In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainly like muscular hydrostats. Most forms of tentacles are used for grasping and feeding. Many are sensory organs, variously receptive to touch, vision, or to the smell or taste of particular foods or threats. Examples of such tentacles are the eyestalks of various kinds of snails. Some kinds of tentacles have both sensory and manipulatory functions.
Front view of land snail showing upper and lower sets of tentacles
Abalone showing pallial tentacles
Deep-sea ctenophore trailing tentacles studded with tentilla
The nautilus is an ancient pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina.
Nautilus
The first and oldest fossil of chambered nautilus displayed at Philippine National Museum.
Nautilus half-shell showing the camerae in a logarithmic spiral
Section cut of a nautilus shell