This week for Flora and Fauna Friday it’s a group of insect entangling arachnids, the Orbweavers of family Araneidae.
The Orbweavers are a diverse group of pendulous predators common throughout the woods of Edisto. They can be found pretty much anywhere there’s something to stick their webs too and something to eat. These spiders quite literally come in all shapes, sizes, and colors to suit the various micro-habitats they prefer. However, all our common Orbweavers are similar in that they build a vertical web between openings in vegetation to trap flying insects. This web is covered in a sticky glue that adheres to anything that touches it. The spider then attacks the trapped insect, injecting it with venom, before wrapping it up in a silken coffin for later snacking. Females are an order of magnitude larger than males and typically colorful and complex in their abdominal shape. Today I’ll be highlighting four of the more common and recognizable species of the approximately thirty Orbweavers that can be found on our Island. Our stars today are the Spinybacked Orbweaver (Gasteracantha cancriformis), Black-and-Yellow Argiope (Argiope aurantia), Golden Silk Orbweaver (Trichonephila clavipes), and Giant Lichen Orbweaver (Araneus bicentenarius).
The Spinybacked Orbweaver is the most easily recognized of this already recognizable bunch. It’s a small Orbweaver that’s wider than it is long. Females are totally black underneath with a white mantle ringed in deep-red spines. They build oversized webs for their size and will flag their anchor threads with tufts of silk to help birds avoid the webbing. This saves our little spider from having to build a new web every time a cardinal careens through it.
The Black-and-Yellow Argiope is an Orbweaver commonly found in residential areas. Females have a large oval abdomen with a broken yellow border of bands on a black background, a silvery-gray thorax, and long two-tone legs. They prefer meadows, freshwater wetlands, gardens, and other densely vegetated habitats. They build webs lower to the ground than other large Orbweavers, often garnished with a vertical zig-zagging zipper of white silk down the center.
The Golden Silk Orbweaver (AKA Banana Spider) is the most common Orbweaver you’ll encounter in our forests. (Usually with your face.) Females are large and lanky with an aluminum-gray thorax, speckled orange abdomen, and long yellow legs with fluffy black legwarmers above the joints. They build massive webs that are often three-dimensional and disorganized. Unlike other orbweavers, they don’t rebuild their nest but instead just keep adding thread after each instance of damage. Their webs may be high in the trees or right at eye level. Their dragline silk is noteworthy for being a reflective gold color and unbelievably strong.
The Giant Lichen Orbweaver is one of the heftiest spiders you’ll encounter on Edisto. A female’s abdomen is roughly the size of a ping-pong ball and about the same shape. Unlike the others, she has a highly camouflaged coloration with a wash of soft green and spots of white over a background of browns. She builds her web from the low branches of a tree to the ground beneath. Then she tucks herself into a cozy corner between the leaves and mosses to wait for some unlucky soul to fall into her trap. Giant Lichen Orbweaver are even known to eat small vertebrates, most commonly Anoles.
