A "gravity-sensor" that pulled him toward the safety of the dark seafloor.
A "light-eye" that told him to swim away from the bright surface where predators lurked. ascidian tadpole
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: A "gravity-sensor" that pulled him toward the safety
The is a tiny, free-swimming larva that represents a fleeting moment of mobility in the life of a sea squirt. Though it measures only about 1 mm and lives for just a few days, it possesses complex features—like a primitive spinal cord (notochord) and a simple brain—that it will eventually digest to become a stationary adult. The Great Descent of Pip His tiny brain, a cluster of only 170