Cool your jets: biological jet propulsion in marine invertebrates

Abstract

Pulsatile jet propulsion is a common swimming mode used by a diverse array of aquatic taxa from chordates to cnidarians. This mode of locomotion has interested both biologists and engineers for over a century. A central issue to understanding the important features of jet-propelling animals is to determine how the animal interacts with the surrounding fluid. Much of our knowledge of aquatic jet propulsion has come from simple theoretical approximations of both propulsive and resistive forces. Although these models and basic kinematic measurements have contributed greatly, they alone cannot provide the detailed information needed for a comprehensive, mechanistic overview of how jet propulsion functions across multiple taxa, size scales and through development. However, more recently, novel experimental tools such as high-speed 2D and 3D particle image velocimetry have permitted detailed quantification of the fluid dynamics of aquatic jet propulsion. Here, we provide a comparative analysis of a variety of parameters such as efficiency, kinematics and jet parameters, and review how they can aid our understanding of the principles of aquatic jet propulsion. Research on disparate taxa allows comparison of the similarities and differences between them and contributes to a more robust understanding of aquatic jet propulsion.

Distributed propulsion enables fast and efficient swimming modes in physonect siphonophores

“…There are few published estimates of efficiency and cost of transport for siphonophores, but our modeled cost of transport for an N. bijuga colony with two nectophores swimming asynchronously, 6.3 J kg −1 m −1 , was similar to the 3 J kg −1 m −1 calculated by Bone and Trueman ( 21 ) for the calycophoran siphonophore Abylopsis tetragona , which has one full-sized and one reduced nectophore. N. bijuga colonies with five or more nectophores were found to have costs of transport less than 3 J kg −1 m −1 when swimming asynchronously, putting them toward the lower end of reported values for jet-propelled swimmers ( 2 ).…”

“…Pulsed jets are an efficient, convergent solution to swimming propulsion for a broad taxonomic range of marine organisms, including cnidarians, cephalopods, and pelagic tunicates ( 1 , 2 ). Swimming through the use of multiple pulsed jets is much less common.…”

The hydrodynamics and kinematics of the appendicularian tail underpin peristaltic pumping

“…Their ability to filter and concentrate small, suspended particles comes from their unique hydrodynamic pumping strategy. Suggestions for bioinspired underwater vehicle and robotic design have focused on the kinematics and hydrodynamics of swimming in fish and invertebrates [13][14][15]55,[69][70][71]. The range of mechanisms that suspension feeding metazoans employ to separate particles from a fluid suspension is another fertile ground for biomimetic applications [28].…”

Metabolic trade-offs associated with homeostatic adjustments in pelagic and benthic cephalopods: Comparative evaluations of NH4+/H+ transport machinery in gills

“…This feature suggested that their different locomotion strategies, such as crawling or jetmotion, may correlate with their different metabolic strategies. Despite the fact that jet propulsion is not an efficient locomotion pattern that requires too much energy from aerobic respiration, this pattern is capable of rapid acceleration and locomotion (O'Dor and Webber, 1991;Gemmell et al, 2021). Octopuses, on the other hand, are considered to be jet-propulsion abandonment members (Wells, 1990;Huffard, 2006).…”