The Cichlid Fishes of Lake Malawi, Africa

Abstract of Doctoral Dissertation

Elisabeth A. Hale
The Pennsylvania State University, 1997
Adviser: Jay R. Stauffer, Jr.  

An investigation of the utility of feeding angles among Lake Malawi rock-dwelling cichlids (Teleostei: Cichlidae)  

Feeding angle differences among Labeotropheus trewavasae Fryer, Labeotropheus fuelleborni Ahl, Melanochromis auratus (Boulenger), Petrotilapia spp., Pseudotropheus elongatus Fryer, Pseudotropheus tropheops Regan, Pseudotropheus zebra (Boulenger), and Pseudotropheus gracilior (Trewavas) were examined. Image analyses were used to measure feeding angles of the fishes videotaped in Lake Malawi. The median feeding angles ranged from 35 degrees to 91 degrees. There are four feeding angle groups among the eight rock-dwelling species that were examined: (1) L. trewavasae (35°), (2) L. fuelleborni, M. auratus, and P. elongatus (44-48°), (3) P. tropheops (53°), and (4) Petrotilapia spp., P. gracilior and P. zebra (86-91°). Labeotropheus trewavasae, M. auratus and P. zebra are three Lake Malawi rock-dwelling cichlids, with significantly different feeding angles. To determine whether different feeding angles allow for differential access to food, L. trewavasae, M. auratus and P. zebra were observed feeding in the laboratory on artificial substrates. Feeding angles measured in the laboratory were congruent with field data and no significant (p > 0.05) effect of feeding angle was attributed to the tank chambers. No significant (p > 0.05) differences in the extent or distribution of food acquisition were observed, however differences in the first bite were evident.




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