Cool your jets: biological jet propulsion in marine invertebrates.

Brad J Gemmell,John H Costello,Sean P Colin,Kelly R Sutherland,James P Townsend,John O Dabiri

doi:10.1242/jeb.222083

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.

Highlights

Animal locomotion and the impact of the fluid environment on the evolution of body forms in swimming animals has long been a focus of evolutionary and functional biologists (e.g. Thompson, 1961; Vogel, 2013) and, more recently, to those within the field of engineering who work on ‘bio-inspired’ designs and focus on marine invertebrate animals (e.g. Villanueva et al, 2011; Gu and Guo, 2017; Tang et al, 2020). The focus of this Review, is a common swimming mode employed by a number of distantly related marine taxa (Fig. 1)
Many of these animals have relatively simple shapes and swim using few propulsive structures for locomotion. This has allowed for basic theoretical models of both propulsive and resistive forces to be developed
B.J.G., 0000-0001-9031-6591; J.H.C., 0000-0002-6967-3145; J.P.T., 00000002-4782-6083; K.R.S., 0000-0001-6832-6515 fluid patterns, which make the analyses of resistive forces, such as drag, more difficult (Daniel, 1983)

Summary

Introduction

Animal locomotion and the impact of the fluid environment on the evolution of body forms in swimming animals has long been a focus of evolutionary and functional biologists (e.g. Thompson, 1961; Vogel, 2013) and, more recently, to those within the field of engineering who work on ‘bio-inspired’ designs and focus on marine invertebrate animals (e.g. Villanueva et al, 2011; Gu and Guo, 2017; Tang et al, 2020). The focus of this Review, is a common swimming mode employed by a number of distantly related marine taxa (Fig. 1). Many of these animals have relatively simple shapes and swim using few propulsive structures (i.e. control surfaces; see Glossary) for locomotion. The primary objective of this Review is to summarize the current state of the literature for the major taxonomic groups of jetpropelled swimmers and identify similarities and differences between these groups By providing this information along with a historical context of experimental and modeling approaches, we aim to better facilitate comparative analyses to aid our understanding of the principles of aquatic jet propulsion

Objectives

Findings

Conclusion