Abstract
The pelagic larval phase represents a major opportunity for dispersal in benthic organisms, yet behaviors controlling and potentially limiting dispersal are still largely unknown for most larvae. Here, we present a new means of observing the orientation of larvae of all developmental stages in the pelagic environment. A cylindrical frame holding a semi‐open arena in which larvae are filmed is set to drift at a controlled depth within the natural environment. Larval trajectories are extracted from video data and used to quantify orientation behavior. Field tests with late‐stage coral reef fish larvae show that orientation can be detected from individual larval positions in the arena and can be significantly differentiated from random movement or artifactual behavior.
