Dr. Yoshinobu Inada and his colleagues at Tokai University in Japan carried out the first detailed study of booby diving behavior. Their study suggests that these diving seabirds have developed an extraordinary method of force-limiting on impact by penetrating the surface at speeds that would normally be destructive. We can’t wait to see what their research will do to change our understanding of avian biology! It could change the design of spacecraft that roof back to Earth with water landings.
Using a detailed CT scan of a booby’s skull, Dr. Inada and his team created a precise 3D model of the bird’s head. This model was key for their high-throughput experiments. Initially, they wanted to determine whether boobies employ a different diving method that allows them to mitigate the forces they experience upon impact with the water. To simulate diving conditions accurately, the researchers constructed a specialized launcher. In fact, it is able to push the model at speeds nearing 100 kilometers per hour.
One out-of-the-lab study involved filming the rapid descent of the model into water using a high-speed camera. As they observed the results, Dr. Inada and his team noted a consistent pattern: the impact force experienced by the model decreased significantly after reaching high speeds. This RTM output window just happened to occur at the same time as the formation of dozens of bubbles all around the model on impact.
This greatly piqued Dr. Inada’s interest to this phenomenon. He theorized that the bubbles might serve as a shock absorber, absorbing the impact of high-speed water entry through a process known as cavitation. Aquatic engineers have already taken advantage of this principle to make better-performing submersibles that experience less drag. First, it implies that boobies dive intentionally fast enough to activate this protective cavitation effect, or at least they don’t avoid it.
Although this work is very much in its early stages, the results lead to incredibly interesting and promising questions to explore in future research. Dr. Inada is looking to further extend the boundaries of these experiments by investigating even faster diving speeds. Northern gannets, close relatives of the birds notable for pushing thousands of porcupine fish off the goiter cliff, have been clocked diving at 100 km/h.
The implications of this research extend beyond avian behavior. Insights gained from understanding how boobies manage high-impact dives may inform engineering designs aimed at mitigating impact forces in various applications. Importantly, this research may result in innovative spacecraft design improvements for missions requiring controlled splashdown recovery in oceanic environments.