by Dr. Anand Titus and Geeta N. Pereira
The World Health Organization (WHO) estimates that about 5 million snakebites occur each year, resulting in up to 2.7 million envenoming’s. Published reports suggest that between 81,000 and 138,000 deaths occur each year. Snakebite envenoming causes as many as 400,000 amputations and other permanent disabilities. In India, around 90% of snakebites are caused by the ‘big four’ among the crawlers – common krait, Indian cobra, Russell’s viper and saw scaled viper. Effective interventions involving education and antivenom provision would reduce snakebite deaths in India. However, there’s a twist to the tale. In the world of snakes, where venom is often seen as a formidable weapon for hunting and defense, there exists a curious phenomenon known as the “dry bite.” Unlike their venomous strikes, which can be lethal or incapacitating, a dry bite occurs when a snake delivers a defensive or warning bite without injecting venom into its target. This intriguing behavior challenges conventional notions of snake aggression and underscores the complexity of their interactions with prey and potential threats. About 50% of snakebite cases can be dry bites. They are characterized by fang and tooth marks and the absence of injected venom. Dry bites can occur from all snakes, but their frequency varies from species to species.
Understanding the mechanisms and significance of dry bites offers valuable insights into snake behavior, venom utilization, and the delicate balance between survival strategies and ecological dynamics in snake habitats.
The phenomenon of dry bites holds profound evolutionary significance, reflecting the adaptive strategies that snakes have developed to optimize their survival and reproduction.
Understanding Dry Bite
A dry bite is a term used to describe a snake bite where little to no venom is injected into the victim. While it might seem puzzling that a snake would choose not to deliver venom during a bite, several factors contribute to this behavior. Firstly, snakes primarily use venom for subduing prey and defending against threats. In cases where the snake perceives the target as non-threatening or the bite is defensive rather than predatory, it may opt for a dry bite to conserve venom for future use. Unlike envenomation bites, which can have severe consequences, dry bites typically result in minimal or no symptoms beyond the physical trauma caused by the bite itself.
One key factor influencing venom delivery is the snake’s intent. Snakes typically reserve venom for subduing prey or defending against threats, and they may choose to deliver a dry bite if the target is perceived as non-threatening or if the bite is defensive rather than predatory. This selective venom use allows snakes to conserve their venom for critical situations, ensuring their survival in their natural habitat
How to Identify markings of a venomous and Nonvenomous Snakes
The presence of one or two puncture wounds left by a fang or set of fangs can similarly indicate a bite from a venomous snake, as these marks will often be distinct from those left by non-venomous snakes, which tend to consist of multiple smaller puncture wounds arranged in a semi-circle.
Can we distinguish between Dry and Wet bite
It can, however, be difficult to determine whether a bite is ‘dry’ or ‘wet’, as a bite from any animal will often cause inflammation and swelling. This may complicate clinical diagnosis, making it more challenging to decide early on whether or not a snakebite victim needs antivenom.
Causes of Dry Bite
Several factors can influence whether a snake delivers a dry bite. One factor is the snake’s intent. If the snake is in a defensive posture rather than actively hunting, it may deliver a dry bite as a warning to deter potential threats without expending valuable venom.
Furthermore, the physiological state of the snake, including its age, health, and reproductive status, can affect venom production and delivery. Younger snakes or those in poor health may have less control over their venom output, increasing the likelihood of a dry bite. Additionally, environmental factors such as temperature, humidity, and prey availability can influence venom production and the snake’s motivation to deliver venom during a bite.
Adults are thought to be far more judicious than juveniles and will therefore more often deliver a dry bite if they perceive that they are under threat, which usually provides them with enough time to escape. This intentional decision to conserve venom can occur in one of two ways:
1. Assessment of Encounter: The snake evaluates the encounter with the target and consciously chooses not to activate the extrinsic venom gland musculature. This decision-making process allows the snake to gauge the level of threat and respond accordingly, opting for a dry bite as a means of defense while conserving venom for more critical situations.
2. Venom Metering: Alternatively, the snake may activate the venom gland musculature but at a level insufficient for venom expulsion. This controlled release of venom, known as venom metering, allows the snake to regulate the amount of venom delivered during a bite. By metering venom, the snake optimizes energy-related or ecological factors, conserving resources while still deterring potential threats effectively.
While adults exhibit this strategic venom conservation behavior, neonates and juvenile snakes typically lack the ability to control venom metering and often empty their venom glands during bites. This age-related difference in behavior underscores the importance of experience and learning in snake behavior, with adults demonstrating a higher degree of behavioral sophistication in response to perceived threats.
Signs and Symptoms
One needs to understand the signs and symptoms of dry bites to differentiate them from envenomation bites. While envenomation bites typically result in rapid onset of symptoms such as pain, swelling, and tissue damage, dry bites may cause minimal or no symptoms beyond the physical effects of the bite, such as puncture wounds or bruising.
Implications of Dry Bite
Dry bites have significant implications for both the snake and the victim. For the snake, delivering a dry bite allows it to conserve venom for hunting and self-defense, ensuring its survival in its natural habitat.
Dry bites represent a strategic trade-off for snakes, allowing them to conserve venom resources while still effectively deterring potential threats. By selectively using venom only when necessary, snakes can minimize the energetic costs associated with venom production and maximize their chances of survival and reproductive success. Furthermore, the ability to deliver dry bites may have facilitated the diversification of snake species, enabling them to exploit a wide range of ecological niches and prey types.
Management of Dry Bites
Efficient management of dry bites requires a multifaceted approach encompassing various aspects of prevention, diagnosis, and treatment. First-aid measures, including wound cleaning and immobilization, are crucial for minimizing the risk of secondary infections and complications. Healthcare professionals must be trained to differentiate between dry bites and true envenomation to avoid unnecessary antivenom administration. Furthermore, public education campaigns aimed at promoting awareness of snakebite risks and appropriate response measures can empower individuals to take proactive steps to prevent snake encounters and mitigate the consequences of bites.
Ecological and Evolutionary Significance
Dry bites offer insights into the complex interactions between snakes and their environment, highlighting the adaptive strategies that snakes have evolved to optimize their survival and reproduction. By selectively using venom only, when necessary, snakes can conserve energy and resources while still effectively deterring potential threats.
Research and Conservation
Further research on dry bites is essential for advancing our understanding of snake behavior, ecology, and evolution. Additionally, understanding dry bites can inform conservation efforts aimed at protecting snake populations and mitigating the risks of snakebite incidents in human-dominated landscapes.
Conclusion
Dry bites in snakes serve as a captivating aspect of snake biology, shedding light on the nuanced interactions between these reptiles and their surroundings. By unravelling the mysteries behind dry bites, scientists and conservationists can better understand and appreciate the intricacies of snake ecology while promoting coexistence between humans and these fascinating creatures.
Dry bites have significant implications for human-snake interactions and snakebite management strategies. Recognizing the prevalence of dry bites and the factors influencing their occurrence can inform public education efforts aimed at reducing snakebite incidents and minimizing unnecessary fear or hostility towards snakes. Additionally, understanding the circumstances under which snakes may deliver dry bites can help healthcare professionals make informed decisions about the appropriate treatment and management of snakebite victims. While dry bites offer some relief from the immediate danger of envenomation, they still warrant caution and proper management to ensure the well-being of both snakes and humans.
References
Anand T Pereira and Geeta N Pereira. 2009. Shade Grown Ecofriendly Indian Coffee. Volume-1.
Current Knowledge on Snake Dry Bites