Wikipedia
Amplectobelua is an extinct genus of late Early Cambrian anomalocaridid, a group of stem arthropods that lived as free-swimming predators during the first half of the Paleozoic Era. Like other anomalocaridids, Amplectobelua had a pair of jointed grasping appendages, large eyes, a limbless body, and a series of fins or swimming lobes on both sides that extended along the length of its body. It was smaller than the related Anomalocaris, however, and had a specialized grasping appendage, in which the spine on the fourth segment hooked forward to oppose the tip of the appendage, allowing it to grasp prey like the pincer of a crab. The fins differ as well; the front fins are very long and slender, while the middle pair of tail fins are specialized into a pair of long streamers, or furci.
Two species are known, Amplectobelua symbrachiata from the Chengjiang biota and Amplectobelua stephenensis from the later Burgess Shale. A. symbrachiata is known from complete specimens, while A. stephenensis is known only from isolated claws. A. stephenensis is more advanced, with the pincer being more specialized for grasping: the fourth spine is larger and the spines on outer segments are reduced.