Fig. 6

Animals’ propensity to gravitax (λ) as a function of animal vitality (Wo) (A) and the animal’s depth beneath the liquid surface (B). The reddish region (λ < 1) indicates the absence of gravitaxis and an orientational probability distribution (pdf) that is dissimilar to that of wild-type animals with a confidence level greater than 95%. The bluish region indicates competency to gravitax (λ > 1). The solid line in B corresponds to Eq. (2) for N2. The residence time of animals in LUDOX was converted to equivalent depth with the aid of the settling velocity