Metachronal Rowing by a Peacock Mantis Shrimp

Metachronal rowing is a widely used swimming technique employed by animals which have multiple pairs of swimming legs such as shrimp and krill. In this locomotion technique, appendages are sequentially stroked in a back-to-front wave moving along the animal’s body, a pattern that is thought to increase swimming efficiency in comparison to front-to-back or synchronous stroke patterns. The fluid dynamics of metachronal rowing is not well understood. Experiments suggest that under some circumstances the flow pulses generated by each appendage may synergistically join together to form a coherent propulsive jet while in others the pulses remain separate, with unknown consequences for propulsive efficiency. Further, the swimming ability of mantis shrimp is not well investigated. Here we present time-resolved pleopod kinematics and planar particle image velocimetry measurements of the flow generated by a swimming peacock mantis shrimp (Odontodactylus scyllarus) with body and pleopod lengths of 114 mm and 15 mm, respectively. Illumination is provided by a near infrared laser. The flow generated by the metachronally stroking pleopods is captured in both hovering and fast forward swimming modes to examine the effect of varying advance ratio on the mantis shrimp’s flow signature.