Spatial learning based on visual landmarks in the freshwater blenny Salaria fluviatilis (Asso, 1801)

The use and learning of visual landmarks seem to be strongly influenced by ecological demands and vary according to habitat, sex and, presumably, dominance status. In blennies, sexes differ in their home-range extension and this could predispose them to use different mechanisms to navigate. The main aim of this study was to investigate if Salaria fluviatilis (a benthonic and polyginic freshwater blenny) was able to solve a learning maze using direct visual landmarks. Performance between sexes was compared, and the possible relationship between the males' secondary sexual characteristics (SSCs) development and their spatial ability was considered. In this species, the SSCs consist of a cephalic crest and a pair of anal glands. Fish were subjected to 10 sessions (each one consisting of 11 consecutive trials) in a specially designed apparatus where they had to find the correct exit using direct visual landmarks. The proportion of males that learned the task (80%) was higher than that of females (30%). Cephalic crest development of the male was associated with a higher readiness to solve the spatial task. These results support the importance of ecological demands in shaping a species' spatial abilities. They also provide a comprehensive perspective that would link dominance (through cephalic crest development), learning and sexual selection.