The funnel-web spider is the most venomous spider in the world, capable of killing a human with a single bite.
However, its venom is not always the same.
A new study has revealed that the venom of some funnel-web species varies depending on the circumstances they face, which could have implications for their potential use in medicine and biotechnology.
The study, published in the journal PLOS ONE , was led by Dr. Linda Hernández Duran from James Cook University's Australian Institute of Tropical Health and Medicine.
She and her team collected four different species of funnel-web --the Border Ranges (Hadronyche valida), Darling Downs, (Hadronyche infensa), Southern tree-dwelling (Hadronyche cerberea) and Sydney funnel-web (Atrax robustus) -- and exposed them to different stimuli, such as being touched with tweezers and blown with air.
They then measured their behavior, heart rate and venom composition using various techniques.
They found that some species had different venom components associated with different factors, such as defensiveness and heart rate.
How wing shape affects venom production
PERDIANSYAH/AFP via Getty Images
One of the factors that may influence how funnel-web spiders produce their venom is their wing shape.
Spiders have wings, or at least structures that resemble wings. These are called book lungs, and they are used for breathing and gas exchange, as per Phys.org.
They are located on the underside of the spider's abdomen, and they have a folded structure that resembles the pages of a book.
The shape and size of the book lungs affect the flight ability and dispersal capacity of spiders, which in turn determines how well they can move across different habitats and cope with environmental changes.
The book lung index (BLI) is a measure of book lung elongation that reflects the dispersal ability of spiders.
The higher the BLI, the more elongated the book lung and the better the spider can fly across gaps between habitat patches.
The study showed that there is a global gradient in dispersal ability among spider species, from low near the equator to high at higher latitudes.
This gradient is related to the variability of climate across regions. Spiders at low latitudes live in more stable climates and therefore tend to have lower BLI and lower dispersal ability.
They are also more sedentary and territorial, often defending their territories all year round.
Spiders at higher latitudes live in more variable climates and therefore tend to have higher BLI and higher dispersal ability.
They are also more migratory and nomadic, often moving to track seasonal changes in resources.
The study also showed that the sensitivity of spider species to habitat fragmentation varies by latitude, with tropical spiders being more vulnerable than temperate spiders, as per PNAS.
This is because tropical spiders have lower BLI and lower dispersal ability, which makes them less able to cope with habitat loss and isolation.
They also have higher specialization and endemism, which means they have more specific habitat requirements and are found only in certain regions.
The study suggests that conservation policies need to take into account the role of climate in determining the dispersal ability and sensitivity of spider species to habitat fragmentation.
It also implies that habitat corridors or stepping stones are needed to increase connectivity and allow species to move across fragmented landscapes, especially in the tropics where most of the forest biodiversity is concentrated.
The study also highlights the link between behavior, physiology, and venom composition in funnel-web spiders.
It shows that some venom components are associated with particular behavioral and physiological variables and that these relationships are context-dependent.
This means that the venom of funnel-web spiders is not a fixed entity, but rather a dynamic one that changes according to the situation.
Funnel-web spider venoms contain thousands of unique peptides that have diverse biological activities, such as blocking pain receptors, inhibiting blood clotting, or killing bacteria.
Some of these peptides could be used as therapeutics or natural bioinsecticides, but their discovery and development require a better understanding of how they are produced and regulated by spiders.
By revealing how funnel-web spider venoms vary depending on circumstances, this study provides valuable insights for further exploration and understanding of the ecological role of venom and its applications for human health.
