Humboldt-Universität zu Berlin - Behavioural Physiology

Lisa Schilha, M. Sc.

The routine metabolic rate of Neotropical weakly electric fishes was found to be lower than the metabolic rates of other teleost fishes from similar, but temperate, habitats (Julian et al., 2003). This seems surprising considering that electric organ discharges (EODs) are generated on the basis of action potentials, which are known to be energetically quite costly. Taking into account that some species evolved continuous sinusoidal wave-type signals, supported by continuous, high-frequency action potential activity, this appears even more striking.

Crampton (1998) found that wave-type species are more likely to be found in fast-flowing rivers with high oxygen availability, whereas pulse-type species are more prevalent in stagnant waters with low oxygen availability. This hints to a higher energy demand of wave-type signals.

I try to shed some more light upon this subject by examining the metabolic costs of electric signalling in gymnotiform weakly electric fish. I use respirometry and histological approaches to solve this task. By comparing different species that use different types of signals, and testing several different water parameters (e.g., oxygen concentration, temperature), I hope to be able to determine links between electric signal type (wave-type or pulse-type), habitat preference, and life style.