Welcome to the World of Spiders!

Wildlife Malaysia- Spiders!

Are you ready for some creepy-crawly action?

Spiders are some of the most amazing creatures of the world, thanks to their unique body structure and behaviour which distinguish them from all other forms of creatures: You will know a spider when you see one. However, astonishing as they may be, spiders are not exactly the most popular to humans. Unable to accept their hairy and eight-legged nature, most people tend to avoid, flee or even kill spiders with each encounter; and the constant portraying of giant spiders as villains in movies doesn’t help either. Arachnophobia, or the fear of spiders, is mainly caused by the lack of understanding.

Here at Wildlife Malaysia, we believe that knowledge is the key to understanding and appreciation, even towards creepy crawlies like the spiders. So now, just how much do you know about your spiders?

Anatomy (Body Structure)

There are a wide range of spiders out there: some huge, some microscopic, some look like ants, others like scorpions etc. How do you tell a spider apart from other insects or creatures?

Well, it is actually pretty simple, all spiders:

1. Have 8 legs, though sometimes one or more legs could be missing due to injury.

Lichen Huntsman Spider (Pandercetes sp.)

A beautiful lichen spider (Pandercetes sp.). Spiders may look very different from one another, but they will always have 8 legs naturally.

3. Have chelicerae and fangs, 99% of all spiders are carnivores. The orientation of the fangs may be different depending on the type of spiders.

Spider Fang

The face of a male Ptocasius Jumping Spider (Salticidae). All spiders have chelicerae and fangs. Note also the two prominent and rounded eyes in the middle which give Jumping Spiders excellent eye vision.

5. Have 6-8 eyes. 99% of today’s spiders have 8 eyes.

Spider Eyes

A Liphistius malayanus trapdoor spider, one of the most ancient spiders around. Even they have 8 eyes.

2. Produce silk, though not all spiders use the silk to build webs.

Spider Silk

A female Argiope Cross Spider wrapping up a blowfly before dealing the final blow. All spiders produce silk, and uses it differently depending on the need.

4. Have a body divided into two segments– cephalothorax (prosoma) and abdomen (opisthosoma).

 

Spider Anatomy

A common but large domestic Huntsman Spider (Heteropoda venatoria ♀). All spiders have a body that is divided into two segments, namely the cephalothorax (prosoma) and abdomen (opisthosoma). These two segments are connected via a pedicel which allows more flexible movements of the abdomen.

Most of the time, you can easily identify a spider based on the points above, though you might need magnifying glasses for tinier subjects.

 

Sensory Organs

Apart from a few group of spiders that hunt actively like the Jumping Spiders (Salticidae), Huntsman Spiders (Sparassidae) and Net-Casting Spiders (Deinopidae) etc., most spiders do not have great eyesight despite having 6-8 eyes! So how do they eat you ask?

A juvenile Malabar Hermit Spider going in for the kill-  Nephilengys malabarensis ♀ juv

A spider going in for the kill. Orb Web Spiders (Araneidae) are attracted to web vibrations caused by struggling prey.

Most spiders rely on force and vibration to sense, and eventually catch their prey (with the help of a web, of course!). A prey stuck on a spider web will not attract the spider’s attention so long as it doesn’t struggle.

Spiders are able to detect vibration, sense and even smells using fine bristles located throughout their legs.

A Tent Spider grooming itself- Cyrtophora sp.  ♀

A female Cyrtophora Tent Spider grooming itself. Note the fine bristles all over the legs, some of those are highly efficient sensory organs that enables the spider to sense and smell efficiently despite its poor eyesight.

 

Size

Spiders may range from microscopic at 0.43mm (male Patu marplesi) to frighteningly enormous at 30cm leg span (Heteropoda maxima).

Brachypelma boehmei

Spiders can reach gigantic sizes; this Mexican Fireleg tarantula is as big as an average’s persons palm!

Taxonomy (Grouping)

There are hundreds and thousands of flora and fauna all over the globe, and it will be ineffective, if not total chaos to understand, learn or research on them without a proper, scientific grouping system. This was why a Biological Classification of 8 taxonomic ranks, a scientific method to group organisms hierarchically was introduced. Without this system, we would not have been able to differentiate an insect from a spider, let alone all the scientific progress we have achieved thus far!

 

Spiders are arthropods- invertebrates (i.e. no backbone) with segmented bodies (i.e. division into cephalothorax and abdomen) and jointed appendages (i.e. segmented legs and palps).

