When I took this photo of a Hydromantes salamander shooting its tongue to catch a housefly, I was shocked how far out the tongue had been shot. It was only later, when I measured the length of the tongue skeleton in preserved salamanders, that I realized that the tongue skeleton was acting like a harpoon, and was shot completely from the salamander's body. The tongue is projected so rapidly that it travels to the prey under its own momentum.

We have since found that ballistic tongues have evolved at least three times independently among the lungless salamanders, and that tongue projection is accomplished with extremely high muscle power output, higher than that of any other vertebrate. I am currently working collaboratively to determine the physiological and biomechanical basis for this remarkably high performance.

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My work with Wendy Olson on feeding in tiny tadpoles demonstrates the influence of body size on the biomechanical options available to aquatic organisms.

As the tadpoles of the frog genus Hymenochirus became smaller through evolution, they abandoned the ancestral mode of suspension feeding and became suction-feeding predators on relatively large prey, and in the process they converged in function to a remarkable degree with teleost fishes.

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We tested whether or not the large "forehead" of the sperm whale, a greatly enlarged melon which is found in all toothed whales, could act simutaneously as a battering ram and as a damper, injuring a target and protecting the attacker. We also tested, using phylogenetic methods, if melon size in whales is correlated with male-male aggression.

Learn more in our paper (PDF).

Why have humans invented throwing devices? I have recently begun a collaborative project to determine how the human body interacts with ancient throwing technology (e.g. atlatls, boomerangs) such that performance improves, the chance of injury is decreased, and fatigue is reduced. A major goal of the project is to determine how biomechanics and physiology integrate to tune system performance.

Our results so far are very encouraging and informative. We have found that, when designing a projectile with high performance for hunting, one faces a conundrum: projectiles that are thrown with the greatest kinetic energy or momentum are not thrown very far or fast, and conversely, that projectiles that can be thrown very far or fast have little energy or momentum.

Ancient hunters have invented devices that may solve this problem.

My current collaborative work with Dr. David Carrier focuses on how locomotor forces are transmitted from the limbs to the trunk during running, and how this has changed in tetrapod evolution. Because the trunk is responsible for both locomotor and respiratory movements, conflicts can arise during running. Many lizards are unable to breathe and run at the same time because of a biomechanical constraint in the trunk; this constraint has consequences for the ecology of the organisms as well as implications for the evolution of aerobic activity in tetrapods. We are investigating how this locomotor-ventilatory conflict has been resolved via the evolution of trunk and limb musculoskeletal function to permit the sustained ventilation during locomotion that we see in mammals. Currently we are using a novel technique in which the extrinsic limb muscles act as force transducers: we record changes in muscle activity as we manipulate locomotor forces by applying perturbations to the dogs and lizards as they run.