The Presence of a Substrate Strengthens The Jet Generated by Upside-Down Jellyfish

Abstract

Upside-down jellyfish, Cassiopea, are prevalent in warm and shallow parts of the oceans throughout the world. They are unique among jellyfish in that they rest upside down against the substrate and extend their oral arms upwards. This configuration allows them to continually pull water along the substrate, through their oral arms, and up into the water column for feeding, nutrient and gas exchange, and waste removal. Although the hydrodynamics of the pulsation of jellyfish bells has been studied in many contexts, it is not clear how the presence or absence of the substrate alters the bulk flow patterns generated by Cassiopea medusae. In this paper, we use three-dimensional (3D) particle tracking velocimetry and 3D immersed boundary simulations to characterize the flow generated by upside-down jellyfish. In both cases, the oral arms are removed, which allows us to isolate the effect of the substrate. The experimental results are used to validate numerical simulations, and the numerical simulations show that the presence of the substrate enhances the generation of vortices, which in turn augments the upward velocities of the resulting jets. Furthermore, the presence of the substrate creates a flow pattern where the water volume within the bell is ejected with each pulse cycle. These results suggest that the positioning of the upside-down jellyfish such that its bell is pressed against the ocean floor is beneficial for augmenting vertical flow and increasing the volume of water sampled during each pulse.

Light exposure induces phenotypic plasticity of the upside-down jellyfishCassiopeaand its endosymbiotic dinoflagellates

“…Our results do not support host-endosymbiont linked phenotypic relationships. While it's conceivable that photosystem regulation may be an auxiliary effect of pulsation, based on our research and previous research, pulsation most like primarily serves substrate attachment, and heterotrophy (Battista et al, 2022;Durieux et al, 2021;Hamlet and Miller, 2012;Santhanakrishnan et al, 2012), before photosynthetic regulation.…”

“…In addition to stinging cells lining their oral arms and digitate cirri, Cassiopea also release mucous-bound clusters of stinging cells called cassiosomes into the water column to immobilize prey (Ames et al, 2020), and then use bell pulsations to direct the prey into their mouths (Hamlet et al, 2011; Santhanakrishnan et al, 2012). Bell pulsation may also regulate the jellyfish microenvironment, incorporate endosymbionts, eliminate waste, and distribute gametes (Battista et al, 2022; Freeman et al, 2016; Hamlet et al, 2011; Hoover et al, 2021; Welsh et al, 2009). These processes make Cassiopea spp.…”

“…In the co-evolution of host-endosymbiont interactions, symbiotic populations within the host must be controlled in order to sustain the relationship (Rivera and Davies, 2021;Xiang et al, 2020). The behavioral plasticity of Cassiopea in response to environmental change has been proposed to help regulate the endosymbiotic assemblage (Battista et al, 2022;Freeman et al, 2016;Welsh et al, 2009), and the endosymbionts, directly affect the host's resilience (Kenkel and Bay, 2018;McQuagge et al, 2023;Roth, 2014). However, light is the direct signaling stimulus known to impact photosynthetic regulation of photo-endosymbionts (Goulet et al, 2005;Sorek et al, 2013;Xiang et al, 2015;Zaheri et al, 2019).…”

Design, Modeling, and Control of an Aurelia-Inspired Robot Based on SMA Artificial Muscles

“…The method chosen to approximate the thrust production of the jellyfish robot combines a theoretical model with experimental measurements. The theoretical model was based on techniques developed for jetting jellyfish by Daniel [ 39 , 40 , 41 ]. Daniel believes that during the contraction phase, water is forcibly ejected or injected from the subumbrellar cavity through the velar aperture to provide thrust, and the thrust acts in a direction opposite to the motion of the ejected fluid.…”

Correlative Light, Electron Microscopy and Raman Spectroscopy Workflow To Detect and Observe Microplastic Interactions with Whole Jellyfish

“…Their close proximity to land makes them interesting for study because they are potentially exposed to high initial concentrations of land-based MPs released into the marine environment. ,, This is particularly promising when considered in tandem with their reported ability to retain pollutants over the course of a few days to weeks, providing researchers with an opportunity to study short-term fluctuations in MP levels within a region. ,, These characteristics as well as others (e.g., the potential to stir up sedimented MPs due to their benthic nature, their ease of collection, and ease of cultivating in a laboratory) serve to support the idea that Cassiopea sp. jellyfish could function as bioindicator species for pollutants such as MPs. − …”