984. Ecomorphological analysis of taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, vol. 25, no. 3, pp. 371-384. http://dx.doi.org/10.1111/j.1095-8649.1984.tb04885.x. http://dx.doi.org/10.1111/j.1095-8649.19...
). |
7. |
Compression Index of the caudal peduncle |
CICP= CPH/CPW |
It is inversely related to the amplitude of the swimming movements, higher values indicate compressed peduncles, typical of less active swimmers (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
8. |
Relative area of the caudal fin |
RACdF = CdFA/BA |
High values indicate fins capable of producing rapid pulses, typical for swimming of many benthic fish (Watson and Balon, 1984Watson, D.J. and Balon, E., 1984. Ecomorphological analysis of taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, vol. 25, no. 3, pp. 371-384. http://dx.doi.org/10.1111/j.1095-8649.1984.tb04885.x. http://dx.doi.org/10.1111/j.1095-8649.19...
); |
9. |
Aspect ratio of the caudal fin |
ARCdF = CdFW/CdFA |
Directly proportional to the amount of swimming that the fish conducts (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
10. |
Relative area of the pelvic fin |
RAPlF = PlFA/BA |
Benthic fish have relatively large areas (Gatz Junior, 1979Gatz JUNIOR, A.J., 1979. Ecological morphology of freshwater stream fishes. Tulanne Studies in Zoology Botany, vol. 21, pp. 91-124.). |
11. |
Relative area of the pectoral fin |
RAPtF = PtFA/BA |
Higher values indicate slower swimmers who use these fins to perform maneuvers. However, fish inhabitants of fast water that use them as water deflection surfaces, keeping their body close to the substrate, also have high values (Watson and Balon, 1984Watson, D.J. and Balon, E., 1984. Ecomorphological analysis of taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, vol. 25, no. 3, pp. 371-384. http://dx.doi.org/10.1111/j.1095-8649.1984.tb04885.x. http://dx.doi.org/10.1111/j.1095-8649.19...
). |
12. |
Aspect ratio of the pectoral fin |
ARPtF = PtFL/PtFW |
High values indicate long fins and suggest fish with great swimming ability (Watson and Balon, 1984Watson, D.J. and Balon, E., 1984. Ecomorphological analysis of taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, vol. 25, no. 3, pp. 371-384. http://dx.doi.org/10.1111/j.1095-8649.1984.tb04885.x. http://dx.doi.org/10.1111/j.1095-8649.19...
). |