The St Andrew Cross Spider is a large spider found in much of eastern Australia.
It belongs to the genus Argiope, whose members are not only known for their size, but also for their brightly colored abdomen and unique cross shape woven into a network.
There are a few things you may not know about this striking spider web.
1. They got their name after being crucified
The zigzag in the cobwebs of St. Andrew's Cross is a large X-shape, which is also known as St. Andrew's Cross, as it is traditionally said that the Apostle Andrew was nailed to a diagonal cross with the letter X.
When the spider is in the middle of the cross, it looks as if it is suffering. But on the contrary, fate is reserved for the spider's prey.
A female St. Andrew's spider
2. Crosses may help them catch prey
Spider web ornamentation has long been a mystery, and there is still no clear consensus on its use. They are called stabilimenta, referring to an early belief that they help strengthen or stabilize networks.
The latest research shows that these elaborate designs have nothing to do with the structure of the net and nothing to do with the appearance of the net. The cross of the St. Andrew's Cross Spider is woven with blue-white silk that strongly reflects ultraviolet rays. Many flying insects are attracted to ultraviolet light, which can help them find flowers or fly through dense foliage, so the cross may lure unknowing prey into the spider's web.
3. The cross may intimidate predators
Another theory is that the cross helps protect spiders from predators, which at first glance may sound counterintuitive. If you don't want to be eaten by a bird or praying mantis, why mark your location with a bold X?
When the St. Andrew Cross Spider sits in the middle of X, aligning her outstretched legs with the cross's arms, it makes her look bigger and may scare potential predators. A spider that feels threatened may also bounce its web up and down, blurring her and the cross, which may further frighten or confuse the predator.
Web decoration can make spiders look bigger
4. It doesn't always weave X
The web woven by the St. Andrew's Cross Spider is highly variable. Some are woven into a thick X-shape with four legs, but can also be woven into other shapes. Sometimes, the nets they weave don't have any X at all.
5. Young spiders weave a "small pad cloth"
The St. Andrews spider also created another web decoration. Perhaps to protect the young spiders from the intense sunlight, they weave their webs into a thick cloth cushion. The Australian Museum likens it to a "silk table scarf". This seems to help hide spiders, allowing them to live in a secluded web.
6. Mating can be dangerous for males
St. Andrew's cross spider has "the opposite sex". Large, brightly colored spiders are females, while males are many times smaller.
Their mating seasons are summer and autumn, and a very cautious attitude is taken when male courtship seekers begin to wait near the top of the female net, and females often have multiple courturers at the same time, and some of them may lose their legs due to past attempts to attract unwilling females.
The male weaves a mating line in the female web and then makes it vibrate in anticipation of winning her affection. Both males and females have dual sex organs of left and right sex, but male organs break during mating, forming a "mating plug". This can help discourage competition from other males, but it means that each spider is limited to two matings. On top of that, males and females can only mate if the organs are matched from left to left or right to right, and males courting incompatible females may risk their lives and limbs. [Laughing and crying]
Two opposite-sex St. Andrew spiders
7. Pheromones help men find the right lady (or left lady)
Love can be a dangerous game for male St. Andrew spiders, but their search for the right partner isn't completely blind.
Although they can't safely approach to see if females are compatible, males seem to be able to assess female fitness by smelling pheromones in the web.
This gives them the opportunity to reconsider before entering the net. Studies of males who have already mated have found. Pheromones can help males identify females who have only mated once, but they apparently can't reveal whether their remaining sexual organs are on the left or right, so males are still gambling when they enter the female web.
8. They are not dangerous to humans
The size of the St. Andrew's Cross Spider can be intimidating, but it is of little harm to people. Its venom is not highly toxic to humans, and like most spiders, it is not usually aggressive toward humans.