The head is where many sensing organs and the mouth parts are found. Like the adult, the larva also has a toughened, or sclerotized head capsule. Here, two compound eyes, and "chaetosema", raised spots or clusters of sensory bristles unique to Lepidoptera, occur, though many taxa have lost one or both of these spots. The antennae have a wide variation in form among species and even between different sexes. The antennae of butterflies are usually filiform and shaped like clubs, those of the skippers are hooked, while those of moths have flagellar segments variously enlarged or branched. Some moths have enlarged antennae or ones that are tapered and hooked at the ends.