categories, while that of emaciated animals was significantly higher (0.24 ± 0.04·W·m·deg.-1 ) than all other categories. Blubber from sub-adults and pregnant females had the highest insulation values while fetuses and emaciated animals had the lowest. In nutritionally dependant life history categories, changes in blubber's thermal insulation were characterized by stable blubber quality (i.e. conductivity) and increased blubber quantity (i.e. thickness). In nutritionally independent animals, blubber quantity remained stable while blubber quality varied. A final, unexpected observation was that heat flux measurements at the deep blubber surface were significantly higher than that at the superficial surface, a pattern not observed in control materials. This apparent ability to absorb heat, coupled with blubber's fatty acid composition, suggest that dolphin integument may function as a phase change material.

SUMMARYBottlenose dolphins (Tursiops truncatus) produce various communicative sounds that are important for social behavior, maintaining group cohesion and coordinating foraging. For example, whistle production increases during disturbances, such as separations of mother-calf pairs and vessel approaches. It is clear that acoustic communication is important to the survival of these marine mammals, yet the metabolic cost of producing whistles and other socials sounds and the energetic consequences of modifying these sounds in response to both natural and anthropogenic disturbance are unknown. We used flow-through respirometry to determine whether the metabolic cost of sound production could be quantified in two captive dolphins producing social sounds (whistles and squawks). On average, we found that metabolic rates measured during 2min periods of sound production were 1.2 times resting values. Up to 7min were required for metabolism to return to resting values following vocal periods. The total metabolic cost (over resting values) of the 2min vocal period plus the required recovery period (163.3 to 2995.9mlO 2 or 3279.6 to 60,166.7J) varied by individual as well as by mean duration of sounds produced within the vocal period. Observed variation in received cumulative sound energy levels of vocalizations was not related to total metabolic costs. Furthermore, our empirical findings did not agree with previous theoretical estimates of the metabolic cost of whistles. This study provides the first empirical data on the metabolic cost of sound production in dolphins, which can be used to estimate metabolic costs of vocal responses to environmental perturbations in wild dolphins.

SUMMARYElephant movement patterns in relation to surface water demonstrate that they are a water-dependent species. Thus, there has been interest in using surface water management to mitigate problems associated with localized elephant overabundance. However, the physiological mechanisms underlying the elephant's water dependence remain unclear. Although thermoregulation is likely an important driver, the relationship between thermoregulation, water use and climate has not been quantified. We measured skin surface temperature of and cutaneous water loss from 13 elephants (seven African, 3768±642kg; six Asian, 3834±498kg) and determined the contribution of evaporative cooling to their thermal and water budgets across a range of air temperatures (8-33°C). We also measured respiratory evaporative water loss and resting metabolic heat production on a subset of elephants (N=7). The rate of cutaneous evaporative water loss ranged between 0.31 and 8.9gmin m −2 for African elephants. Simulated thermal and water budgets using climate data from Port Elizabeth, South Africa, and Okaukuejo, Namibia, suggested that the 24-h evaporative cooling water debt incurred in warm climates can be more than 4.5 times that incurred in mesic climates. This study confirms elephants are obligate evaporative coolers but suggests that classification of elephants as water dependent is insufficient given the importance of climate in determining the magnitude of this dependence. These data highlight the potential for a physiological modeling approach to predicting the utility of surface water management for specific populations. Supplementary material available online at

Many animals produce louder, longer or more repetitious vocalizations to compensate for increases in environmental noise. Biological costs of increased vocal effort in response to noise, including energetic costs, remain empirically undefined in many taxa, particularly in marine mammals that rely on sound for fundamental biological functions in increasingly noisy habitats. For this investigation, we tested the hypothesis that an increase in vocal effort would result in an energetic cost to the signaler by experimentally measuring oxygen consumption during rest and a 2 min vocal period in dolphins that were trained to vary vocal loudness across trials. Vocal effort was quantified as the total acoustic energy of sounds produced. Metabolic rates during the vocal period were, on average, 1.2 and 1.5 times resting metabolic rate (RMR) in dolphin A and B, respectively. As vocal effort increased, we found that there was a significant increase in metabolic rate over RMR during the 2 min following sound production in both dolphins, and in total oxygen consumption (metabolic cost of sound production plus recovery costs) in the dolphin that showed a wider range of vocal effort across trials. Increases in vocal effort, as a consequence of increases in vocal amplitude, repetition rate and/or duration, are consistent with behavioral responses to noise in free-ranging animals. Here, we empirically demonstrate for the first time in a marine mammal, that these vocal modifications can have an energetic impact at the individual level and, importantly, these data provide a mechanistic foundation for evaluating biological consequences of vocal modification in noise-polluted habitats.

Our short‐term longitudinal study explored undergraduate students' experiences with performing authentic science practices in the classroom in relation to their science achievement and course grades. In addition, classroom experiences (felt recognition as a scientist and perceived classroom climate) and changes over a 10‐week academic term in STEM (science, technology, engineering, and mathematics) identity and motivation were tested as mediators. The sample comprised 1,079 undergraduate students from introductory biology classrooms (65.4% women, 37.6% Asian, 30.2% White, 25.1% Latinx). Using structural equation modeling (SEM), our hypothesized model was confirmed while controlling for class size and GPA. Performing science practices (e.g., hypothesizing or explaining results) positively predicted students' felt recognition as a scientist; and felt recognition positively predicted perceived classroom climate. In turn, felt recognition and classroom climate predicted increases over time in students' STEM motivation (expectancy‐value beliefs), STEM identity, and STEM career aspirations. Finally, these factors predicted students' course grade. Both recognition as a scientist and positive classroom climate were more strongly related to outcomes among underrepresented minority (URM) students. Findings have implications for why large‐format courses that emphasize opportunities for students to learn science practices are related to positive STEM outcomes, as well as why they may prove especially helpful for URM students. Practical implications include the importance of recognition as a scientist from professors, teaching assistants, and classmates in addition to curriculum that engages students in the authentic practices of science.