Structure–behaviour correlations between two genetically closely related snail species

Abstract

Species, through their structure and composition, have evolved to respond to environmental constraints. Predator-prey interactions are among environmental pressures that can lead to speciation, but it remains unclear how this pressure can be related to the material structure and performance. Recently, two land snails, Karaftohelix editha and Karaftohelix gainesi, were found to exhibit divergent phenotypes and responses to predation despite sharing the same habitat and most of their genome. Indeed, under attack from a beetle, K. editha snails retract into their shell whereas K. gainesi snails swing their shell. In this paper, we looked at the microstructure, composition, morphology and mechanics of the shells of those two species and discuss potential relationships between material structure and the snail defence behaviour. The results of this study provide additional arguments for the role of predator-prey interactions on speciation, as well as an unusual approach for the design of biomimetic structures adapted to a particular function.

Rediscovering the dancing semislug genus Cryptosemelus Collinge, 1902 (Eupulmonata, Ariophantidae) from Thailand with description of two new species

“…Predator-prey interactions are recognized as major processes promoting morphological and behavioral diversity (Vermeij 1987;Chiba 2007;Morii et al 2016;Sugiura 2016;Le Ferrand and Morii 2020). Land snails are preyed upon by a wide range of predators (e.g., rodents, birds, snakes, insects, and molluscs).…”

“…Land snails are preyed upon by a wide range of predators (e.g., rodents, birds, snakes, insects, and molluscs). Their own anti-predator adaptations, a passive defense by pulling their body into their shell and an active behavior by swinging their shell around, are well documented and are potentially associated with differences in shell traits (Vermeij 1987(Vermeij , 1993Chiba 2007;Baalbergen 2014;Liew and Schilthuizen 2014;Morii et al 2016;Morii and Wakabayashi 2017;Le Ferrand and Morii 2020). In contrast, the evolution of slug and semislug forms have sacrificed the protection offered by possession of a shell for the mobility, fast body movements, and ability to occupy very small spaces afforded by the reduction or elimination of the shell (Solem 1974;Barker 2001;Wiktor 2002;Dedov et al 2019).…”

Microstructure Analysis and Chemical and Mechanical Characterization of the Shells of Three Freshwater Snails

“…globosa (Figure E) where the larger lamellae inclined perpendicular to the outer lamellae in prisms. Changes in crystal orientation make the shell more resistant to fracture …”

“…Changes in crystal orientation make the shell more resistant to fracture. 98 The growth and structural peculiarities of the molluscan shells, particularly the bivalve and gastropod shells, have been studied to corroborate the evolutionary processes, 13,14 physical properties, and functional roles. 22,80,81,88 The elaboration of the microarchitecture, chemical composition, and mechanical properties 8,12,13,64,95 has been the foundation for promoting the molluscan shell as a biological material with multiple industrial, agricultural, and biomedical applications.…”

The habitat use and trophic niche comparisons among closely related land snails in Northeast Asia

“…Many species of Karaftohelix land snails pulled their soft body into their shell when they were attacked, which is similar to most other land snails (i.e., passive defense); however, there were two exceptions— K. gainesi in Hokkaido Is., northern Japan, and K. selskii in the Russian Far East—and these species swung their shells against predators and survived their attack (i.e., active defense; Morii et al, 2016). There were many structure–behavior correlations for each anti‐predator strategy in snails; passive defense species had, for instance, smaller shell size, smaller relative aperture size, larger number of whorls, thicker shell thickness and higher Young's modulus of the shell (harder shell) than that of passive defense species (Le Ferrand & Morii, 2020; Morii et al, 2016). Moreover, K. gainesi and K. selskii evolved independently from different lineages in northern Japan and south‐eastern Russia, respectively (Morii et al, 2016).…”