Loris , common name for certain arboreal, nocturnal animals that feed on large mollusks, birds, insects, and fruit. Lorises generally move slowly and regularly, but can move very quickly when striking to kill their prey. They climb by grasping branches strongly with their opposable thumbs and big toes. The eyes are large and round and the tail is vestigial or absent. The slow loris of eastern India, Malaysia, Sumatra, Java, and the southern Philippines is a gray, robust animal about 26 to 38 cm (about 10 to 15 in) long. The slender loris of southern India and Sri Lanka is a smaller animal with long, thin legs. See also Lemur .