People who are afraid of spiders – or, arachnophobic people, if you want to sound fancy and intellectual – are often compelled to scream when they unexpectedly encounter one of those eight-legged creatures. Ever wondered if this reaction is mutual? Do spiders scream?
No, they don’t scream; neither in fear nor in pain. Since spiders don’t have vocal cords, they can’t emit any sound from their mouths. This doesn’t mean that they are completely quiet critters, though. They can make sounds with other body parts, just as we can as well.
Some Australian spiders are even nicknamed “barking” or “whistling” tarantulas, carrying the sound they make in their name, even though most people would argue that the sound is closer to a hiss, or a scratching sound, which actually comes quite close to how it actually is produced.
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These spiders make their sound similar to the way grasshoppers and crickets do, by stridulation – the production of sound by rubbing together certain body parts. A lot of insects use their legs for this, but some are also capable of rubbing their thorax and their abdomen (the front and back half of their body) together to produce sounds and vibrations.
Often, stridulation, and the resulting hissing sound, is something a spider does when angry as a warning. It is therefore not recommended for those who keep pet spiders to provoke them until they stridulate – not only does it upset the spider, which, if it happens too often, could have long-term damages on its health, it can also bring a less experienced keeper in a dangerous situation.
Other than as a warning, some spiders also produce sounds when searching for a mate. Male jumping spiders, for example, try to impress females with a dance routine as well as a song! They produce vibrations by rubbing their abdomen and thorax together.
Usually, humans would not be able to hear the resulting sound. Researchers of the University of California, Berkely, use a laser vibrometer to turn these vibrations into something people can hear.
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In this way, they are capable of studying these songs and dances even more closely, and it becomes apparent that the courtship displays of the jumping spider are quite sophisticated, with songs consisting of a succession of verses that vary but are still connected by overarching themes.
Another spider, physocyclus globosus, also known as the short-bodied cellar spider, is known to cry out during sex. The reason is, again, stridulation, but this time, the friction that produces the sound is that of the male genitalia inside the female spider. Males that manage to produce this sound more often in their mate tend to produce more offspring. Researchers additionally suggest that males with the most rhythmic genitalia movement are also favored by female spiders.
Can Spiders Hear?
You might wonder whether spiders actually use the sounds they make to communicate with each other or whether the sounds that are audible to us humans are just a byproduct of the vibrations spiders can feel. As it turns out, it is a little bit of both.
Spiders do not have eardrums, so it is true that they cannot appreciate sound in the same way that we do. For a long time, scientists believed that spiders only received soundwaves with the vibration-sensing hairs on their legs, and thus could only “hear” things that were quite close to them, caught inside their nets, for example.
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A study published in 2016 changed this preconception. Researchers found that the jumping spider can also perceive airborne sounds. Since then, the question of the auditory sense of spiders has come under much scholarly scrutiny, and it has been found that some spiders can perceive sounds of an impressive range of frequencies, between 100 hertz (low and deep sounds) and 10,000 hertz (a high-pitched, screeching sound).
In a test in which researchers put tiny blindfolds over the eyes of ogre-faced spiders (this is their name, not an insult), and they nevertheless managed to catch their prey in flight, reacting to the vibration of its wingbeats.
Since it has been now shown that spiders can hear you talking from across a room, it seems commendable to be really careful when voicing opinions about icky, crawly creatures with way too many legs, in case they are vain!