National Geographic : 2014 Jan
photos (from top): rodger klein, Waterframe/getty images; anders garm; Joel sartore. art: Álvaro valiÑo NEXT The red eyes (above) of a blue star sea star can regenerate when arms are severed. Odd Couple The rock hyrax (left) is the size of a groundhog, yet it’s a close genetic relative of the towering African elephant. “What unites them is a common an- cestor,” says biologist Arik Kershenbaum. The two species, along with manatees, are part of a taxonomic group called Paenungulata, which diverged from other mammals 65 million years ago during climate shifts. They later began to diverge from each other to adapt in different habitats. Although they look nothing alike, hyraxes and elephants share some physical similarities, including spongy pads under their feet. — DS Wandering Eyes scientists have long known that sea stars have eyes. new research on Linckia laevigata (above)—one of the most common sea stars found on coral worldwide—illuminates how those eyes work. located at the tips of the arms, the eyes don’t function like human eyes. “We think they can only see the difference between light and dark in low resolution,” says neurobiologist anders garm. the difference has to do with brain size. human vision evolved to process more input as the human brain grew bigger and increasingly complex. sea stars, by comparison, have only a small collection of nerve cells that interpret visual information. even primitive eyesight, garm says, is sufficient for the animal’s needs. —Daniel Stone Bamboo is among the world’s fastest growing plants, sprouting more than three feet a day.