|Publication Type:||Journal Article|
|Year of Publication:||2008|
|Keywords:||barrier web, ontogenetic changes, plasticity, predator-prey relationship, St Andrews cross spider, stabilimentum, web decoration|
Web decorations occur in a wide range of spiders and are constructed using various materials such as leaves, carcasses or silk. Silk decorations, so called stabilimenta, have attracted most attention since they are an obvious feature of the webs of several orb web species and are highly visible to the human eye. Silk decorations are mainly discshaped, linear or cruciate. The functions of silk decorations remain a controversial issue. More comparative and experimental work is needed, apart from the assessment of environmental prerequisites for the construction of web decorations. I collected data on the occurrence and type of silk decorations, along with a measure of body size, for a population of the tropical spider Argiope argentata (Fabricius 1775) in the Bijagual biological reserve in Costa Rica. In addition, I recorded whether a barrier web was present or not. I found that whether a discoid or cruciate decoration was produced significantly depended on body size: smaller spiders constructed mainly discoid decorations whereas larger spiders constructed at least part of a cruciate decoration or none at all. Barrier webs predominantly occurred in smaller spiders and were rarely present in larger spiders. The data contradict those of an earlier census performed on the Galapagos Islands, which suggested that the difference in biotic and abiotic environmental parameters not only causes differences in variability of web building behaviour but near complete reversal.
Size dependent occurence of different types of web decorations and a barrier web in the tropical spider Argiope argentata (Fabricius 1775) (Araneae Araneidae)