Spiders are grouped under the Class Arachnida (hence the common term “Arachnids”) along with closely related arthropods such as mites, scorpions, harvestmen, whip scorpions etc.

Biological Classification

Without a proper classification for the flora and fauna found on Earth, it will be extremely challenging to learn more about them; since we do not know whether we are referring to the same organism during conversations!

Sex

Like humans, spiders occur in male and female sexes. Spiders are sexually dimorphic- male and female spiders look different from one another (just like a man being different from a woman in terms of appearance).  In most cases, it is fairly easy to differentiate adult male and female spiders by looking at their reproductive structures.

Adult males usually display swollen palps (or pedipalps) which store sperm required to fertilize the female spider.

Adult female spiders are generally larger than males, where some can be up to 20-30 times larger! All adult females possess a reproductive structure on the underside of the abdomen called the epignye which accepts the sperm from the males.

Swollen Palps of a male Nephila spider

An adult male Nephila kuhlii. Note the swollen palps (or pedipalps) that are used to store and inject sperm into the female genitalia.

Epigyne of a female Argiope spider

A female Argiope versicolor Cross Spider. Note the Epigyne, the female reproductive organ that receives sperms from the male spider’s palps. Fertilization is internal.

Moulting

Spiders are shielded by exoskeletons made out of chitin and proteins. The rigid and fixed armour provides the much needed protection for spiders but restricts growth, which is why spiders, like other insects, moult (in a process called ecdysis) in order to grow. It is also hypothesized that the onset of moulting is also caused by other metamorphosical factors.

In preparation for ecdysis, most spiders will lose their appetite and activeness, as the body releases enzymes that softens the existing skin to soon be shed. It is said that spiders undergoing moulting are not capable of breathing.

Tree-Stump Spider moulting- Poltys cf. illepidus ♀

A Tree-Stump Spider (Poltys cf. illepidus ♀) preparing to undergo moulting. Spiders undergoing ecdysis are very vulnerable to harm.

The “new” emerging body is initially soft and fragile, and will slowly harden with time. During this time, the spider is especially vulnerable to harm. The spider will not be able to feed as well until the new fangs harden.

Macracantha arcuata moulting

A female Curved Long-Spined Spiny Spider (Macracantha arcuata) just done emerging from its old skin. Note the yellowish colours of the “new” legs and body which will slowly turn black after a few days.

Spiders shed their skin approximately 5-10 times during their lifetime (larger and longer living spiders may moult more) and it is known that the shape (morphology), anatomy, colours and even behaviour will change with each moult.

 

Reproduction and Life Cycle

Spiders reproduce sexually through internal fertilization within the female. However, the mating process is rather “indirect”: After determining the suitability of the female spider, the male will release his sperms onto tiny, specialized webs before being “loaded” into his specialized pedipalps. The mating process involves the male getting to the underside of the female spider, and releasing his sperm into the female reproductive structure (epignye).

Copulation between a pair of Nephila pilipes

Copulation between a male and female Golden Orb Web Spider (Nephila pilipes). Note the relatively small size of the male! He will definitely get eaten if he’s not careful!

In reality however, the mating process is not that straightforward, mainly because of the relatively large sizes of female spiders. The males have to tread carefully so as to not be mistaken as food! In many instances, the males have to perform courtship rituals in order to entice or excite the female prior to mate, which include coordinated vibration of the female’s cobweb, erotic rubbing of body parts or even graceful mating dances.

A Siler semiglaucus fight- ♂ vs ♀

A simple mating dance between two Siler semiglaucus Jumping Spiders. Though not as elaborate and graceful as those from Australia and US, it is still a fairly awesome scene to behold!

A pregnant (or more correctly gravid) spider will then deposit hundreds of eggs on specialized egg sacs from which spiderlings will emerged from after a few weeks. Most mother spiders will stick around and care for their young, though the intensity of care varies from one spider to another.

Dendrolycosa sp. ♀- Mangrove Swamp Dendrolycosa

A Mangrove Swamp Mother Dendrolycosa guarding its egg sac closely, ensuring the continuity of her spiderlings, and thus her species.

Oxyopes birmanicus ♀ lynx spider guarding spiderlings

A mother lynx spider (Oxyopes cf. birmanicus) guarding her hatched spiderlings. Most spiderlings will stick around for awhile before dispersing. Until then, the mother is in charge.

In general, spiderlings will stay together on their mother’s sanctuary until their first or second moulting before heading out to see the world. These juvenile spiders will have to undergo a few more ecdysis before they become mature and capable of mating.

