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Body shrinks under harsh conditions: marine iguana

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Marine Iguana / Pedro Vidal / LicensePD - Public Domain

The body length of marine iguanas shrinks in response to low food availability and energetic stress to reduce energy expenditure and increase foraging efficiency

FUNCTION
Summary

"Change in body length is considered to be unidirectional in vertebrates1, but we have repeatedly observed shrinkage in the snout-to-vent length of individual adult iguanid lizards. In two studies, one lasting 18 years and one 8 years, of two island populations of Galápagos marine iguanas (Amblyrhynchus cristatus), we found that individuals became shorter by as much as 20% (6.8 cm) within two years. This shrinking coincided with low availability of food, resulting from El Niño events. Body length increased again during subsequent La Niña conditions, when algal food was abundant. We found that lizards that shrank more survived longer than larger iguanas during harsh periods because their foraging efficiency increased and their energy expenditure decreased.

 

Shrinking in marine iguanas may be an adaptive response to low food availability and energetic stress.  Measurements of a cohort of adults more than 300 mm long during the strong 1992–93 El Niño event show that individuals that shrank more survived significantly longer (Fig. 2b). The mechanisms that determine whether and to what extent an individual shrinks during El Niño events remain unclear. Reduction in body length has been observed previously, and growth rates set to zero by definition, but to our knowledge this is the first report of shrinkage in adult vertebrates" (Wikelski and Thom 2000: 37)

 

[Note: The decrease in body size is the main strategy, no matter how it occurs. However, the paper mentions reabsorption of bone as the possible mechanism.]

About the inspiring organism
Med_800pxpav_2780 Marine Iguana
Amblyrhynchus cristatus BELL 1825
Common name: Meerechse

Habitat(s): Marine Intertidal, Marine Neritic, Marine Oceanic
Learn more at EOL.org
Some organism data provided by: TIGR Reptile Database
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Threat Categories LONG_VU IUCN Red List Status: Vulnerable

Bioinspired products and application ideas

Application Ideas: Reduction of the occupied volume in houses/buildings during very cold days to reduce heating. Flexible size packaging to meet different content size requirements.

Industrial Sector(s) interested in this strategy: Construction

References
Wikelski M; Thom C. Marine iguanas shrink to survive El Nino. Nature. 403: 37-38.
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