Rheological Properties and Drag Reduction Performance of Puffer Epidermal Mucus

Abstract

Most species of fish are covered with mucus, which provides the effect of reduction in swimming drag. In this paper, three concentrations of puffer epidermal mucus were obtained from the epidermal mucosa of puffer. The rheological properties and the drag reduction performance of the puffer epidermal mucus were characterized via a rheometer experimental and numerical simulation method. The relationship between the rheological properties and the drag reduction performance was analyzed and discussed, and the drag reduction mechanism of the puffer epidermal mucus was further explored. The results showed that the best drag reduction rate was 6.2% when the inflow velocity and concentration of puffer epidermal mucus were 0.1 m/s and 18.2 g/L, respectively. The rheological properties of puffer epidermal mucus are viscoelastic, and the mucus forms a sliding surface, which reduces the frictional drag of the fluid. In conclusion, this paper may provide a reference for the development of drag-reducing agents and drag-reducing research studies on other fish mucus.

A novel gnotobiotic experimental system for Atlantic salmon (Salmo salar L.) reveals a microbial influence on mucosal barrier function and adipose tissue accumulation during the yolk sac stage

“…Whereas our derivation procedure used a longer contact time than at hatcheries our results may suggest that current practices in aquaculture disrupt the mucosal barrier in yolk sac fry during this vulnerable developmental stage. Maintenance of the mucus layer is critical for fishes because of its multiple functions ( Reverter et al., 2018 ; Cabillon and Lazado, 2019 ) in behavior ( Grutter et al., 2011 ; Satoh and Sowersby, 2021 ), immunity and barrier function ( Benhamed et al., 2014 ; Salinas, 2015 ; Brinchmann, 2016 ; Tiralongo et al., 2020 ), locomotion ( Zhang et al., 2022b ), gas and osmotic exchange ( Wright, 2021 ), amongst others. Moreover, an intact mucus layer is key for a teleost gnotobiotic model, as it is a niche for bacterial colonization ( Weber et al., 2010 ; Gomez et al., 2013 ; Carda-Diéguez et al., 2017 ; Reinhart et al., 2019 ).…”

Aerial and aquatic biological and bioinspired flow control strategies

“…However, drag is still reduced due to the newly uncovered tips of their spines that texture the surface of the fish. Thus, the mechanism changes from reducing skin-friction drag via a slip layer to reducing pressure drag via the textured surface 153 . The mucus layer as an engineering flow control strategy is problematic due to the gradual degradation of the layer in the presence of an external flow 156 .…”

Superslippery Long‐Chain Entangled Polydimethylsiloxane Gel with Sustainable Self‐Replenishment

“…For example, an insectivorous plant Nepenthes has a nectar layer that works as a lubricant, and thus insects sitting on the surface slide into the pitcher and are digested by the plant. [ 1 ] In addition, marine organisms, such as seaweed, [ 2 ] coral reefs, [ 3 ] puffer fish, [ 4 ] hagfish, [ 5 ] and eels, [ 6 ] secrete mucus from their mucous membrane to reduce frictional drag and prevent surface contamination in harsh underwater environments. [ 7 ] Inspired by these lubricating functions of natural organisms, various biomimetic slippery surfaces have been developed in many engineering fields, including antifouling, [ 8 ] drag reduction, [ 9 ] anti‐icing, [ 10 ] anticorrosion, [ 11 ] and self‐cleaning.…”