The country has some of the deadliest snakes in the world and most snakes in Australia have venom that interferes with blood clotting. Since ancient times, scientists have been aware of the fact that snakebites induced by such species as the Eastern Brown Snake (Pseudonaja textilis) and the taipan (Oxyuranus species) can lead to a potentially fatal disease (venom-induced consumption coagulopathy or VICC). This syndrome quickly wears out clotting factors in the body, and blood loses the ability to clot.
Another study released recently in Toxins (2025) provides a fresh insight into the evolutionary and clinical implications of such venoms.
Comparing the effects of various snake venoms on animal and human blood, scientists made some interesting observations of the evolutionary divergence of venom use, and of what it suggests as to the treatment of snakebite victims.
How Snake Venoms Hijack Clotting
The venoms of Australian elapid snakes attack the blood clotting cascade. They do so frequently as biochemical hacks, transforming clotting factors such as Factor VII, prothrombin, etc. into their active form. This generates a cascade of uncontrolled clotting, the opposite effect of inoculating the blood since after the clotting proteins have been ingested the blood becomes incoagulable.
The research established that there were two primary venom mechanisms:
FXa-only venoms: These are based on the hijacking of the Factor Va of the victim.
FXa:FVa venoms: These have a full venom prothrombinase complex which is independent of host factors.
The two mechanisms are both lethal, although the rate and consistency of the clotting differs significantly among species of snakes.
Evolutionary Drivers: Prey-Specific Venom
Snake venom did not develop to protect humans, but to catch prey. To analyse prey-specific variations, the research team tested venoms in amphibian, bird, rodent and human plasma.
The venoms of specialist species, such as the Red Bellied Black Snake (Pseudechis porphyriacus), had become optimized to paralyze amphibians and reptiles. In the blood of mammals their venom was slower.
Generalist species, whose meals included a very diverse diet, exhibited a general venom activity with all plasma types.
This diet-dependent specialization is an example of how evolution determines venom strength. Frog eating or reptile eating snakes can substitute a generalized venom power with accuracy when hunting ectothermic organisms.
A Tale of Two Brown Snakes
The Eastern Brown Snake (Pseudonaja textilis) is one of the snakes in Australia that has a terrible reputation, but its discovery of a snake in the water was the most surprising. Scientists have found that there is a profound geographic division in the role of venom:
Northern (Queensland) populations Venom produced rapid weak clots.
Southern populations (South Australia) Venom was strong, clotted, stable and taipan-like in appearance.
This implies that the southern brown snakes returned to an ancestral venom trait, which forms strong clots instead of weak ones. These evolutionary reversals are uncommon and demonstrate the adaptive plasticity of venom systems.
Why It Matters for Humans
These distinctions are of critical clinical importance. VICC can occur within minutes in victims bitten by snakes whose venom contains weak clots which rapidly disintegrate to cause incoagulable blood. Conversely, snake bites that contain clotting venoms of high strength may initially exhibit firmer clotting prior to a decrease in clotting factors.
This variation can:
Make diagnosis complicated: Coagulation tests can appear variously depending on the population of snakes in the area.
Affect treatment: Antivenoms do not necessarily work equally with all types of venom. Indicatively, antivenoms that are developed with venom of northern P. textilis may not be effective against southern populations.
Delay recognition: Stratification of case reports by geography may cause physicians to underestimate severity.
Antivenom and Therapeutic Problems
Antivenoms are specific to counteract the lethal toxins of snake venom, but their success is determined by the extent to which they bind the venom proteins. The study warns that:
Snakes raised in one area may not be fully effective as antivenoms against snakes of another region.
Certain specialist venoms, such as those of frog-eating snakes, might not be well neutralised by existing broad-spectrum antivenoms.
Snakes that are very similar, such as taipans and brown snakes, are sufficiently different that their ability to cross-neutralize might be poor.
This substantiates the necessity of regionally aware antivenom production and clinically more accurate clinical research.
Key Takeaways
Venoms adapt with prey: Specialist snakes adapt their venoms to particular prey, and generalists have general-purpose toxins.
Even within a single species such as the Eastern Brown Snake, intraspecific variation is important: The venom can vary radically between regions.
Clinical management should be adjusted: Doctors need to look at geography when diagnosing and treating snakebite victims.
Antivenom development should be dynamic: Existing formulations may never be able to counter all variants of venom, and additional research is essential.
Conclusion
One of the most amazing evolutionary tools in nature is snake venom, lethal, versatile and in constant flux in response to environmental challenges. This work shows that among members of the same species, the divergence of venom can be dramatic, redefining evolutionary biology and medical practice.
To Australians who coexist with some of the most toxic snakes in the world, the findings are a reminder of the importance of timely medical care and the continued development of antivenom. And to the scientists, the study finds that the study of venom through the lens of ecology and medicine can help us understand not only the evolution of life but also the struggle to preserve it.
Reference:
Morecroft H., Zdenek C.N., Chowdhury A., Dunstan N., Hay C., Fry B.G. (2025). X Marks the Clot: Evolutionary and Clinical Implications of Divergences in Procoagulant Australian Elapid Snake Venoms. Toxins, 17(417). https://doi.org/10.3390/toxins17080417