The bite of one tarantula species, Heteroscodra maculate, doesn’t just hurt: it hurts in a whole new-to-science way.
Sensory “transduction” is the conversion of a stimulus into a nerve impulse (action potential), which zips up to the brain, and then the brain decides what it means. And it usually means “OW!” in the case of this spider bite.
There’s some serious biological voodoo involved in transduction, but most noxious stimuli are converted to nerve impulses by members of the same family of ion channels in nerve cell membranes, the “Nav” channels (Nav1.7, Nav 1.8, Nav 1.9, etc). New members of this family of channels are still being discovered, and Heteroscodra maculate venom targets a Nav channel no one knew about until now. Ars Technica:
Two venom toxins from the tarantula species Heteroscodra maculate cause piercing pain sensations by targeting an ion channel in neurons not previously linked to pain, researchers report in Nature. In further experiments in mice, researchers found that these specific ion channels may underlie chronic abdominal pain in patients suffering from irritable bowel syndrome.
The finding—if validated in human studies—may help scientists unravel the complexity of pain perceptions and point to new ways to block the debilitating sensation. More specifically, the data suggests that finding a drug that could block this ion channel “represents a novel therapeutic strategy for diminishing the chronic pain in IBS and perhaps other pain conditions associated with mechanical sensitization, including migraine headache,” the authors conclude.