We show the surprising flow patterns created by a starfish larva, which churns the water around its body as it searches for algae, its primary food source. These vortices are unique to many invertebrates, which often struggle to obtain sufficient nutrients during the early stages of their development. Our video shows how millions of years of evolution have allowed the larva to master fluid physics in order to solve the unique dilemma of feeding at the microscale. But this innovation comes with a price: the vortices decrease the animal's swimming speed, and thus its ability to change locations and escape predators. By studying how physical forces shape the adaptation of simple animals, we hope to uncover the subtle manner in which physics shapes evolution.
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