In the absence of eyes, the fresh water polyp, Hydra magnipapillata, nevertheless reacts to light. They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, ...

What good is half an eye? Evolutionary biologists studying the origins of vision get that question a lot, and new research points to a possible answer. New findings indicate that, even in the absence ...

Left, a hydra stained in blue where the light-sensitive opsin gene is expressed. Right, two tentacle bulbs showing the arrangement of neurons and stinging cells (red), muscle fibers (green) and cell ...

In the absence of eyes, the fresh water polyp, Hydra magnipapillata, nevertheless reacts to light. They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, ...