Tarantulas possess unique behaviors, including the ability to produce sounds. While many imagine these large spiders making a fearsome growl, their auditory capabilities are quite different. Understanding how tarantulas make sounds offers insights into their defensive strategies.
Beyond the Growl: Understanding Tarantula Sounds
Tarantulas do not produce a mammalian growl, as they lack vocal cords. Instead, their sounds are described as hissing, buzzing, or rasping noises. These sounds vary significantly between species, ranging from a soft rustle to a loud hiss.
For example, some Australian tarantulas are known as “barking spiders” or “whistling spiders” due to the distinct sounds they produce. The Goliath Birdeater (Theraphosa blondi), one of the largest tarantulas, creates a loud hissing sound audible from several feet away.
The Mechanics of Sound Production
Tarantulas primarily produce sound through stridulation. This process involves rubbing specialized structures on their bodies, similar to how a cricket chirps. These structures, often stiff bristles or hairs called setae, are found on various body parts, including legs, pedipalps (small, leg-like appendages), and chelicerae (mouthparts).
When these parts rub against each other, friction generates vibrations that create audible sound. For instance, some species rub setae on their chelicerae against their pedipalps, while others use structures on their leg segments (coxae) to produce sound.
In some cases, sound-producing structures resemble a “scraper” moving across a “file,” generating a sound akin to dragging a phonograph needle across a vinyl record. The location and type of these stridulatory organs vary among species, influencing the pitch and timbre of their sounds. While stridulation is the most common mechanism, some tarantulas may also produce a hissing sound by expelling air, though this is less prevalent.
Purpose of Tarantula Sounds
Tarantula sounds are primarily a defensive mechanism. When threatened, a tarantula often adopts a defensive posture, rearing up on its hind legs and displaying its fangs. The accompanying hissing or rasping sound serves as an auditory warning to deter potential predators.
This warning signal aims to startle an aggressor, giving the tarantula a moment to escape. The loud noise, combined with a threat display, amplifies the perceived danger, making the tarantula seem more formidable. These sounds are not typically used for communication within their own species, but rather as an inter-species deterrent.