Anti-predator adaptations in a great scallop (Pecten maximus) – a palaeontological perspective

Abstract

Shelly fauna was exposed to increased pressure exerted by shell-crushing durophagous predators during the so-called Mesozoic Marine Revolution that was initiated in the Triassic. As a result of evolutionary ‘arms race’, prey animals such as bivalves, developed many adaptations to reduce predation pressure (e.g. they changed lifestyle and shell morphology in order to increase their mechanical strength). For instance, it was suggested that Pectinidae had acquired the ability to actively swim to avoid predator attack during the early Mesozoic. However, pectinids are also know to have a specific shell microstructure that may effectively protect them against predators. For instance, we highlight that the shells of some recent pectinid species (e.g. Pecten maximus) that display cross-lamellar structures in the middle part playing a significant role in the energy dissipation, improve the mechanical strength. In contrast, the outer layers of these bivalves are highly porous, which allow them to swim more efficiently by reducing the shell weight. Pectinids are thus perfect examples of animals optimising their skeletons for several functions. We suggest that such an optimisation of their skeletons for multiple functions likely occurred as a results of increased predation pressure during the so-called Mesozoic Marine Revolution.

Effects of hypoxia and non-lethal shell damage on shell mechanical and geochemical properties of a calcifying polychaete

“…6), which could also strengthen the shell. Such inducible defence response is commonly exhibited by calcifying organisms because shell repair should be prioritized to restore and enhance protection (Cheung et al, 2004;Hirsch et al, 2014;Brom et al, 2015). However, trade-offs are involved to activate the defence response, such as reduction in the less essential biological processes or activities (Trussell and Nicklin, 2002;Hoverman and Relyea, 2009;Babarro et al, 2016).…”

Morphological diversity of microstructures occurring in selected recent bivalve shells and their ecological implications

“…in Pecten maximus (Linnaeus, 1758). Scallops belong to the socalled free lying bivalve molluscs, therefore, they are the most exposed for potential attack (Harper and Skelton 1993;Piechocki 2009;Brom et al 2016). The bivalve M. edulis represent epifaunal mode of life.…”

Changing mineralogical properties of shells may help minimize the impact of hypoxia-induced metabolic depression on calcification

“…following non-lethal shell damage), harder and stiffer shells were 185 produced at a higher rate, despite the reduced energy intake by feeding. This is a typical anti-predator response since shell repair should be prioritized to restore and enhance protection (Cheung et al, 2004;Hirsch et al, 2013;Brom et al, 2015). This response can be achieved by downregulating the less essential physiological processes or activities as trade-offs (Rundle and Brönmark, 2001;Trussell and Nicklin, 2002;Hoverman and Relyea, 2009;Babarro et al, 2016).…”

“…Given the immobility of H. diramphus, the only effective anti-predator response is producing harder shells at a higher rate. In addition to a possible increase in the production of matrix proteins, the greater shell strength may be due to the formation of microstructures in the shell (Meyers et al, 2008;Brom et al, 2015), which warrants further 195 investigation.…”