Behaviour and habitat of the Indian Ocean amphibious blenny, Alticus monochrus

Alticus monochrusBleeker is an amphibious blenny that inhabits exposed and moderately exposed rocky shores of Mauritius and other islands of the southwestern Indian Ocean. It remains above the water line on moist or wet substrata over which it migrates vertically and/or horizontally with the tide. Rapid terrestrial locomotion is accomplished by leaping during which the entire body leaves the substratum. When chased into water, it immediately re-emerges. A. monochrus feeds on emerged microscopic algae scraped from the rocks. An ethogram based primarily on field observations is presented. Although A. monochrus performs all feeding, reproductive and agonistic behaviours in air, and consequently is one of the most terrestrial intertidal fishes, its behaviour patterns are similar to those described for other intertidal blennies.