About This Project

Many flying bats carry out two energetically expensive behaviors: wing beat and sonar emission. To economize these behaviors bats use flight muscles to also impose compression on the respiratory tract (RT), forcing air out during sonar emission. We will analyze possible RT adaptations by assessing changes in RT cartilage ring makeup in one day-old bats up to adult bats. Analysis of RT's from bats that cannot yet fly up to flying adults will elucidate the effects of this compression on the RT.

Ask the Scientists

What is the context of this research?

Bats synchronize wing beat and breathing in order to save energy while flying. Echolocating bats also synchronize wing beat and sonar calls to economize high frequency sonar emission. High frequency sonar, along with flight, is energetically expensive. Although flight muscles presumably help in compression of the lungs during flight, compression of the windpipe (primary bronchi and trachea) to the point of collapse would impede sonar emission. Therefore, reinforcement of the bronchial and tracheal rings would increase rigidity and provide increased resistance to the compressive forces imposed by flight muscles. Interestingly, we know that hyaline cartilage (which forms these rings), responds to increased mechanical load with deposition of calcium, thereby increasing cartilage rigidity.

What is the significance of this project?

Not only are bats the only flying mammals but many do so at night with limited visual assistance. The sophisticated sonar used by bats has allowed them to invade the night sky and become one of the most successful groups of mammal. Many of the adaptations associated with flight and sonar production are well documented, however, to date there is no analysis of the adaptations of the respiratory tract associated with wing beat and sonar emission synchronization. It has been argued that the energetic cost of high frequency sonar would be too high without the coupling of wing beat to sonar emission. Our study will shed light on adaptations that are vital for the synchronization of wing beat and high frequency sonar emission, allowing bats to exploit nocturnal aerial ecological niches.

What are the goals of the project?

Using an already established collection of specimens we will track the development of the respiratory tracts of two species (Artibeus jamaicensis and Carollia perspicillata) from day one postpartum up to adulthood. This will provide data from individuals unable to fly, individuals just learning to fly, and adult flying experts. These two species develop flight at significantly different rates, providing a means for teasing out changes associated with synchronization from changes due to age. We will clear and stain isolated respiratory tracts with Alcian blue and Alizarin red, providing clear discrimination between calcified and non calcified cartilage. This will allow us to describe the pattern of calcification and compare the percent of calcified rings to flight ability.