How Did Spiders Evolve to Spin Webs?
WouterSpiders spin webs for several purposes. These include hunting, catching prey, and trapping insects. Many spiders use sticky silk to immobilize their prey. However, the types of webs created by spiders vary greatly. There are sheet-like webs, orb webs, and cobwebs.
A sheet-like web is composed of interconnected threads that create a concentric circle. This structure is restricted by the spider’s location. An orb web, on the other hand, is a very complex structure. It is composed of dragline silk threads radiating from a central point. This may be the earliest type of web to evolve.
While the structure of an orb web is similar to that of a sheet-like web, the spiders that make them have different characteristics. They may have an extra set of claws on their feet. The claws give the spider traction as it moves and grasp the web threads.
Spiders that build orb webs have been considered the ancestral state of spider evolution. It is thought that the first spiders to spin webs were around 200 million years ago.
The most recent diversity of spiders consists of two major radiations. They occurred in the Triassic period and the End Permian extinction. In the Triassic, the ancestors of modern spiders underwent adaptive radiation. This is reflected in the most diverse spider families. They are the linyphiids and theridiids.
Orb webs originated as substrate-bound webs. They then underwent an evolution that transformed them into aerial sheet webs. This transition was associated with the diversification of Orbiculariae, the family of spiders that spins these webs.
