Funnel-web spiders aren’t just the most venomous arachnids in the world, they can also choose how deadly they want their venom to be.
The lethality of the spiders’ venom depends on the context in which they use it, according to a new study published in the journal PLOS ONE. With a complex cocktail of toxins in the venom, continued research could unlock new health benefits for humans.
The natural world’s most complex venom
“Funnel-webs have the most complex venoms in the natural world, and they are valued for the therapeutics and natural bioinsecticides that are potentially hidden in their venom molecules. Knowing more about how the spiders produce these is a step towards unlocking this potential,” study author Dr. Linda Hernández Duran, from James Cook University’s Australian Institute of Tropical Health, said in a press release.
Duran and her team collected four different species of funnel-web spiders, including the Border Ranges (Hadronyche valida), Darling Downs (Hadronyche infensa), Southern tree-dwelling (Hadronyche cerberea), and Sydney funnel-web (Atrax robustus).
They used several tests on the spiders, including prodding them with tweezers and puffing air at them. The results? Researchers saw variations in the spiders’ venom based on factors like defensiveness and heart rate.
“We mapped their behavior and measured their heart rate with a laser monitor to establish a proxy value for their metabolic rate. We then collected their venom and analyzed it with a mass spectrometer,” Duran said.
Slender Funnel-web Spider. Photo: Shutterstock
A closer look at spider venom
A few of Australia’s spiders are famous for being the deadliest in the world (at least to humans).
While spiders bite 30 to 40 people in Australia annually, only the male Sydney funnel-web has killed people, Science Alert reported. And in fact, the deadly arachnid hasn’t killed anyone since researchers found an anti-venom in 1981.
Many studies have looked at the molecular composition of the venom, but none had considered the spiders’s behavior, physical state, and environment. That led Hernández Duran and her colleagues to weigh the impact of those variables on the venom produced.
“With the Border Ranges funnel-web, the expression of some venom components was associated with heart rate and defensiveness,” Duran said. “The other species didn’t demonstrate this, suggesting that particular associations may be species-specific.”
“We showed for the first time how specific venom components are associated with particular behavioral and physiological variables and demonstrated that these relationships are context-dependent. We gained some valuable insights for further exploration and understanding of the ecological role of venom.”
