Beavers make a dam foundation by wedging large branches or logs into the bottom of the stream bed. Next they add layers of branches, held together with mud, rocks, and loose vegetation. A coating of mud seals the structure. Beavers build lodges in which to live and raise young. Tree trunks, branches, and vegetation are woven together and coated with mud to make a solid structure.
Beavers then chew or dig tunnels and rooms inside the cone-shaped lodges.
Not all spiders spin huge webs to trap their prey, but these are the most noticeable spider structures. Spiders build webs from silk produced in their abdomen. The average garden spider makes a web with a total thread length of 20 to 60 metres. During the web-building process, the spider continually makes adjustments so stresses are spread evenly across the threads. Some spiders run as many as 80 threads radiating out from the centre of the web.