Bill Used As Heat Exchanger for Thermoregulation

black and white bird with orange beak sitting on a brown tree branch

Biological Strategy

Common toucan

AskNature Team

Image: Gilles Pretet / Flickr / Some rights reserved

Distribute Energy

Many forms of energy are naturally available, including kinetic, potential, thermal, elastic, radiant, chemical, and more. All living systems require energy to carry out their many activities. Energy isn’t a physical object that can be held, so it also can’t be pushed, pulled, or carried. However, it can be transmitted or transformed. For example, the golden-scale snail has a tri-layered shell that dissipates, or transfers, forces from a predator biting down on it, thereby minimizing damage to its soft body inside the shell.

Search this Function

Maintain Homeostasis

When a living system is in homeostasis, it means that internal conditions are stable and relatively constant. For example, a human’s internal temperature is approximately 37 degrees Celsius (98.6 degrees Fahrenheit) unless there’s an illness. The human body maintains this temperature despite external ambient temperature. However, as with all physiological processes, maintaining homeostasis requires communication and coordination. So living systems have ways to detect changes from the norm, mechanisms to cause an adjustment, and negative feedback connections between the two. A desert lizard called the Gila monster offers a good example of maintaining homeostasis. The lizard goes from eating large meals to fasting for extended time periods. To maintain its blood sugar levels at a steady level, when food is scarce, its endocrine system releases a hormone that raises its blood sugar levels.

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

Bill of toco toucan acts as a heat exchanger to regulate body temperature by adjusting blood flow

Image: Lip Kee Yap /

“The toco toucan (Ramphastos toco), the largest member of the toucan family, possesses the largest beak relative to body size of all birds. This exaggerated feature has received various interpretations, from serving as a sexual ornament to being a refined for feeding. However, it is also a significant surface area for heat exchange. The toco toucan has the remarkable capacity to regulate heat distribution by modifying blood flow, using the bill as a transient thermal radiator. Results indicate that the toucan’s bill is, relative to its size, one of the largest thermal windows in the animal kingdom, rivaling elephants’ ears in its ability to radiate body heat.” (Tattersall et al. 2009:468)

Sleep-state transitions witnessed as changes in bill temperature. This is a thermal imaging video showing transient changes in bill temperature that occur during sleep while the bill is tucked between the wings. Time-lapsed data obtained at 10-s intervals. Total frames = 724, total length = 2.7 hours. Filmed by the Tattersall Laboratory.

Last Updated May 19, 2017

References

Journal article

Heat Exchange from the Toucan Bill Reveals a Controllable Vascular Thermal Radiator

Science | 23/07/2009 | G. J. Tattersall, D. V. Andrade, A. S. Abe

embedly preview

AskNature