First, just as in vertebrates, there seems to be some kind of functional valve within a grasshopper’s body to prevent gravity-driven blood flow. Researchers at Virginia Tech showed that blood pressure is not related to gravity, supporting that new hypothesis. In addition, blood pressure in a grasshopper’s head is unrelated to its blood pressure in the abdomen, also evidence of valving.

At ASU, undergraduate and postdoctoral researchers in Harrison’s lab discovered that both heart and respiratory rates respond to body orientation and gravity. The grasshoppers that had their heads down (similar to a human standing on his or her head) had decreased heart rates to reduce fluid pooling in the brain. However, their ventilation rate increased. Harrison said they think this is because air sacs are being compressed around the brain so it’s struggling to get enough oxygen.

“So, grasshoppers have at least three ways to compensate for gravity; variation in heart rate, breathing rate and functional valving. And I’m sure there’s other stuff we don’t know about,” Harrison said.

As for other aspects of their physiology, insect bodies are capable of sophisticated responses to their active lifestyles.

“If you watch grasshoppers, they’re all over the place. They’re head up, head down, sideways,” Harrison said. “They’re very flexible in their body orientation, as are most insects. And now we know that when they change their orientation they have to respond to gravity just like humans, and they even show many of the same physiological responses. This is a dramatic example showing how similar animals are physiologically, despite how different they may appear.”

Written by Melinda Weaver, communications specialist, ASU School of Life Sciences

Sandra Leander

Manager, Media Relations and Marketing, School of Life Sciences

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