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Climate change will increase the frequency and intensity of extreme climatic events (e.g. storms) that result in repeated pulses of hyposalinity in nearshore ecosystems. Sea urchins inhabit these ecosystems and are stenohaline (restricted to salinity levels ∼32‰), thus are particularly susceptible to hyposalinity events. As key benthic omnivores, sea urchins use hydrostatic adhesive tube feet for numerous functions, including attachment to and locomotion on the substratum as they graze for food. Hyposalinity severely impacts sea urchin locomotor and adhesive performance but several ecologically relevant and climate change-related questions remain. First, do sea urchin locomotion and adhesion acclimate to repeated pulses of hyposalinity? Second, how do tube feet respond to tensile forces during single and repeated hyposalinity events? Third, do the negative effects of hyposalinity exposure persist following a return to normal salinity levels? To answer these questions, we repeatedly exposed green sea urchins (Strongylocentrotus droebachiensis) to pulses of three different salinities (control: 32‰, moderate hyposalinity: 22‰, severe hyposalinity: 16‰) over the course of two months and measured locomotor performance, adhesive performance, and tube foot tensile behavior. We also measured these parameters 20 h after sea urchins returned to normal salinity levels. We found no evidence that tube feet performance and properties acclimate to repeated pulses of hyposalinity, at least over the timescale examined in this study. In contrast, hyposalinity has severe consequences on locomotion, adhesion, and tube foot tensile behavior, and these impacts are not limited to the hyposalinity exposure. Our results suggest both moderate and severe hyposalinity events have the potential to increase sea urchin dislodgment and reduce movement, which may impact sea urchin distribution and their role in marine communities. [ABSTRACT FROM AUTHOR]

Everyone has problems, from the smallest ant competing for a food source to the largest elephant needing to cool down. Fortunately, organisms have structures that function to help them solve these problems. So when a group of fourth-grade students look for solutions to their problems, who do they turn to? A biological champion, of course! Plants and animals have a long history of solving problems, and by imitating their strengths, students can generate ideas for a better future. Currently, teachers are looking beyond the basic elements of core ideas to incorporate engineering practices; however, making this connection can be a challenge. The authors felt that by incorporating biomimicry, the practice of using nature as a guide to solve human problems (Baumeister 2014), into the existing "Next Generation Science Standards" ("NGSS") fourth-grade science unit on structure and function, they could meet this challenge. Students ultimately explore the question: "What can we learn from plants and animals to help solve the problems we face in our lives?" Then, by working through the engineering design process, they created a model that demonstrates a solution to their problem!

Geckos are remarkable in their ability to reversibly adhere to smooth vertical, and even inverted surfaces. However, unraveling the precise mechanisms by which geckos do this has been a long process, involving various approaches over the last two centuries. Our understanding of the principles by which gecko adhesion operates has advanced rapidly over the past 20 years and, with this knowledge, material scientists have attempted to mimic the system to create artificial adhesives. From a biological perspective, recent studies have examined the diversity in morphology, performance, and real-world use of the adhesive apparatus. However, the lack of multidisciplinarity is likely a key roadblock to gaining new insights. Our goals in this paper are to 1) present a historical review of gecko adhesion research, 2) discuss the mechanisms and morphology of the adhesive apparatus, 3) discuss the origin and performance of the system in real-world contexts, 4) discuss advancement in bio-inspired design, and 5) present grand challenges in gecko adhesion research. To continue to improve our understanding, and to more effectively employ the principles of gecko adhesion for human applications, greater intensity and scope of interdisciplinary research are necessary. [ABSTRACT FROM AUTHOR]

The surface temperature of tree branches in the tropical rainforest canopy can reach up to 55°C. Ants and other small cursorial organisms must maintain adequate attachment in this extreme microenvironment to forage effectively and avoid falling. Ant adhesion depends on liquid secretions that should become less viscous at high temperatures, causing ants to slip. However, tropical arboreal ants have high thermal tolerance and actively forage on hot canopy surfaces, suggesting that these ants can maintain adhesion on hot substrates. We measured tarsal pad shear adhesion of 580 workers (representing 11 species and four subfamilies) of tropical arboreal ants at temperatures spanning the range observed in the field (23-55°C). Adhesive performance among species showed three general trends: (1) a linear decrease with increasing temperature, (2) a non-linear relationship with peak adhesive performance at ca. 30-40°C, and (3) no relationship with temperature. The mechanism responsible for these large interspecific differences remains to be determined, but likely reflects variation in the composition of the secreted adhesive fluid. Understanding such differences will reveal the diverse ways that ants cope with highly variable, and often unpredictable, thermal conditions in the forest canopy., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

While many gecko-inspired hierarchically structured surfaces perform as well as or better than the natural adhesive system, these designs often fail to function across a variety of contexts. For example, the gecko can adhere to rough, wet and dirty surfaces; however, most synthetic mimics cannot maintain function when faced with a similar situation. The solution to this problem lies in a more thorough investigation of the natural system. Here, we review the adhesive system of the gecko toe pad, as well as the far less-well-studied anti-adhesive system that results from the chemistry and structure of the toe pad (superhydrophobicity). This paradoxical relationship serves as motivation to study functional optimization at the system level. As an example, we experimentally investigate the role of surface lipids in adhesion and anti-adhesion, and find a clear performance trade-off related to shear adhesion in air on a hydrophilic surface. This represents the first direct investigation of the role of surface lipids in gecko adhesion and anti-adhesion, and supports the argument that a system-level approach is necessary to elucidate optimization in biological systems. Without such an approach, bioinspired designs will be limited in functionality and context, especially compared to the natural systems they mimic.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'., (© 2016 The Author(s).)