As promised: WARNING ~ spider shot

[JBW]

[Shadowman]

Any theories on the length of their legs, is it to support their body mass?

[JBW]

Any theories on the length of their legs, is it to support their body mass?

That is the type of question I find hard to resist. Body mass certianly comes into the equation but so does web versus ground dwelling.

Spiders have evolved to occupy diverse niches. Some families of spiders, such as orb weavers (Araneidae, Tetragnathidae, and Uloboridae), cellar spiders (Pholcidae), and cobweb weavers (Theridiidae), are rarely out of contact with their webs. These web-dwelling spiders have specialized claws at the end of their legs that allow them to grasp silk strands and hang from a web (7). Because web-dwelling spiders have adapted to hanging from their webs, rather than walking long distances over the ground, their legs tend to be thinner and longer than similarly sized ground-dwelling spiders, whose legs are generally shorter and more robust. Some web-dwelling spiders have high burst performance, however, because they must quickly subdue prey that has been caught in their web. Ground-dwelling spider families include wolf spiders (Lycosidae), fishing spiders (Pisauridae), and tarantulas (Theraphosidae); these forage by wandering along surfaces such as vegetation, the ground, or walls to encounter prey. These spiders tend to have robust walking legs since they need to support their body weight, and most have high endurance performance to encounter and catch prey (10). A third ecomorph, represented by funnel weavers (Agelenidae), have a web and forage on it but do not grasp each silk strand with specialized claws. Instead, they run across a sheet of silk by flattening their tarsi across multiple web strands (10). As a result, they can run equally fast on the ground and on their web. Funnel weavers have high burst performance but tire quickly.