The Australian funnel spider (Atrax robustus) is known to be the deadliest in the world. Its venom is extremely powerful, although it has now been discovered that it is irregular and that the arachnid has the ability to change it depending on the context and circumstances it faces, according to a study by James Cook University (Australia), published in the journal specialized magazine Toxicon.
In their work, the researchers verified that the expression of some components of the venom was associated with heart rate and defensive attitude, whether or not they perceived danger, for example. The other species did not demonstrate this, “suggesting that particular associations may be species-specific” Atrax robustus.
Australian scientists have spent decades studying funnel spiders, an endemic venomous species that is known for being the deadliest in the world. “They have the most complex venoms in the natural world, and are valued for the natural and therapeutic bioinsecticides that are potentially hidden in their venom molecules,†explains Dr Linda Hernandez, from the Australian Institute of Health and Tropical Medicine at James Cook University.
In their study, the researchers examined the venom produced by different funnel-web species under different conditions. To do this, the team collected four different funnel-web species: Border Ranges (Hadronyche valida), Darling Downs (Hadronyche infensa), Southern tree-dwelling (Hadronyche cerberea) and Sydney funnel-web (Atrax robustus), and subjected them to different tests, such as being pricked with tweezers.
“We mapped his behavior and measured his heart rate with a laser monitor to establish a proxy for his metabolic rate. Then we collect its venom and analyze it with a mass spectrometerâ€, explains Hernández.
Following the results, the researchers found that certain spiders had variations in their venom based on different factors, such as defensiveness and heart rate.
The most striking findings were in the Border Ranges species: “With the Border Ranges funnel net, the expression of some venom components was associated with heart rate and defensiveness. The other species did not demonstrate this, suggesting that the particular associations may be species-specific.”
In their conclusions, the authors say that these spiders may use different behavioral strategies to offset these costs: “Our results suggest that spiders may increase their metabolic rate when using poisons and reduce their movement when faced with a threat.”
In addition, they value their study, by demonstrating “for the first time how the specific components of the venom are associated with particular physiological and behavioral variables, demonstrating that these relationships depend on the context.”
