Meeting Abstract

26-2  Thursday, Jan. 5 14:00 - 14:15  Biomechanical properties of a predator induced body armor in the freshwater crustacean Daphnia KRUPPERT, S*; HORSTMANN, M; WEISS, LC; WITZEL, U; SCHABER, CF; GORB, SN; TOLLRIAN, R; Ruhr-University Bochum, Germany; Ruhr-University Bochum, Germany; Ruhr-University Bochum, Germany; Ruhr-University Bochum, Germany; University of Kiel, Germany; University of Kiel, Germany; Ruhr-University Bochum, Germany sebastian.kruppert@rub.de

The freshwater crustacean Daphnia is known for its ability to develop inducible morphological defenses thwarting predators. These defenses are realized in form of morphological shape alterations e.g. “neckteeth” in D. pulex and “crests” in D. longicephala. Additionally, D. pulex was found to develop a sort of body armor, as its bivalved carapace surrounding the body, increases in overall stiffness. We tested whether D. longicephala also develops such a body armor, and investigated the structural features explaining increased stiffness in both species. Using electron microscopy, we found that the carapace architecture becomes highly laminated in both species exposed to predators. Using bio-indentation measurements, we found that this highly laminated structure results in the increase in stiffness (e-modulus). Likewise, we tested whether the overall adaptive morphology results in an increase in geometric stiffness i.e. the extent to which a geometric body resists deformation in response to an applied force. Subsequently, we conducted finite-element analysis considering e-modules as well as carapace architecture and shape alterations to determine whether both factor act synergistically to increase stiffness. We found that increased geometric stiffness is based on the highly laminated carapace. Furthermore, our results revealed species specific structure alterations indicating different, predator specific strategies to realize stiffness increase.