This course will attempt to bridge the gap between two worlds: biology and materials science, mainly from a mechanics viewpoint. It will address problems in mechanics that are relevant to structures encountered in nature. This will be achieved by using a language and a style that students from different faculties/backgrounds should find accessible and useful. Biologists and materials scientists increasingly address and investigate research fields of shared interest. However, identical terms in both communities often mean different things, and their experimental approaches to quantify a given concept or parameter are wholly different. Few understand the difference between, say, stiffness and Young's modulus, or between strength, hardness, toughness, robustness, resilience, etc. Few realize how vague the information indeed is when stating that a given material is 'more elastic' than another, for example. We will examine the difference between synthetic materials and biological structures, the mechanical behavior of families of materials encountered in nature, the structure and behavior of fibrous and layered structures in nature, basic models in the mechanics of fibers, bundles, composites. We will study the analysis of laminated composites, spiral/helical (Bouligand) structures in plants and animals, loops, elastica and buckling in biology. Other topics will include fracture and toughness, protein elasticity and strength, a-helices and b-sheets, platelet-reinforced composites, staggered structures, mineralized collagen, bone, dentine, laminated structures for compression and impact resistance in nature. If time permits we will look at specific design examples: how does a gecko stick to a wall, could the archaeopteryx fly? What is the source of toughness of nacre? Why are elastic constants crucial for hearing? Why is the mechanics of virus membranes important?