1. Compression index CI = MBH/MBW |
MBH - maximum body height MBW - maximum body width |
Higher values indicate lateral compression of the fish, expected for fish that exploit habitats with slower water velocity (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). |
2. Depression index DI = BMH/MBH |
BMH - body midline height MBH - maximum body height |
Lower values indicate species with depressed bodies, expected for fish that exploit habitats with rapid water velocity (Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.; Oliveira, 2005) |
3. Relative length of the caudal peduncle RLPd = CPdL/SL |
CPdL - caudal peduncle length SL - standard length |
Long caudal peduncle is associated with fish living in places with rapid water flow, owing the need for propulsion at short distances (Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.; Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
4. Relative height of the caudal peduncle RHPd = CPdH/MBH |
CPdH - caudal peduncle height MBH - maximum body height |
Lower values indicate greater maneuverability potential (Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
5. Relative width of the caudal peduncle RWPd = CPdW/MBW |
CPdW - caudal peduncle width MBW - maximum body width |
Higher relative values indicate better continuous swimmers (Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
6. Relative area of the dorsal fin RAD = DA/(SL)2
|
DA - dorsal fin area SL - standard length |
Species with dorsal fins with larger relative areas have better capacity to stabilization and braking in acceleration (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.). |
7. Relative area of the caudal fin RAC = CA/(SL)2
|
CA - caudal fin area SL - standard length |
Caudal fins with larger relative areas are important for acceleration (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.; Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
8. Aspect ratio of the caudal fin ARC = (CH)2/CA |
CH - caudal fin height CA - caudal fin area |
Higher values indicate fish with caudal fins with tendency to bifurcation, and generally are good swimmers for continuous swimming. Species with low values have caudal fins with larger areas and exhibit excellent performance for acceleration. (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.). |
9. Relative area of the anal fin RAA = AA/(SL)2
|
AA - anal fin area SL - standard length |
Larger relative area indicates higher maneuverability capacity and movement stabilization (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.). |
10. Aspect ratio of the anal fin ARA = (AL)2/AA |
AL - anal fin length AA - anal fin area |
Anal fins with larger aspect ratio indicate a higher capacity to make rapid progression and regression movements (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.). |
11. Relative area of the pectoral fin RAPt = PtA/(SL)2
|
PtA - pectoral fin area SL - standard length |
Larger areas can be directly associated with braking and acceleration (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). |
12. Aspect ratio of the pectoral fin ARPt = (PtL)2/PtA |
PtL - pectoral fin length PtA - pectoral fin area |
Higher values represent long and narrow fins. The highest values are associated with increased swimming speed (Breda et al., 2005Breda, L., E. F. Oliveira & E. Goulart. 2005. Ecomorfologia de locomoção de peixes com enfoque para espécies neotropicais. Acta Scientiarum. Biological Sciences, 27: 371-381.). |
13. Aspect ratio of the pelvic fin ARPv = (PvL)2/PvA |
PvL - pelvic fin length PvA - pelvic fin area |
High values denote long fins and are associated with braking (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.). |
14. Relative length of the head RLHd = HdL/SL |
HdL - head length SL - standard length |
Higher values are found in fish that feed on large prey (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). |
15. Relative height of the head RHHd = HdH/MBH |
HdH - head height MBH - maximum body height |
Higher values are found in fish that feed on relatively large prey. (Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
16. Relative width of the head RWHd = HdW/MBW |
HdW - head width MBW - maximum body width |
Higher values are found in fish that feed on relatively large prey (Oliveira et al., 2010Oliveira, E. F., E. Goulart, L. Breda, C. V. Minte-Vera, L. R. S. Paiva & M. R. Vismara. 2010. Ecomorphological patterns of the fish assemblage in a tropical floodplain: effects of trophic, spatial and phylogenetic structures. Neotropical Ichthyology, 8: 569-586.). |
17. Relative height of the mouth RHM = MH/MBH |
MH - mouth height MBH - maximum body height |
Higher values are found in fish that feed on relatively large prey (Gatz Jr., 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). Lower values are associated with greater suction capacity (Norton & Brainerd, 1993Norton, S. F. & E. L. Brainerd. 1993. Convergence in the feeding mechanics of ecomorphologically similar species in the Centrarchidae and Cichlidae. Journal of Experimental Biology, 176: 11-29.). |
18. Relative width of the mouth RWM = MW/MBW |
MW - mouth width MBW - maximum body width |
Higher values are found in fish that feed on relatively large prey (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). Lower values are associated with greater suction capacity (Norton & Brainerd, 1993Norton, S. F. & E. L. Brainerd. 1993. Convergence in the feeding mechanics of ecomorphologically similar species in the Centrarchidae and Cichlidae. Journal of Experimental Biology, 176: 11-29.). |
19. Eye position EP = EH/HdH |
EH - eye height HdH - head height |
Index related to the foraging position in the water column. Higher values represent species with dorsal eyes (Gatz, 1979Gatz, A. J. 1979. Ecological morphology of freshwater stream fishes. Tulane Studies in Zoology and Botany, 21: 91-124.; Watson & Balon, 1984Watson, D. J. & E. K. Balon. 1984. Ecomorphological analysis of fish taxocenes in rainforest streams of northern Borneo. Journal of Fish Biology, 25: 371-384.). |
20. Relative area of the eye RAE = EA/(SL)2
|
EA - eye area SL - standard length |
Index directly associated with visual capacity and food detection in the water column. Higher values indicate species with greater visual acuity (Pankhurst, 1989Pankhurst, N. W. 1989. The relationship of ocular morphology to feeding modes and activity periods in shallow marine teleosts from New Zealand. Environmental Biology of Fishes, 26: 201-211.). |
21. Protrusion index PI = LSO/LSC |
LSO - length of snout with the mouth open LSC - length of snout with the mouth closed |
Higher values related to the ability to capture evasive and large prey (Hulsey & García de León, 2005Hulsey, C. D. & F. J. García de León. 2005. Cichlid jaw mechanics: linking morphology to feeding specialization. Functional Ecology, 19: 487-494.; Cochran-Biederman & Winemiller, 2010Cochran-Biederman, J. L. & K. O. Winemiller. 2010. Relationships among habitat, ecomorphology and diets of cichlids in the Bladen River, Belize. Environmental Biology of Fishes, 88: 143-152.). |