I found this female Oriental Spiny Orb-Weaver spider Gastercantha cf geminata on a leaf at Kadri Park, Mangalore. Spiny orb-weavers is a common name for Gasteracantha, a genus of spiders. They are also commonly called Spiny-backed orb-weavers, due to the prominent spines on their abdomen.
Spiny Orb-Weaver spiders can reach sizes of up to 30mm in diameter (measured from spike to spike). Although their shell is shaped like a crab shell with spikes, it is not to be confused with a crab spider. I was using Canon EOS 6D Mark II with Canon EF 100mm f/2.8L Macro IS USM lens with Godox Ving V860C II E-TTL Li-ion Camera Flash and DIY diffuser.
In particular, Gastercantha genus, show off the incredible variety of colour, shape and pattern that orb-weavers are capable of wearing. 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.
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.
Rather than possessing sexual dimorphism, both male and female have black and white transverse bands on the abdomen. The abdomen has three pairs of long stout lateral spines. The female of the species is characterized by having a highly sclerotized “spiny” abdomen, which is a common feature of the genus. Female also has varying numbers of sigillae in both dorsal and ventral abdominal surfaces. Male is somewhat smaller than the female and with lesser colouration and abdominal spines.
The oriental spiny orb-weaver constructs vertical orb webs, normally within open spaces between the branches of tall shrubs and thorns.