Singing Spider

The singing spider is a small*, predatory arachnid with a unique adaptation for hunting its favorite prey, cicadas. (*Its body length is roughly half an inch.) Its rearmost pair of legs have taken on an almost cricket-like shape, and it uses them like a violin bow on the tautest sections of its makeshift web to "sing" in different notes. These spiders tend to gather in small groups of four or five, each with their own note to play in chorus and time with the others, to mimic the mating call of a cicada or similar insect.
As soon as one comes close enough, the spiders leap from the web onto the cicada itself, piercing its carapace with envenomed fangs that begin the digestive process even as the insect drops, paralyzed and soon to be dead, from the air.
Most singing spiders are surprisingly pale-colored, almost pearlescent; the reason for this adaptation (or lack thereof) is unknown. They are somewhat dense, resembling jumping spiders in build, if significantly larger in scale. Each little "pack" of singing spiders is comprised of same-sex individuals, and during cicada and locust migrations, these packs can grow to number in the dozens in order to take advantage of the population of their prey.
Interestingly, singing spiders are quite capable of adapting their songs to different prey, including regional varieties and even different species like crickets. They are no more intelligent than any other predatory spider, but they have been observed learning very basic birdsong or even kinvaren whistling patterns. Without food as a reward for their efforts, these songs are quickly abandoned, but if a kinvar wishes to keep a small group of singing spiders, they need only feed the spiders after hearing the desired song to cement that pattern. Only if then deprived of food for a significant time would captive singing spiders seek to change their songs to whatever else they might be able to hear as possible prey.