Tentacles can refer to the elongated flexible organs that are present in some animals, especially invertebrates, and sometimes to the hairs of the leaves of some insectivorous plants. Usually, they're used for feeding, feeling and grasping. Anatomically, they work like other muscular hydrostats. Tentacles in marine animals The phylum mollusca includes many species with muscular hydrostats in the form of tentacles and arms (octopuses don't have tentacles: they've arms). Tentacles are longer than… (More on Tentacles)