Peter N. Witt

Spider Communication: Mechanisms and Ecological Significance

Concentrating on the complex spider communication system, this book assembles the most recent multidisciplinary advances of leading researchers from many countries to assess the peculiar role spiders play in the animal kingdom.Originally published in 1982.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

The energy budget of an orb web-building spider.

Abstract o 1. First measurements of increased total oxygen consumption of web-building Araneus diadematus spiders over resting animals are reported for nine webs of an adult female. 2. Analysis of movie pictures and web photographs results in an estimate of the number of steps and the amount of up and down movement which the animal used in construction of a single web. 3. Combination of both measures permits calculation of step energy, which can be added to the chemical energy involved in silk recycling, to lead to an appraisal of advantages and disadvantages involved in the daily construction of individual orb webs by single animals. 4. This is compared to data from the literature on the web-building strategies of other spiders.

The measuring function of the first legs of Araneus diadematus Cl.

Spiders deprived of one first leg or two front legs on the same side built webs changed in specific ways and never recovered. Web components were changed from control values to a statistically significant degree as follows: angle regularity and the number of radii decreased, the median central angle increased in size; the number of spiral turns and, in some cases, the spiral regularity decreased; the spiral area decreased relative to frame and central areas; the thread length decreased. No change could be detected in web shape or in the position of the hub. It is concluded that the first leg has a measuring as well as a locomotor function, that the second leg can partly substitute for that measuring function. Web changes following delegging reflect loss of normal adequacy in both of these functions. No evidence of right-left differences in leg function were found. All adaptation to the absence of one or two legs had occurred in the first web after the operation. The variation in control webs and the differential severity in reaction to delegging require evaluation of several animals and many webs; such extensive evaluation is made feasible by computer analysis of an array of points defining a web.

Ein Einfaches Prinzip Zur Deutung Einiger Proportionen Im Spinnennetz

Ausgehend von der Beobachtung, dass der Faden im fertigen Netz der Radnetzspinnen Aranea diadema, Zilla-x-notata und Meta reticulata den Weg zeigt, den die Spinne beim Bau der Netze zuruckgelegt hat, wird der Versuch gemacht die Einflusse zu differenzieren, die die Bewegungen bei der Anlage der Klebspirale gesteuert haben. Wenn wir annehmen, dass die Richtung der Spirale auf weite Strecken durch der. bequemsten Weg der Spinne von Radius zu Radius gegeben ist (d.h. den Weg, der den geringsten Kraftaufwand erfordert) und dass sie von diesem Wege nur vorubergehend unter dem Einfluss von ortlich auftretenden Sinneseindrucken abweicht, konnen wir einige der bekannten Proportionen der Klebspirale erkiaren. Ein Teil des bequemsten Weges ist der kurzeste Weg von Radius zu Radius, der weiterverfolgt eine logarithmische Spirale ergibt. Die Messungen fruherer Autoren haben einen solchen Verlauf der Klebspirale bereits erwiesen, ohne die Grunde dafur zu untersuchen. Weiter wird darauf hingewiesen, dass das fertige Netz nicht uberall dem im Bau befindlichen entspricht. Besonders die Proportionen der seitlichen Teile des photographierten Netzes weichen von denen des im Bau befindlichen ab, da hier das Be- und Entlasten der wagerechten Radien durch die Spinne ein Verziehen der Winkel bewirkt. Das Mittelstuck des Netzes zeigt im oberen und unteren Teil die Gesetzmassigkeiten des Baues reiner. An Hand von Beispielen einiger Radnetze, die unter dem Einfluss von neurotropen Substanzen gebaut worden sind, konnte ausserdem gezeigt werden, dass die verschiedenen Funktionen, die den Verlauf der Klebspirale beeinflussen, durch Substanzwirkung einzeln ausgeschaltet werden konnen.

FREE-HAND COPYING OF A GEOMETRIC PATTERN AS A TEST FOR SENSORY-MOTOR DISTURBANCE.

Detailed measurements of freehand copies of a geometric figure were made in order to assess the utility of such drawings for reflecting changes in skilled manual performance. For normal Ss, reliability was satisfactory only for short time-intervals and for certain parameters. However, measures of size of drawings and the placement of spiral lines appeared to show differential sensitivity to stimulant, tranquilizer, and stress conditions.