The red sweat of the hippopotamus

Saikawa, Yoshirou; Hashimoto, Kimiko; Nakata, Masaya; Yoshihara, Masato; Nagai, Kiyoshi; Ida, Motoyasu; Komiya, Teruyuki

doi:10.1038/429363a

Cited by 71 publications

(51 citation statements)

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“…The hippopotamus secretes a modified sweat-type substance from subdermal glands that functionally acts as sweat but which also provides sun protection and has antibacterial properties (Luck and Wright, 1964;Saikawa et al, 2004). In contrast, elephant integument is more permeable to water relative to other mammalian species (Dunkin, 2012).…”

Section: The Skin and Control Of Cewlmentioning

confidence: 99%

Climate influences thermal balance and water use in African and Asian elephants: physiology can predict drivers of elephant distribution

Dunkin

Wilson²,

Way³

et al. 2013

Journal of Experimental Biology

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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

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Section: The Skin and Control Of Cewlmentioning

confidence: 99%

Climate influences thermal balance and water use in African and Asian elephants: physiology can predict drivers of elephant distribution

Dunkin

Wilson²,

Way³

et al. 2013

Journal of Experimental Biology

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“…Does cosmetic coloration involve rare or common pigments, pigments obtained from the diet, modified pigments, or pigments synthesized de novo? Are these pigments functional (see e.g., Saikawa et al 2004) or purely ornamental? Does the composition of cosmetics change annually?…”

Section: Concluding Remarks and Suggestions For Future Researchmentioning

confidence: 99%

“…In some mammals, secretions from integumentary glands color the surrounding pelage, thereby acting as a visual signal, most notably among some marsupials and bats (Nicholls and Rienits 1971;Vevers 1964). Similarly, the hippopotamus (Hippopotamus amphibius) produces a striking "red sweat" that temporarily colors the animal red (Saikawa et al 2004). The authors proposed protection against UV light or bacteria as potential functions (Saikawa et al 2004), but they did not consider visual signaling.…”

Section: Concluding Remarks and Suggestions For Future Researchmentioning

confidence: 99%

“…Similarly, the hippopotamus (Hippopotamus amphibius) produces a striking "red sweat" that temporarily colors the animal red (Saikawa et al 2004). The authors proposed protection against UV light or bacteria as potential functions (Saikawa et al 2004), but they did not consider visual signaling. Cosmetics substances are extensively used by humans, mainly to alter the perception of attractiveness or to signal group identity (Grammer et al 2003).…”

Section: Concluding Remarks and Suggestions For Future Researchmentioning

confidence: 99%

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Cosmetic Coloration in Birds: Occurrence, Function, and Evolution

Delhey

Peters

Kempenaers

2007

The American Naturalist

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Colorful plumages are conspicuous social signals in birds, and the expression of these colors often reflects the quality of their bearers. Since mature feathers are dead structures, plumage color is often considered a static signal that does not change after molt. Feathers, however, can and do deteriorate between molts, and birds need to invest heavily in plumage maintenance. Here we argue that this need for preserving plumage condition and hence signaling content might have given rise to a novel type of sexual signal: cosmetic coloration. Cosmetic coloration occurs when the substances used for plumage maintenance change the color of the feathers, thereby becoming a signal themselves. Our review of cosmetic coloration in birds demonstrates that it is more widespread than currently realized, occurring in at least 13 bird families. Cosmetics have varied origins: they can be produced by the bird itself (uropygial and skin secretions, feather powder) or obtained from the environment (soil, iron oxide). Intraspecific patterns of cosmetic use (sex, age, and seasonal dimorphism) suggest that in many cases it may act as a sexual signal. However, more information is required on function, mechanisms, and costs to understand the evolution of cosmetic coloration and to confirm its signaling role.

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“…In the banded material, the spacing of bands is approximately 0.5 mm, close to the resolution limit of conventional light microscopes. Such a fine microstructure will be effective at scattering light, conferring the sun-blocking properties on the material to complement the sun-screening ability imparted by the previously reported (Saikawa et al 2004) chromophores. This realization in turn suggests the use of combined sunscreens and sunblocks to maximize the performance of thin layers of equivalent protective products for human use.…”

Section: (B ) Polymorphism Of Hippopotamus Sweatmentioning

confidence: 98%

Biomimicry as a route to new materials: what kinds of lessons are useful?

Reed

Klumb

Koobatian

et al. 2009

Phil. Trans. R. Soc. A.

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We consider the attributes of a successful engineered material, acknowledging the contributions of composition and processing to properties and performance. We recognize the potential for relevant lessons to be learned from nature, at the same time conceding both the limitations of such lessons and our need to be selective. We then give some detailed attention to the molecular biomimicry of filamentous phage, the process biomimicry of silk and the structure biomimicry of hippopotamus 'sweat', in each case noting that the type of lesson now being learned is not the same as the potential lesson that originally motivated the study.

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The red sweat of the hippopotamus

Cited by 71 publications

References 0 publications

Climate influences thermal balance and water use in African and Asian elephants: physiology can predict drivers of elephant distribution

Climate influences thermal balance and water use in African and Asian elephants: physiology can predict drivers of elephant distribution

Cosmetic Coloration in Birds: Occurrence, Function, and Evolution

Biomimicry as a route to new materials: what kinds of lessons are useful?

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