David L. Hu


On his book How to Walk on Water and Climb up Walls: Animal Movement and the Robots of the Future

Cover Interview of March 27, 2019

A close-up

The cover of the book is a water strider—an insect that stands on water as if it were land. As the animal rows, it generates waves on the water surface, similar to the ones created when a stone is thrown into a pond. The cover is just the first of several beautiful images featured in the book. The color image section contains a number of award-winning photographs including trout swimming upstream, mosquitoes being struck by raindrops, and ants linking their bodies together to build rafts.

rorotoko.comA water strider rows on the water surface, generating an underwater vortex with each stroke. The vortices are made visible by lighting the water from below and the addition of the pH-activated dye, thymol blue.

The table of contents includes short striking descriptions of each of the chapters. Swimming under Sand involves the sandfish—a lizard that swims through sand like it is water. Shape of a Flying Snake involves snakes that can spread their ribs like wings to glide through the air. Dead Fish Swimming involves trout that can use their flexible bodies to harvest the energy of rushing rivers so well that even dead fish can swim forward. Are Ants a Fluid or a Solid involves fire ants that can link their bodies together to build waterproof rafts to survive floods. Each of these chapters introduces the physical concepts necessary to understand each of these extraordinary phenomena.

Each chapter introduces the relevant background and can be read independently of the other chapters. I would like the reader to flip through the contents and find a topic that interests them, and then read the chapter. Of course, reading the book from beginning to end works too.