Argiope aemula

長圓金蛛

Argiope aemula (Walckenaer) 1841

Oval St. Andrew’s Cross Spider

Family : Araneidae, Orb-Web Spiders.
Habitat: Low shrubs beside hiking trails at the fringe of primary and secondary forests.
Female: 25-30 mm. Male: 5-8 mm.
Distribution: Singapore, Malaysia, Indonesia, Thailand , the Philippines, Brunei (new record), Papua New Guinea, Vietnam, Sri Lanka, India, Taiwan, China, Southern Japan, Northern Australia.

The silk spinning organ of a female Argiope aemula (Orb-Web Spider) has 5 spinnerets (spinners).

When in resting position the spinning organ is in a circular position with the end tip of the 5 spinners meet in the center.

But when the organ is in action to spin silk on the pray, the spinnerets (not all) expended and erected and the many tinny tubes on each spinnerets ejected a fine tinny liquid form of silk hitting the pray. The watery silk harden almost within split second and wrap up the pray.

This female Orb-Web Spider of Malaysia did not spin silk all over the pray (an owlfly), it merely spray silk to the 3 major moving parts - first the wings, then the abdomen follow by the head. The whole silk spinning process took only couple of seconds. After which the spider return to her original position and wait as if nothing had happen.

Minutes later, the spider return to its pray and began sucking body fluid from the owlfly.

The Spinnerets - Spinners of a spider - Silk spinning organ of the female spiders

In this silk spinning organ, most spider species has just one pair of spinners. Some has as many as four pairs.

Each spinner has it own function.

There are small tubes in each spinners. All tubes are connected to the glands.

The number of tubes varies in each spider species between 2 and 50,000.

A spinneret is a spider's silk-spinning organ. It is usually on the underside of a spider's abdomen, to the rear. Most spiders have six spinnerets; some have four or two. They move independently and in concert to build webs.

Cribellum - additional silk spinning organ in some spider spicies.

Some spiders have an additional silk spinning organ called a cribellum situated in front of the normal spinnerets and consists of one to four plates covered in spigots

Silk Gland Name	Spinnerets Used	Type of Silk
Piriform	Anterior	Disk Attachment
Ampullate	Anterior/Median	Dragline and Web Frame
Aciniform	Median/Posterior	Wrapping silk, Sperm-web, Egg-cocoon (outer wall)
Tubuliform	Median/Posterior	Egg-cocoon
Aggregate	Posterior	Spiral parts of Sticky-web
Flagelliform	Posterior	Axial thread of Sticky-web

	This is a female Argiope aemula (Oval St. Andrew’s Cross Spider) Unlike many other Argiope spiders, the abdomen of an Argiope aemulais is oval.
	Argiope aemula spiders webs are vertically 1-2 meters above ground. The web of mature female spiders can be easily recognized by the X-shaped zigzag bands of white silk in the centre of the web.
	Photo Left : A female Oval St. Andrew’s Cross Spider. The brilliantly colored spider with silvery hair on the carapace sits head down in the centre of the web, and holds its legs in pairs in such a way that they appear to be aligned to the four arms of the letter 'X'.
	Photo Left : A male Oval St. Andrew’s Cross Spider. The males are dull in color and like the females, have the habit of pairing their legs. The male's webs are, however, decorated by a lace-like centre, instead of white bands in the shape of the letter 'X' in the female's. More about Male Argiope aemula spider of Malaysia Photo below : A lone male Oval St. Andrew’s Cross Spider by a lake in Sabah.