Orb-weaver spiders are known for their nets, the spiral wheel-shaped webs that are so often spotted hanging from garden shrubs or between the branches of trees. However, with more than 2,800 species within more than 160 genera worldwide, orb-weavers are the third largest family of spiders. And that means there are bound to be some spectacular stand-outs.
Two genus in particular, Gastercantha and Micrathena, show off the incredible variety of color, shape and pattern that orb-weavers are capable of wearing. Here is just a sampling of some of the unique species found around the world.
The genus name Gasteracantha derives from the Greek words "gaster," meaning "belly," and "acantha," meaning "thorn." It didn't take much imagination to come up with that combination for these little, spiky spiders! While they look like they could do some damage, the bite of spiny orb-weavers is harmless to humans.
The long horned orb-weaver, Macracantha arcuata, is also known as the curved spiny spider. It's easy to see how it earns either moniker. Two long spines resembling antennae extend from its sides. While its home range is southeast Asia and India, it can also be found in parts of the southeast United States where it is an (accidentally) introduced species.
Also quite spectacular are the Micrathena genus spiders, such as this Micrathena breviceps, or spiny-bodied spider found in Costa Rica. This species' defense mechanism is described by naturalist Philip Davidson:
"With the naked eye they stand out due to the arrow-shaped body being colored bright yellow contrasting with a black background. This combination is highly visible. As you might expect, the spider may not be attracting attention to itself inviting predators to prey upon it. This is warning coloration also known as aposomatic coloration. Any bird naive enough to ignore those colors and try to eat what would otherwise appear to be a tasty morsel, will come to grief as the spines on the spiders body lodge in the bird’s bill. Despite its best efforts the extract it, the bird initially cannot. As it remains stuck the spider is issuing from its body a noxious, foul tasting secretion. The bird when it finally does rid itself of the vilest tasting food it has tried will then forever associate black and yellow with the woeful experience and will never consume anything sporting those colors again."
While Gastercantha and Micrathena are found in tropical areas all over the world, there is only one species of Gasteracantha, native to the United States - the spinybacked orbweaver (Gasteracantha cancriformis). This species is also called — brace yourself — crab spider, spiny orbweaver spider, crab-like orbweaver spider, crab-like spiny orbweaver spider, jewel spider, spiny-bellied orbweaver, jewel box spider, smiley face spider, and crablike spiny orbweaver.
Though they look mighty, they're miniscule. At the largest end of the spectrum, some species can measure up to 1.2 inches from spike to spike. Most are much smaller.
If you're ever walking around in warm, tropical regions of the world or the rainforests of Asia, Africa and Australia, be sure to keep an eye out for these intricate little jewels of the spider world. You'll be glad for a run-in with one of these eight-legged wonders.