Feeding Behaviour and Dental Morphology of Algae Scraping Cichlids (Pisces: Teleostei) in Lake Tanganyika

Abstract

Feeding behaviour in the natural situation and dental morphology of 13 Tanganyika species belonging to 6 genera of algae scraping cichlids were studied to understand the degree of specialization for algae feeding in relation to size. Three parameters, speed of grazing (SG), successive repeated times (SRT) and time interval of browsing (TIB), were measured to analyze the behaviour. The fist two parameters were applied to 6 species of Petrochromis, grazers and the third one to 7 other browsing species. Among grazers, Petrochromis polyodon is regarded as the most adapted and P. fasciolatus as the least adapted to grazing diatoms off the filamentous algae. Among browsers, Telmatochromis temporalis has distinctive behavioural and morphological features, showing the lowest degree of adaptation. The other 6 browsing species share similar features. Limnotilapia dardennei and Simochromis diagramma show a lower degree of adaptation. Tropheus moorei can be regarded as the best adapted to browsing filamentous algae by shearing. S. babaulti and S. marginatus are situated between each of them. Pseudosimochromis curvifrons seems to diverge into browsing by cutting, not shearing. TIB can be regarded as a handling time. The validity of the "jacks-of-all-trades" hypothesis is discussed.