A comparative study of piscine defense: The scales of Arapaima gigas, Latimeria chalumnae and Atractosteus spatula.
We compare the characteristics of the armored scales of three large fish, namely the Arapaima gigas (arapaima), Latimeria chalumnae (coelacanth), and Atractosteus spatula (alligator gar), with specific focus on their unique structure-mechanical property relationships and their specialized ability to provide protection from predatory pressures, with the ultimate goal of providing bio-inspiration for manmade materials. The arapaima has flexible and overlapping cycloid scales which consist of a tough Bouligand-type arrangement of collagen layers in the base and a hard external mineralized surface, protecting it from piranha, a predator with extremely sharp teeth. The coelacanth has overlapping elasmoid scales that consist of adjacent Bouligand-type pairs, forming a double-twisted Bouligand-type structure. The collagenous layers are connected by collagen fibril struts which significantly contribute to the energy dissipation, so that the scales have the capability to defend from predators such as sharks. The alligator gar has inflexible articulating ganoid scales made of a hard and highly mineralized enamel-like outer surface and a tough dentine-like bony base, which resist powerful bite forces of self-predation and attack by alligators. The structural differences between the three scales correspond with the attack of their predators, and show refined mechanisms which may be imitated and incorporated into superior bioinspired and biomimetic designs that are specialized to resist specific modes of predation.
Department of Mechanical and Aerospace Engineering, Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093, USA.
Vincent R
VR
Sherman
Department of Mechanical and Aerospace Engineering, Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093, USA.
Haocheng
H
Quan
Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
Wen
W
Yang
Department of Materials Science and Engineering, University of California Berkeley, CA 94720, USA.
Robert O
RO
Ritchie
Department of Mechanical and Aerospace Engineering, Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093, USA; Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA. Electronic address: mameyers@ucsd.edu.
Marc A
MA
Meyers
D000075342:Animal Scales / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000648:ultrastructure; D005399:Fishes; D006244:Hardness; D011235:Predatory Behavior
D003094:Collagen
Alligator gar; Arapaima; Bioinspiration; Bouligand; Coelacanth; Scales