Experience and the orb web

Abstract

Abstract Cross spiders ( Araneus diadematus CI.) were confined in tubes for between 3 weeks and 194 days, from the period preceding building of a first web, or as adults. The first webs built after release were invariably found to be significantly smaller (shorter thread and smaller catching area) than those of littermates raised in large frames. The ampullate glands of nonbuilders were found to incorporate 14 C alanine at a lower rate than those of regular web‐builders. Pulling thread from glands repeatedly before release, or allowing animals to build several webs, brought speed of silk synthesis and size of webs to control values: this indicates that scarce silk supply is the cause for small webs after confinement. No differences in web size and pattern were found between mouth‐fed and web‐fed spiders, if animals were otherwise raised the same way. But adult spiders who had never been allowed to catch prey on the web disregarded flies in their webs. Differences in plasticity of web‐building and prey‐catching behavior are discussed.