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Spiders
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Credits to Mary Holland - Naturally Curious.
Molting Exoskeletons Like other arthropods, spiders have a protective hard exoskeleton that is flexible enough for movement, but can’t expand like human skin. Thus, they have to shed, or molt, this exoskeleton periodically throughout their lives as they grow, and replace it with a new, larger exoskeleton. Molting occurs frequently when a spider is young, and some spiders may continue to molt throughout their life. At the appropriate time, hormones tell the spider’s body to absorb some of the lower cuticle layer in the exoskeleton and begin secreting cuticle material to form the new exoskeleton. During the time that leads up to the molt (pre-molt period), a new, slightly larger, inner exoskeleton develops and is folded up under the existing exoskeleton. This new soft exoskeleton is separated from the existing one by a thin layer called the endocuticle. During the pre-molt period the spider secretes fluid that contains digestive enzymes between the new inner and old outer exoskeletons. This fluid digests the endocuticle that separates the two exoskeletons, making it easier for them to separate. Once the endocuticle is completely digested the spider is ready to complete the molt. At this point a spider pumps hemolymph (spider blood) from its abdomen into its cephalothorax in order to split its carapace, or headpiece, open. The spider then slowly pulls itself out of the old exoskeleton through this opening. Typically, the spider does most of its growing immediately after losing the old exoskeleton, while the new exoskeleton is highly flexible. The new exoskeleton is very soft, and until it hardens, the spider is particularly vulnerable to attack.  *This image is copyright of its original author
Credits to Nick Monaghan
Comment from The Silk Road: Apricia jovialis capturing an Araneid, in its own web. Possibly the first time this behaviour has been observed in this species of jumping spider and definitely the only time it's been photographed.  *This image is copyright of its original author
Credits to Tarantupedia.
The species Harpactira namaquensis is found in South Africa and Namibia and is considered to be one of the largest species in South Africa. Besides it's large size this can also be the most beautiful looking. See for yourself. 
The biggest spiders in the world for body size and mass, and a leg span around 28-30cm. Commonly known as Goliath Birdeater, the genus Teraphosa counts 3 species: T. blondi, T. apophysis and T. stirmi; this last described only in 2010. They live in the Amazonian rainforest from Guyana, Brazil and Venezuela.
Photo and information credits: J.P. Lawrence Photography "One invertebrate invariably found in just about any children's book about the Amazonian rainforest is the Goliath Bird Eating Tarantula (Theraphosa blondi). This individual was found hiding under a log and was larger than my hand."  *This image is copyright of its original author
Ceratogyrus species, most probably Ceratogyrus darlingi. It's not difficult found new species in this places, for example Ceratogyrus paulseni was described in 2005 from Kruger NP.
From Umkumbe Safari Lodge: Baboon spiders are actually a subfamily of the tarantula family. The reason for its name? Apparently the bottom segments of the legs resemble the fingers of the baboon species. Baboon spiders line their burrows with silk and they're not an aggressive species. These spiders will administer a very painful bite but it's not a venomous spider.  *This image is copyright of its original author
Credits to The Silk Road, image by Shikhei Goh.
Female ant mimic spider, possibly a Myrmarachne species. Myrmarachne, is a large genus of ant-like jumping spiders (Salticidae) that contains 186 species.  *This image is copyright of its original author
Credits to The Silk Road, image by Adam Parsons.
This very large Nephila pilipes was photographed by Adam Parsons and this was the largest specimen that he had seen of this species with a leg span that measured a huge 17.5cm. Spiders of the genus Nephila are abundant and conspicuous in many parts of the world, particularly in the tropics where they rank as some of the most spectacular denizens of closed forests. The large size of females and their diurnal habits have rendered various species of Nephila as some of the best studied spiders. All species construct large, asymmetrical orb-webs that include extensive yellow silk elements leading to the common name ‘golden orb-weaving spiders’.  *This image is copyright of its original author
@Tshokwane:
Bravo for this topic you initiated ! And as concerns your preliminary comments, I don't dare to imagine spiders and other ants, wasps, termites, praying mantis... if they had the size of extant lions and tigers... Probably, the human civilisation would not exist !
Credits to Caitlin Henderson.
Coastal Golden Orb-Weaver (Nephila plumipes). The only thing more impressive than the size and leg-span of the adult females is the size and span of the web. It is not unusual to come across an orb-web around one metre in diameter, with structural lines of the web extending several metres between trees. With this incredibly strong and sticky silk, Golden Orb-Weavers feed on anything from tiny flying insects such as fruit flies and mosquitos, all the way up to huge butterflies and even small birds.  *This image is copyright of its original author
Credits to Rob Crankshaw.
Staying on the macro theme, here we see a golden orb-web spider beginning to feed on a bee that it had entangled in its web. This photo illustrates perfectly how this particular spider got its name; from the colour of its web.  *This image is copyright of its original author
Credits to The Silk Road.
This remarkable looking jumping spider is a Plexippus paykulli, commonly known in it's native South East Asian countries as the Greater Housefly Catcher. Apparently this is quite the cosmopolitan species with a distribution spanning Africa, Asia and the American continent. A very adaptable spider indeed. This striking photo was taken by Husni Che Ngah and the vibrant colours are always an indicator of Husni's images.  *This image is copyright of its original author
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