Tadpole — Ascidian

After twelve hours of frantic swimming, Pip's brushed against a rough, granite ledge. His light-sensitive eye confirmed the spot was shaded, and his gravity sensor confirmed he had reached the bottom. With a final, decisive surge, he pressed his head against the stone and triggered the chemical "glue" that would bind him for life. the swimming larva and its metamorphosis - Nature

A "gravity-sensor" that pulled him toward the safety of the dark seafloor. ascidian tadpole

Pip was born into a world of endless blue, a shimmering 1 mm speck of potential drifting in the current. Unlike the stationary, colorful "adults" anchored to the reef below, Pip was a , built for a single, desperate mission: to find a home. After twelve hours of frantic swimming, Pip's brushed

As he flicked his muscular tail, Pip felt the power of his , a flexible rod that made him a relative of the great whales and humans. His tiny brain, a cluster of only 170 neurons, hummed with data from two specialized organs: the swimming larva and its metamorphosis - Nature

Pip did not eat. He had no mouth and no stomach. He was a living battery, powered only by the energy his mother had packed into his cells, and he knew—in the way a cluster of neurons can "know"—that time was running out.