Weakly electric fish 2

Chirp structure and EOD frequency differs across wave-type fish and can be sexually dimorphic, though to different extents. In Apteronotids, EOD frequency - males often have lower EOD frequency than females - and chirping can be sexually dimorphic, but appears in a number of different ways (Smith 2013, 2422; Ho et al. 2013, 335; Ho et al. 2010, 1050). For example, A. albifrons males have lower EOD frequencies than females while A. leptorhynchus males have a higher EOD frequency than females (Smith 2013, 2422). Additionally, in A. leptorhynchus, males chirp more than females and in A. bonapartii and A. devenanzii chirp complexity is higher in males than in females (Smith 2013, 2428; Ho et al. 2010, 1059). However, another Apteronotid Sternarchogiton nattereri shows no sexual dimorphism, as males and females show no discernible difference in EOD frequency, chirp rate, and chirp form (Ho et al. 2013,337). Instead, S. nattereri shows differences in EOD frequency that are dependent on male morphology, with toothed males showing higher EOD frequency than toothless males (Fernandes et al. 2010, 660). In the wave-type Gymnotiform Gymnotus omarorum, and unlike in many of the aforementioned Apteronotids, electric signalling is sexually monomorphic (Batista et al. 2012, 398). Sexually monomorphic electrocommunicative behaviour has also been observed in other non-Apteronotid genera such Eigenmannia and Sternopygus (Smith 2013, 2422).