 

Distribution

Hungry Tarantula

Spiders are adapted to living in a wide range of habitats. Here we see a huge, burrowing tarantula.

Perhaps one of the main reasons why people are afraid of spiders is because of their abundance. Spiders are terrestrial and can be found throughout the world except for Antartica. Different types of spiders have evolved different tricks and mechanisms to allow them to thrive in specific environments. Some spiders excel at living underground, some on trees and shrubs, some near or even in freshwater!

So how do something as small as spiders travel and colonize such vast ranges of habitats?  Well, they certainly don’t do much of the travelling by foot! Most web spiders are capable of releasing their silk into the air and count on the wind to bring them to new places. YES, spiders can “fly”.

Argiope dang ♀ in-flight

A Cross Spider (Argiope dang ♀) gliding along with the wind. Spiders rely on this method to travel long distances.

 

Use of Silk

All spiders can produce silk using specialized structures called spinnerets usually located at the far end of the abdomen. Tarantulas were reported to produce silk through their feet (tarsi) as well. Despite the universality of silk production, not all spiders use the silk to construct cobwebs.

Cross Spider, web stabilimenta and exuvia- Argiope cf. doleschalli  juv ♀

A juvenile Argiope doleschalli resting in the middle of its cobweb. Web spiders rely heavily on their silks to build webs which help to capture prey. Note the thicker lines of silks which were deposited onto the main structure for extra stability.

Many spiders evolved different methods of using their silk, which include the use of silk-nets to catch prey (Deinopis sp.), silk trip-lines to sense prey (Liphistius sp.), silk “parachutes” for gliding long distances, silk safety lines as well as silken covers for sperms and eggs.

Trapdoor spider (Liphistius cf. desultor) and its trapdoor

Primitive trapdoor spiders (Liphistius) use their silk lines as traps that alert them when preys trip over them. The spider will then gush out, bite and drag the prey back into its burrow.

Scytodes pallida

A Spitting Spider (Scytodes pallida) spits silk in such haste that preys never stand a chance of fleeing.

Bites

Spiders will immobilize their preys before biting them and injecting venom (apart from Uloborid spiders that do not have venom, they just bite hard). While the prey is paralysed, the spider will secrete digestive enzymes that will, as the name suggests, dissolve the prey into juices healthy for the spider.

An angry tarantula (Coremiocnemis sp. ♀)

An angry tarantula displaying its threat pose. Provoke it any further and it will not hesitate to bite you!

Spiders are not known to attack and bite humans. Contrarily, they do bite only when threatened or provoked. Fortunately, to date there are no known venomous spiders here in Malaysia. Nevertheless, bites from large spiders will still inflict excruciating pain and cause inflammation and then infections if not treated properly.

Angry Malaysian Trapdoor Spider (Liphistius malayanus ♀)

Even the gentlest spiders (Liphistius malayanus) can become aggressive if you disturb it enough- best to leave them be. They may not be exceedingly venomous, but those large fangs will surely inflict a lot of pain!

 

Benefits to Humans

Spiders are efficient hunters or predators that help to keep the insect population in check. For example, Jumping Spiders (Salticidae) love to hunt and prey on a wide range of flies, most of which are annoying pests to humans. On the other hand, Huntsman Spiders, despite their scary looks, excel at hunting down cockroaches and even house geckos.

Blackwood Golden Orb Spider wrapping up food- Nephila cf. kuhlii

A Blackwood Orb Spider (Nephila kuhlii) feasting on blowflies- a pest often associated with sickness and diease.

Different spiders produce different types of venom with potentially beneficial applications. On-going research are looking at using spider venom to treat heart-related problems, erectile dysfunction as well as Alzheimer’s diseases. Of course, venom of deadly spiders can be used to formulate antidotes.

The highly tensile spider silk are also being applied in the development of high-tech and lightweight bulletproof vests. The differences in property between spider silk and silkworm silk may promise more applications in the future, especially to the fabric industry.

In Cambodia, cooked tarantulas are also considered as a local delicacy.

There you go! A short and brief introduction on spiders just for you! We hope that you have learnt a bit more about spiders now, and know that they are actually not as evil and creepy as we thought. Still, in order to truly appreciate the wonderful diversity of Spiders, we welcome you to check out the Spider Pages!

Thank you for reading and have a nice day!

 

 


* All photos in this article were taken by Tan Ji and are not to be used or copied without permission. For more details, please read Image- Terms of Use.

*For more info and guides on taking these type of Macro shots, please visit PixelsDimension.

* The authors attempted to make this article as simple as possible. Advanced topics will be included in the future.