Male new-casting spiders eyes shrink by 25 percent

The eyes of male net-casting spiders shrink by 25 per cent when they've entered adulthood, but females' eyes increase in diameter by 21 per cent. Net-casting spiders use their secondary eyes for motion detection to catch prey at night by entangling them using a silk-spun net. Researchers say that the reason for the spiders' change in eye size may have to do with their hunting strategies - males lose the ability to spin food-capturing nets as they become adults, so they don't need such large eyes, while females retain their hunting abilities. Pictured top left is a females' eyes before transitioning to adulthood, and bottom left after maturing to adulthood. Pictured top right is a males' eyes before maturing, and bottom right after maturing.