Sense Organs

Several exoskeletal structures are involved in sense perception. Various types of mechanoreceptor are involved in registering the exact position of, and deformation in, the various exoskele-tal regions and body parts, movements of surrounding objects, currents of air or water, vibrations in the substrate, and sound oscillations. Chemoreceptors are involved in registering and discerning the presence of various chemical substances; these receptors can be contact chemoreceptors (taste) or olfactory chemoreceptors (smell). Many of the sense organs take the form of setae (bristles, hairs, etc.), which are sensilla consisting of an elongated cuticular structure in connection with the sensory cell(s). A trichogen cell in the epidermis produces a more or less elongated structure, which can be variously shaped, often as a flexible hair, a rigid spine, or an arched dome. The hairs are usually connected to the surrounding cuticle by a joint, flexible membrane, and the sensory cell responds to deformations of the cutaneous membrane. The campaniform sensilla are rigidly connected to the surrounding cuticle, and they respond to tensions in the dome shaped cuticle.

The cuticle covering the elongated sensilla of olfactory chemoreceptors contains numerous narrow pores, allowing access for the airborne stimulatory molecules into the interior of the sensilla, where they come in contact with and stimulate the dendritic membrane of the sensory cell. The contact chemoreceptors are constructed according to the same principle, but they often contain a single larger pore through which molecules can get access to the sensory cell.

A characteristic feature of the visual system in insects is that both the compound eyes and the single eyes (ocelli) are covered by a transparent cuticle, the lens or cornea, through which light reaches the light-sensitive cells. Both the corneal cuticles and the cuticles used for construction of the other sense organs are constructed according to the common cuticular plan.

See Also the Following Articles

Chemoreception • Coloration • Cuticle • Mechanoreception • Molting

Further Reading

Andersen, S. O. (1985). Sclerotization and tanning of the cuticle. In "Comprehensive Insect Physiology, Biochemistry, and Pharmacology" (G. A. Kerkut, and L. I. Gilbert, eds.), Vol. 3, Chap. 2. Pergamon Press, Oxford, U.K.

Bereiter-Hahn, J., Matoltsy, A. G., and Richards, K. S. (eds.) (1984). "Biology of the Integument," Vol. 1, "Invertebrates." Springer-Verlag, Berlin. (See especially Chaps. 27—35.) Blomquist, G. J., and Dillwith, J. W. (1985). Cuticular lipids. In "Comprehensive Insect Physiology, Biochemistry, and Pharmacology," (G. A. Kerkut, and L. I. Gilbert, eds.), Vol. 3, Chap. 4. Pergamon Press, Oxford, U.K.

Hepburn, H. R. (ed.) (1976). "The Insect Integument." Elsevier, Amsterdam.

Hepburn, H. R. (1985). Structure of the integument. In "Comprehensive Insect Physiology, Biochemistry, and Pharmacology," (G. A. Kerkut, and L. I. Gilbert, eds.), Vol. 3, Chap. 1. Pergamon Press, Oxford, U.K. Kramer, K. J., Dziadik-Turner, C., and Koga, D. (1985). Chitin metabolism in insects. In "Comprehensive Insect Physiology, Biochemistry, and Pharmacology," (G. A. Kerkut, and L. I. Gilbert, eds.), Vol. 3, Chap. 3. Pergamon Press, Oxford, U.K. Neville, A. C. (1975). "Biology of the Arthropod Cuticle." Springer-Verlag, Berlin.

Wigglesworth, V. B. (1972). "The Principles of Insect Physiology." 7th ed. Chapman & Hall, London.

Nancy C. Hinkle and Beverly Sparks

University of Georgia

Linda J. Mason

Purdue University

Karen M. Vail

University of Tennessee, Knoxville

Land-grant institutions have teaching, research, and outreach (service) as their missions. Cooperative extension is the university's face to the state's citizenry, just as teaching faculty are the university's face to students and research faculty are the component visible to their academic peers around the world. In linking the university to the public, extension entomologists translate research results into practical applications and convey them to end users, while simultaneously apprising university researchers of real-world needs.

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