Thermoregulation in the semi-aquatic yellow anaconda, Eunectes notaeus

1.Various factors affect a reptile's capacity for thermoregulation and most studies have focussed on terrestrial species.2.We investigated the thermoregulatory abilities of the yellow anaconda (Eunectes notaeus) in terms of selected body temperature (Tsel), set-point range (Tset) and body posture in terrestrial and aquatic thermal mosaics.3.Yellow anacondas selected higher body temperatures (Tb) and have a narrower Tset in a terrestrial environment than in an aquatic one.4.Coiled body postures were most frequently observed and were generally associated with higher Tb.