Stars of the Tactile World

This chapter addresses the supreme level of refinement found in many animals for analysing tactile and pressure information. It begins by looking at the sensory organ of the star-nosed mole. The mole’s star-shaped organ is used purely for collecting tactile information. The chapter then considers the Eimer’s organs which cover every appendage that comprises the nose, some of which are used for initial prey detection, while others are for identification. Owing to the number of Eimer’s organs, their tiny size, and the way that the sensory cells respond to patterns of stimulation across parts of each individual Eimer’s organ, the mole obtains exquisite detail on texture, almost to a microscopic level. The chapter also discusses the highly refined tactile sense of spiders, looking at how they rely on vibrations transmitted through the ground, the silk web strands, or the surface waves and air for prey detection and capture. Spiders are equipped with a variety of sensors to detect mechanical information, including fine hairs sensitive to wind movement and touch, and special organs called slit sensilla around the joints of legs that measure physical forces acting on the exoskeleton. Finally, the chapter studies the nature and function of integumentary sense organs or ISOs in both crocodiles and alligators. The heavily built bodies of crocodiles and alligators belie a high sensitivity, being able to detect the slightest changes in touch and pressure.