Vanderbilt University, Nashville, Tennessee
What has retractable claws, hates water, and is covered in hair? No, I'm not referring to a cat - I'm talking about tarantulas. Tarantulas (Theraphosidae sp.) have many adaptations that allow them to survive in extreme environments, from the driest of deserts to tropical rainforests. A member of the arachnid family, tarantulas combine multiple strategies seen throughout the animal kingdom to defend themselves against predators looking for a spider snack. Tarantula hairs serve two functions. Most hairs help them to sense their environment and detect vibrations. |
Urticating hairs are located in the middle of the abdomen. Once they're kicked off, the tarantula has a bald spot until the next molt.
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New World Tarantulas have special urticating (stinging) hairs located on their abdomen, similar to porcupine quills or cactus spines. When threatened, they kick off these hairs in the direction of a predator's eyes or mouth.
During my undergraduate research with the Catania Lab, I used scanning electron microscopy to evaluate the different types of urticating hairs found on different tarantula species, as well as the effects that these hairs have on mammalian tissue in which they are embedded during a successful attack. Most of these hairs grow in a specific direction so that they burrow deeper into tissue, thus making them very difficult to remove (like a barbed arrow). These hairs usually only cause mild skin irritation for humans, but have a much more potent effect if they get into your eyes. If you're a hungry small mammal, breathing in these hairs can lead to asphyxiation. The devestating effects of these hairs were evident when I applied them to rodent eye, nose, and mouth tissue, mimicked the effects of grooming and blinking (a typical behavioral response to a tarantula attack), and captured the results via microscopy (pictured below).
Tarantulas get a bad reputation for their venom, but North American species are incredibly shy, only attack when threatened, and no species of tarantula in the world has the capability to kill a human. So perhaps their cool adaptations would be more appreciated if, instead of thinking about them as scary Halloween creatures, we thought about them more as like eight-legged kittens.
During my undergraduate research with the Catania Lab, I used scanning electron microscopy to evaluate the different types of urticating hairs found on different tarantula species, as well as the effects that these hairs have on mammalian tissue in which they are embedded during a successful attack. Most of these hairs grow in a specific direction so that they burrow deeper into tissue, thus making them very difficult to remove (like a barbed arrow). These hairs usually only cause mild skin irritation for humans, but have a much more potent effect if they get into your eyes. If you're a hungry small mammal, breathing in these hairs can lead to asphyxiation. The devestating effects of these hairs were evident when I applied them to rodent eye, nose, and mouth tissue, mimicked the effects of grooming and blinking (a typical behavioral response to a tarantula attack), and captured the results via microscopy (pictured below).
Tarantulas get a bad reputation for their venom, but North American species are incredibly shy, only attack when threatened, and no species of tarantula in the world has the capability to kill a human. So perhaps their cool adaptations would be more appreciated if, instead of thinking about them as scary Halloween creatures, we thought about them more as like eight-legged kittens.
From left to right: Costa-Rican Zebra Tarantula hairs, tarantula hairs embedded in a mouse eye, tarantula hairs (feathered appearance) snagged on mouse nose tissue and hairs