|
|
Golden
Orb Web Spider
Nephila maculata
Giant Wood Spider
Webs of steel: The Golden Orb
Web Spider is not the largest spider, but makes the largest and strongest
web. It gets its name from the golden colour of its silk.
|
|
Mangrove
and wetland wildlife at
Sungei Buloh Nature Park
|
Main
features: Large (female only) shiny legs with red
or yellow 'joints', builds large orb webs.
Female: 20cm across from
toe to toe, with a body about 3-5cm; males are only one-tenth
as big, at 5-6mm.
Status in Singapore: Common
in rainforest, secondary vegetation and mangroves
World distribution: Tropical
areas from Africa, India, China, Japan across Southeast
Asia to Northern Australia and the South Pacific islands.
Classification: Family Araneidae
which build orb-webs. Nephila maculata is the largest
of its genus. |
|
|
The
web can run from the top of a tree 6m high and up to 2m wide. Unlike other
spider webs, the Golden Orb Web Spider's web is not dismantled often and
can last several years.
Designed
to catch large flying insects, the web is slightly angled. It is not
a perfect wheel and is usually off-centre. To make its web, the spider
releases a thin thread into the wind. When it catches on something,
the spider walks along it trailing a stronger non-sticky thread. It
repeats the process in the centre of the line to form a strong Y-frame.
Around this, it spins the rest of the web out of sticky capture silk.
The silk is so strong that it can trap small birds, which the spider
doesn't eat. These trapped creatures often destroy the web by thrashing
around. To avoid such damage, the spider often leaves a line of insect
husks on its web (like the safety strip across glass doors!); or builds
smaller barrier webs around the main web. |

Photo from Joseph K H Koh
|
Breeding:
The male is many times smaller than the female, some are 1,000 smaller!
There are suggestions that it is not a case of the males being dwarves,
but the females being giants! The male is so tiny that he can live on the
female's web, stealing her food, often without her even noticing him. She
may not even notice that he has crept up and inseminated her! Nevertheless,
just to be sure, he usually does the deed when she is feeding. In some,
mating can take up to 15 hours! The female lives only slightly longer than
the male.
The
female buries her eggs in the ground. First she digs a shallow hole with
her strong mandibles and legs, which is then lined with woolly silk. She
lays her eggs on this silk, covers it with another woolly layer then covers
the whole assembly with camouflaging debris and soil. Laying can take 4
hours. Spiderlings hatch with their eggyolks still attached and don't have
fully developed mouthparts, venom glands, digestive tracts or spinning organs.
They may stay together at this stage. When they are fully developed, they
have to disperse or they will cannibalise each other.
Role in the habitat: Like other predators,
the spiders control the population of prey. They are in turn preyed upon
by other creatures such as birds. In New Guinea, some tribes consider them
a tasty treat. The Golden Orb Web Spider's venom is generally harmless to
humans and they rarely bite even if we blunder into and destroy their webs.
The bite is just a scratch. They are clumsy on the ground.
Uses by humans: Tribal people have long
used the webs of these spiders. In the South Pacific, the web silk is used
to make fishing lures, traps and nets. In the Solomon Islands, the spider
web is collected by winding it around sticks to make large sticky balls
which are suspended just above the water. Needle fish are lured to jump
out and get entangled in the ball. In Southeast Asia, people make a net
by scooping up the web between a stick bent into a loop. Spider webs have
been used as bandage to stop blood flow and used to make bird snares.
| In
modern times, the Golden Orb Web Spider's silk is set to become a
major product. The silk is almost as strong as Kevlar, the strongest
man-made material which is drawn from concentrated sulphuric acid.
In contrast, spider silk is drawn from water. If we could manufacture
spider silk, it would have a million uses from parachutes, bullet-proof
vests, lightweight clothing, seatbelts, light but strong ropes, as
sutures in operations, artificial tendons and ligaments. Studies are
now being done to have genetically engineered plants produce fluid
polymers which can be processed into silk! Spiders are not used to
produce silk fabric because Silkworm Moth caterpillars produce twice
as much silk and are easier to manage (for example, they don't eat
each other up!!). |
Nephila
antipodiana is another Nephila spider commonly seen in
the Park. It has no red "knees" and has a beautifully
marked abdomen. The one in the this photo is weaving her web
|
For more about spider
silk in general.
LINKS
About
the potential commercial development of Golden Orb Web silk
REFERENCES |
|
|
- Joseph K H Koh,
"A Guide to Common Singapore Spiders", BP Guides, Science Centre,
1989 (p. 24: habits, habitat, distribution, photos of spider and web).
- Rod Preston-Mafham,
"The Book of Spiders", Chartwell Books, 1991.
|