Organ Changes Enable Long Migration

photograph of white and brown bird standing on a rock with other birds in background

Biological Strategy

Bar-tailed godwit

AskNature Team

Image: Becky Matsubara / Flickr / Some rights reserved

Adapt Phenotype

Living systems evolve over time in response to selective pressures. Selective pressures are environmental factors that reduce the reproductive success of some individuals in a population. Genetic makeup (genotype) is one way in which living systems mitigate selective pressures, but another is adaptable phenotypes. A phenotype is an observable characteristic that can be thought of as the expression of the genotype, combined with modifications caused by the environment or developmental conditions. Individuals, populations, or ecosystems that have phenotypes capable of reducing the effects of selective pressures can survive. Some plants, for example, modify their leaf shape in response to changing environmental conditions. A single olive tree has variable leaf shapes on sunny compared to shady areas of the tree, yet the next year, those same buds may develop differently shaped leaves.

Search this Function

Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

Search this Living System

The eastern bar-tailed godwit can absorb and then rebuild tissue from its organs, allowing it to survive long-distance migration.

Introduction

The eastern bar-tailed godwit is a wading bird that undertakes an annual migration from Alaska to New Zealand. This 6,800 mile (11,000 km) journey is one of the longest migrations undertaken by any bird.

The Strategy

In order to survive the long journey, the godwit builds up huge amounts of fat to sustain it on its flight. In order to provide itself with enough room to house all of this extra fuel, yet also keep its weight down for flying, the godwit absorbs up to 25 percent of the tissue comprising its , s, and alimentary canal. Only when the bird completes its migration are these organs reformed in their entirety.

The Potential

The ability to absorb and then rebuild tissue from organs could be used to help humans survive long-distance space travel. By absorbing and then rebuilding tissue from organs, astronauts could reduce the amount of space and resources required for a long-distance space mission.

“A grotesque phenomenon known as autophagy or autocannibalism, in which an animal eats portions of its own body, can be used as an aid to migration. Intriguingly, the eastern bar-tailed godwit (Limosa lapponica baueri), a wading bird, exhibits a similar but more subtle behavior that appears to assist its long-distance migration. As revealed in 1998 by Groningen University researcher Dr. Theunis Piersma and Dr. Robert Gill from the U.S. Geological Survey, before setting out on its 6,800 mile (11,000 km) migration from Alaska to New Zealand, this bird builds up huge amounts of fat to sustain it on its flight. In order to provide itself with enough room to house all of this extra fuel, yet also keep its weight down for flying, the godwit absorbs up to 25 percent of the tissue comprising its liver, kidneys, and alimentary canal. Only when the bird completes its migration are these organs reformed in their entirety. This is the first time that partial organ absorption and subsequent reconstitution has been documented in a species of migratory bird.” (Shuker 2001:71)

Last Updated August 18, 2016

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

Marshall Editions Ltd. | 26/02/2021 | Dr. Karl P. N. Shuker

embedly preview

Reference

Journal article

Guts don't fly: small digestive organs in obese Bar-tailed Godwits

Piersma, T.; Gill, R.E., Jr

AskNature