Preface; Scope and Structure; Acknowledgments; Contents; Contributors and Curators of Scholarpedia; Reviewers of Scholarpedia of Touch; 1 Introduction: The World of Touch; Touch in Invertebrates; The Evolutionary Origins of Touch; Lower Invertebrate Model Systems; Tactile Learning in Molluscs; The Arthropod Tactile Hair; The Arthropod Antenna: Elaborate Touch in Invertebrates; Touch in Vertebrates; The Lateral Line System of Fish and Amphibians; Evolutionary Origins of Mammalian Hair and Skin; Mechanosensation in Monotremes; Mammalian Vibrissal Systems

The Refined Vibrissal Sense of Aquatic MammalsActive Sensing Strategies and the Unusual Case of the Star-Nosed Mole; Varieties of Human Touch Sensing; Discriminative Touch as a Self-structuring Sensorimotor Activity; The Gentler Side of Touch: Affect, Sociality and Sensuality; Synthetic Touch for Haptic Interfaces, Robots, Prostheses and Virtual Worlds; Internal References; External References; Part I Comparative Touch; 2 Cockroach Antennae; Cockroach Antenna as a Tactile Sense Organ; Sensory System; Hair Sensillum; Campaniform Sensillum; Chordotonal Sensillum; Hair Plate; Motor System

Antennal Muscles and Their InnervationOutput Pattern; Central System; Mechanosensory Center; Motor Center; Interneurons; Behavior; Anemotactic Behavior; Evasive Behavior; Wall-Following; Obstacle Negotiation Behavior; Tactile Orientation; Electrostatic Field Detection; Internal References; External References; External Links; 3 Stick Insect Antennae; Antennae Are Active Near-Range Sensors; Antennae Are Dedicated Sensory Limbs; Four Adaptations Improve Tactile Efficiency; Matching Lengths of Antennae and Front Legs; Coordinated Movement of Antennae and Legs; Non-orthogonal, Slanted Joint Axes

Special Biomechanical PropertiesThere Are Specialised Sensors for Pointing Direction, Contact Site, Bending, Vibration, and More; Pointing Direction (Hair Fields); Contact Site (Tactile Hairs); Bending (Campaniform Sensilla); Vibration (Johnston's Organ); Internal References; External References; 4 A Spider's Tactile Hairs; The Exoskeleton and Its Sensors; Mechano-Sensitive Hair Sensilla; Types of Morphology and Arrangement; Proprioreceptive versus Exteroreceptive; Well Matched Micromechanics; Hair Shaft or Outer Lever Arm; Inner Lever Arm and Dendrites; Directionality

Physiological Responses of Sensory CellBehavioral Roles; Internal References; External References; 5 Tactile Sensing in the Octopus; Sense Organs in the Skin; Training Experiments; Taste by Touch; Learning to Make Skilled Movements; References; Recommended Readings; 6 Tactile Sensing in the Naked Mole Rat; Naked Mole-Rat Sensory World; Somatosensation; Skin; Teeth; Brain Structures Involved in Sensation and Perception; Computational Properties of Somatosensory Function; References; 7 Vibrissal Behavior and Function; Cross-Species Comparisons of Vibrissal Touch