In southern and eastern China, a large golden spider can often be seen sitting in a large circular web in the bush forest. Seeing this scene, there is actually no need to scream, and there is no need to take out your mobile phone to take pictures and annoy the museum magazine, because in addition to the rod bride introduced yesterday, it is probably today's protagonist - Argiope aemula.
Long circle golden spider. Image credit: wiki
At first glance, the long-round golden spider and the stick bride look quite similar, both are large spiders with golden yellow as the main tone, but the two are still very different. In terms of classification, the long-round golden spider belongs to the garden spider family (also known as the golden spider family), the golden spider genus; and the genus of the new woman in the rod line, although it was initially classified as the garden spider family, was later classified into the Xiao family (also known as the long-legged spider family), and was later promoted to the network neonatal family.
In terms of appearance, the abdomen of the long round golden spider is obviously shorter and thicker than that of the rod bride, which is very fat, while the foot is shorter relative to the body length. In a word, the rod bride is slender, and the long round golden spider is short. However, despite its stout stature, the 2-3 cm body length of the long-round golden spider is among the best among the members of the genus Golden Spider, and perhaps its other name, "Competitive Golden Spider", is how it comes from.
The rod-and-threaded bride has a thinner and longer abdomen and a relatively longer foot. Image credit: wiki
The back of the thorax of the golden spider is covered with a layer of silver hair, which is also a common feature of members of the genus Golden Spider: the genus name "Argiope" means "silver face" in Greek. The distinguishing feature of the golden spider is its abdomen. Its abdomen is yellowish-white in the dorsal front half and yellow in the posterior half, covered with black transverse bands. The black transverse band is looser against the tip of the abdomen and denser closer to the end. Sometimes, due to variations in body color, the yellow color of some oblong golden spiders is replaced by brick red, but the black bands are arranged in the same way.
Long circle golden spider. Image source: https://s3.amazonaws.com
In addition, if viewed from the ventral surface, the oblong golden spider has a yellow plate on the thorax and two longitudinal bands of yellow on the abdomen, all the way to the red spinning machine. The two longitudinal bands have outward branches, forming a split "well" glyph. Between the two longitudinal bands are six white spots arranged in a radial pattern.
The ventral surface of females with a long round golden spider. Image source: http://www.dipode-vie.net/
Like the bride of the rod, the long-round golden spider, as well as other members of the genus Golden Spider, are hermaphroditic. However, the male-female ratio of the long-circle golden spider is even more disparate, up to 10:1. Males are not as beautiful in color as females, with brown as the base color. Care should also be taken during mating, so as not to be treated as a snack by the female spider after mating.
Male (top) and female (bottom) comparison of the oblong golden spider. Image source: http://www.dipode-vie.net/
The web of the long round golden spider is the typical round web that is most in line with people's impression of the spider web. The whole circle net relies on several dragging wires to fix on the branches, and then some radial arrangement of radial wires constitutes the skeleton of the entire circle net, and then the long circle gold spider goes around in a circle, and the flexible and sticky silk catching spiral is wrapped around the radial wire, and finally forms a complete circle net. The long-circle golden spider will adjust the structure of the web according to its body size. In juvenile life, there are many radial filaments, so the silk catch is shorter, and the whole net is more sensitive to the impact of small insects, making it easier to catch small insects. When the body grows up, there are fewer nets and less wires, and the silk catcher is longer, so that the silk catcher can withstand a larger impact without breaking, which is suitable for catching large-sized insects.
The long round golden spider and its round web. Image source: https://s3.amazonaws.com
Another distinctive feature of the webs of members of the genus, including the long-round golden spider, is that between the radial wires, several white strips are woven with dense silk threads. These white stripes are called "stealth bands" or "support bands". Because these white strips are arranged in a zigzag zipper shape, they look like the English letters N, M, W, X, etc., so some rare and strange media will hype up under the name of "writing spider".
The so-called "Heavenly Book Spider" is actually a relative of the long round golden spider, the pleasing golden spider (A. amoena）。 Image source: http://fo.ifeng.com/a/20151009/41487437_0.shtml
There are many hypotheses about hidden bands, or supporting the function of bands. There is a theory that this strip can play a role in breaking the golden spider web to achieve the purpose of confusing predators. Evidence of this claim is that these bands are usually arranged in an X-shaped pattern on the web, and the golden spider also has a unique behavior, that is, when the golden spider will put eight feet in pairs, head down in the net, from a distance it looks like the "four legs" are arranged into an X shape, and the "four legs" are placed exactly inside the X stripe. Because of this unique image, the golden spiders are also known as the "St. Andrew's Cross Spider".
The long-circle golden spider and its X-shaped stealth band. Image source: http://farm8.staticflickr.com/
Another theory, the "trapping theory," has more experimental support. These white bands have been found to have a higher ability to reflect ultraviolet light, while many insects are more prone to ultraviolet light. Through measurements, it was found that larger golden spiders that needed more prey had a higher probability of weaving these bands, and that spider webs with these bands could catch about 60% more prey than spider webs without bands. However, some natural enemies of golden spiders, such as predatory bees, can catch golden spiders according to ultraviolet signals, and studies have shown that spiders with woven bands are nearly twice as likely to be attacked by wasps than without bands, so this can also explain why only some golden spiders will weave this conspicuous band.
The long-circle golden spider is wrapping its prey. Image source: http://taibnet.sinica.edu.tw/
Thanks to its large round web and special trapping devices, a mature golden spider can catch about 30 insects a day, and can prey on more than 2,000 insects in a single growth cycle, many of which are forestry and agricultural pests. Therefore, when you see this "big golden spider" in the future, don't destroy its web because you are afraid, it can be regarded as a guardian of agricultural and forestry production.