Poster Title

Swimming Mechanisms of Temperate Forest Ants

Grade Level at Time of Presentation

Senior

Institution

University of Louisville

KY House District #

23

KY Senate District #

23

Department

Dept. of Biology

Abstract

Swimming Mechanisms of Temperate Forest Ants (Camponotus pennsylvanicus and Formica subsericea)

Noah D. Gripshover, Evan M. Gora, and Stephen P. Yanoviak

University of Louisville

Abstract

Environmental challenges shape the evolution of animal behavior and morphology. For wingless terrestrial invertebrates like ants, pools of water on the forest floor are particularly dangerous. Here we show that ants can overcome this obstacle using a modified gait to transverse the water surface. We compared the locomotor morphology and swimming performance of two arboreal ant species that are common in Kentucky (Camponotus pennsylvanicus and Formica subsericea). We defined performance as speed and efficiency (deviation from a straight path) and determined the importance of individual legs to swimming performance using leg ablation experiments. We found that the front legs of both species are only used in propulsion; ants were slower, but showed no difference in swimming efficiency after ablation. Mid legs reduced swimming velocity and efficiency, especially for C. pennsylvanicus losing the most velocity after mid leg ablation. Rear leg ablation greatly decreased swimming velocity and efficiency, and these effects were greater for F. subsericea than for C. pennsylvanicus. However, these results are due to a loss in stability which affected performance. We also showed that both ant species are unable to swim if water tension is decreased by 10% or more. The results of this comparative study revealed the different mechanisms used by ants to overcome a common obstacle in terrestrial ecosystems. They also provide a foundation for understanding the evolutionary pressures faced by wingless organisms that live or forage in the forest canopy.

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Swimming Mechanisms of Temperate Forest Ants

Swimming Mechanisms of Temperate Forest Ants (Camponotus pennsylvanicus and Formica subsericea)

Noah D. Gripshover, Evan M. Gora, and Stephen P. Yanoviak

University of Louisville

Abstract

Environmental challenges shape the evolution of animal behavior and morphology. For wingless terrestrial invertebrates like ants, pools of water on the forest floor are particularly dangerous. Here we show that ants can overcome this obstacle using a modified gait to transverse the water surface. We compared the locomotor morphology and swimming performance of two arboreal ant species that are common in Kentucky (Camponotus pennsylvanicus and Formica subsericea). We defined performance as speed and efficiency (deviation from a straight path) and determined the importance of individual legs to swimming performance using leg ablation experiments. We found that the front legs of both species are only used in propulsion; ants were slower, but showed no difference in swimming efficiency after ablation. Mid legs reduced swimming velocity and efficiency, especially for C. pennsylvanicus losing the most velocity after mid leg ablation. Rear leg ablation greatly decreased swimming velocity and efficiency, and these effects were greater for F. subsericea than for C. pennsylvanicus. However, these results are due to a loss in stability which affected performance. We also showed that both ant species are unable to swim if water tension is decreased by 10% or more. The results of this comparative study revealed the different mechanisms used by ants to overcome a common obstacle in terrestrial ecosystems. They also provide a foundation for understanding the evolutionary pressures faced by wingless organisms that live or forage in the forest canopy.