supercontraction comparison

supercontraction comparison - Work, R . W. 1981 . A...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Work, R . W. 1981 . A comparative study of the supercontraction of major ampullate silk fibers of orb-web-building spiders (Araneae). J. Arachnol ., 9:299-308 . A COMPARATIVE STUDY OF THE SUPERCONTRACTIO N OF MAJOR AMPULLATE SILK FIBERS OF ORB-WEB-BUILDING SPIDERS (ARANEAE)t Robert W . Work Fiber and Polymer Science Program, David Clark Laboratory North Carolina State University, Raleigh, North Carolina, 27607 U .S.A. ABSTRACT An improved and simple technique is described for determining the magnitude of the recentl y observed phenomenon of supercontraction of major ampullate silk fibers of orb-web-building spiders . Supercontraction ratios obtained by the use of that method and also from an instrumental method ar e given. It is seen that only three levels of supercontraction are found among twenty two species o f orb-web-building spiders . The data are presented on the basis of taxonomic classification and ar e subjected to statistical analyses in order to determine which ones may be effectively differentiate d from the others . A contribution to the integerity of the wetted web is suggested as a function for the retractive driving force which underlies supercontraction. Mention is made of the possible usefulnes s of supercontraction as a taxonomic symptom . INTRODUCTION This paper is one of a continuing series (Work 1976, 1977a, 1977b, 1978, 1981) whic h have been concerned with the silks produced by orb-web-building spiders . In the third o f these, the discovery was announced of a very large axial shrinkage in water at roo m temperature of major ampullate silk fibers and its absence in minor ampullate fibers . It had been observed that the former retract to about one half their original lengths when they are wetted in an axially unrestrained condition . In the field of macromolecular chemistry this phenomenon is not unknown, being termed supercontraction . But it was quite unexpected, for although it can be induced in some natural and man-made fibers, i t can be produced only under drastic conditions of chemical swelling or elevated tempera - tures, or both . Thus its existence has encouraged an expanded physico-chemical investi - gation, having as its objectives the characterization of the phenomenon and the determi- nation of its basis at the molecular level . It is expected that the fruits of this research wil l be published in future papers of this series . But since orb webs are commonly wetted b y dew and rain, arachnological considerations were not disregarded . 'Grants from the Research Corporation and the National Science Foundation (currently CPE- 79-08905) supported, in part, the research described in this paper . 300 THE JOURNAL OF ARACHNOLOG Y In the earlier part of the study it was found that the magnitude of supercontractio n was remarkably uniform among all of the samples examined, as compared with thei r other physical properties such as axial force-elongation behavior . When one spider was found to have produced silk having an entirely different level of supercontraction, th...
View Full Document

Page1 / 10

supercontraction comparison - Work, R . W. 1981 . A...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online