Tucked in a corner of an enclosure, swaddled in darkness, a tiny spider sleeps. But as the night progresses, he doesn't remain still. His tiny limbs twitch, his chelicerae tremble, his retinas flutter back and forth as though tracking the motions of something that isn't actually there. He is Portia fimbriata – the fringed jumping spider – among the most intelligent of the Araneads.