Structure and mechanical properties of selected protective systems in marine organisms

Marine organisms have developed a wide variety of protective strategies to thrive in their native environments. These biological materials, although formed from simple biopolymer and biomineral constituents, take on many intricate and effective designs. The specific environmental conditions that shape all marine organisms have helped modify these materials into their current forms: complete hydration, and variation in hydrostatic pressure, temperature, salinity, as well as motion from currents and swells. These conditions vary throughout the ocean, being more consistent in the pelagic and deep benthic zones while experiencing more variability in the nearshore and shallows (e.g. intertidal zones, shallow bays and lagoons, salt marshes and mangrove forests). Of note, many marine organisms are capable of migrating between these zones. In this review, the basic building blocks of these structural biological materials and a variety of protective strategies in marine organisms are discussed with a focus on their structure and mechanical properties. Finally, the bioinspired potential of these biological materials is discussed.