Spiders, Pacific Northwest
Red orb weaver spiders belong to the family Araneidae. They can be distinguished from other web-weaving spiders by their highly organized webs. They weave their silk into circular grids, while other spiders, particularly cobweb spiders, weave much less organized webs.
Orb weaver spiders have 8 eyes and large abdomens that are usually globe-shaped. These spiders build more intricate webs than other spiders, but they have an advantage – while most spiders have 2 claws per foot, orb weavers have 3. They use their extra claw to help control the silk threads, as they spin their webs. Their webs, which are used to catch food & transmit mating signals, can span up to 2 feet in size. Like many other spiders, orb weavers eat their webs before rebuilding them.
As mentioned, orb weaver spiders usually have big, round abdomens. Some, however, have oddly shaped bodies. Spiders in the genus Micrathena have vibrantly-colored abdomens, featuring spines or spikes. For example, the arrow-shaped micrathena has an abdomen shaped like an arrowhead, and the spiked micrathena, has an oblong abdomen with a number of spiky projections.
Orb weaver spiders may look scary, but they are actually beneficial to humans. These arachnids catch house pests such as ants, mosquitoes, and flies in their webs, along with insect pests such as moths and beetles, which can harm crops.
These spiders typically do not bite, but when they do, their bite is only harmful to allergic individuals.
The spider in the photo is a red orb weaver that likes to build its web on grass & weeds growing out of water. This guy was on some grass stalks about 20 feet from shore, and was very busy swinging from grass stalk to grass stalk. It was quite fascinating to watch it going about the business of building its web.