Tag Archives: jorogumo

Along Came A Spider

17 Aug

 

Hi blog.

 

Avid readers (surely there are one or two of you out there…) might remember that I promised one day I would write a post on a certain spider.  Well, that day has come.

 

I’ve written up on most of Japan’s large web spinners – jorogumo and onigumo spring to mind.  This time I’ve managed to get some reasonable shots of the other major orb weaver – Argiope amoena.

This spider seems to lack a common name in English, so I’ll use the local name koganegumo (黄金蜘蛛) here.

 

This spider belongs to the same genus as the wasp spider (A. bruennichi) and the St. Andrew’s cross spiders (A. keyserlingi and A. aetherea), to which it bears a strong resemblance.  Like its close relatives, the female spins a web with some kind of stabilimentum, or web decoration, and sits in the middle of the web, head downward, and the legs stretched out into an X shape.

Look what I just found! The legs are held out into an X shape, and you can see the web decoration.

The shape of the stabilimentum varies between individuals, but is typically a combination of one to four / and \ patterns extending from the centre of the web.  The best known is the X-shaped combination.  The exact function of the stabilimentum is unknown, although research suggests that it reflects ultraviolet light which attracts prey insects.

A clearer view of the stabilimentum.

 

The female koganegumo grows to just under 20 mm in body length, and has a wide abdomen.  The abdomen is decorated with wide horizontal gold and brown bands.  The male grows to a mere one fifth that size and is typically a dull brown.

It is found throughout Japan minus Hokkaido, and its range also includes the Korean peninsula, Taiwan, and parts of China.  Apparently, however, it is quite rare here in Saitama and is listed as an endangered species on a prefectural level!

 

This spider has a number of regional names, some of which are shared with the jorogumo.  (Actually, a lot of people are actually unaware of the differences between the two – they tend to lump spiders into a single category, usually a visceral conglomerate of fear and disgust)

 

Like their close relatives, these spiders have a single year life span, with males mating once or twice – they never survive a second mating – and eggs are laid in summer.  The hatchling spiders survive over winter, but the adults die during autumn.

Larger than life. Actually, she’s quite a pretty spider, don’t you think?

 

While not embedded deeply in folklore like the jorogumo, the koganegumo used to play a part in children’s games – its web was used to catch cicadas.

Furthermore, there is a tradition of pitting female spiders against each other in the old Satsuma fief in modern Kagoshima.

Apparently, this was started in 1592 by Yoshihiro Shimazu, lord of Kagoshima, as a means of instilling fighting spirit among his men.  The event continues to be held today and is designated an important cultural event.

 

The spiders are deprived of food for three days before the fight.  They are placed on a horizontal stick and forced to encounter.  The winner is the spider which forces its opponent to fall, starts to wrap it in silk, or succeeds in biting its foe.

It seems that intervention prevents arachnidian deaths.

As seen on NHK news…

 

I’m sure you’ll agree that the koganegumo is a fascinating and beautiful spider.

Faceoff

7 Aug

Like a scene from Alien vs. Predator… only for real.

An orb-weaver spider has set up home in the mandarin tree in our tiny garden.  Praying mantises also take advantage of the greenery and the insects it attracts.

What happens when two ambush hunters meet?

 

 

 

 

 

(In this case, nothing.  The mantis didn’t walk into the spider’s web, and the spider didn’t get within striking range of the mantis.)

Her Ladyship

19 Nov

Great horns she had, and behind her short stalk-like neck was her huge swollen body, a vast bloated bag, swaying and sagging between her legs; its great bulk was black, blotched with livid marks, but the belly underneath was pale and luminous and gave forth a stench.  Her legs were bent, with great knobbed joints high above her back, and hairs that stuck out like steel spines, and at each leg’s end there was a claw.

 The Lord of the Rings

 

It is said that humans instinctively find certain features attractive – large eyes, for example – and this is why babies (both human and animal) appeal to us.

In the same vein, a dislike of sudden scuttling movement, multiple appendages and the like is also thought to be inherent.  Humans have an a priori fear of spiders.

 

Now, I am NOT particularly scared of spiders.  Growing up in suburban and semi-rural South Australia brought me into frequent contact with black house spiders, white-tailed spiders and redbacks.  I once brought a red-headed mouse spider home for identification; and for many years, one of my designated household jobs was the removal of huntsman spiders – some with a leg span of around 20cm – from the kitchen and neighbour’s house.  Even today, I am quite happy to let one of the small wolf spiders that enter my house crawl onto my hand so I can take it back outside.

 

But there is one spider that does manage to give me the willies.  Jorogumo.

What the spider looks like moments before you walk into its web..

A member of the golden orb-web family, Nephila clavata is beautifully coloured.  The females are large for web spinners – body lengths of 25mm are not uncommon.  They also have very long legs and spin large webs, up to a metre across.  The whole trampoline effect intensifies their already rapid-but-jerky movement.  As I said, humans are predispositioned to dislike this.

I also mentioned their bright colouring – yellow and black striped legs with a blue-ish tinge near the body and a yellow and black abdomen, often with a red band.  In nature, bright colours, particularly red, are usually a warning sign – “Mess with me and you’ll regret it”.

However, these are not aggressive spiders, and their venom is not known to be dangerous to humans.

A spider viewed from the back.

I should point out here that practically every spider is venomous. There are just a number of factors determining whether or not the bite is dangerous – the ability of the fangs to penetrate human skin, the type of venom, the volume injected, individual allergic reactions, and the presence of bacteria on the spider’s fangs.

 

The jorogumo (女郎蜘蛛) is sometimes confused with spiders of the genus Argiope (the genus that includes the St. Andrew’s cross spider), particularly Argiope amoena, known locally as koganegumo (黄金蜘蛛).  I hope to write about these spiders in a later post.

 

There are two popular theories as to the origins of the jorogumo’s name.  The more common one is 女郎, basically a prostitute; the other is 上臈, a high-ranked court lady.  The former name is also sometimes shared with a mythical creature in folklore (also written 絡新婦 – “ensnaring bride”) that possesses some arachnidian traits.

 

“Jorogumo” by Toriyama Sekien. A public domain image.

Old stories tell of men meeting a beautiful woman and falling for her charms (sometimes marrying them, sometimes being led to their house)  When the man falls asleep, the woman transforms into a giant spider, binds him in her web, and devours him.  Eventually a young samurai sees through the deception and kills the spider.

A variation has the woman carrying a child (possibly representing the spider’s egg-sac).  The woman asks the samurai to hold the child.  The samurai sees through the disguise and makes to slash at the woman and child.  The child screams, and the samurai escapes.  He returns the next morning to find a giant spider crushed under a huge rock, and countless human skulls under the house.  Had he carried the child, he would have been pinned down when it transformed into the rock and been easy prey for the jorogumo.

 

Typical of many spiders, mating is a dangerous affair for the male – he often ends up getting eaten as part of the bargain.  His chances of survival are best if the female has just eaten or has just molted.

 

A female in the 20mm+ class, with remains of her last meal still wrapped up. Many thanks to workmate Mat for this shot.

As I write this, the spiders are approaching the final stage of their life cycle.  Eggs are laid in late autumn and early winter and hatch in the spring.

A big thank-you to workmate Mat, who took time out to help me find and photograph specimens for this post.

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