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Are sea snakes more venomous than land snakes?
- federicosocean
- Apr 7
- 4 min read
Updated: 5 days ago
Sea snakes are a type of snake that spends the majority of his time living in a marine environment. Although, certain species may spend some time in land or tide pools, they are dependent on the ocean for survival.
These snakes have acquired a worldwide reputation for being extremely venomous. Some journalistic sources point to the fact that some sea snakes are even more venomous than their land-based counterparts. But is that truly the case?
This is the question I'm going to try to answer in a complete and scientifically-accurate manner. Without further due, let's go!
Distribution and Habitat
Sea snakes are primarily found across the tropical waters of the Indian and Pacific Oceans.
In those regions, especially in Australia, the presence of other highly venomous animals is very well documented. Those dangerous animals are present both at sea, like with the blue ring octopus, or on land, with several species of venomous snakes and spiders.
There are also environmental factors that could give you a clue about why they have such a potent venom.
The sea is notoriously more difficult for venomous predators to catch prey.
First of all, venom can get more easily diluted on water so it has to be very potent to be effective even when dilution occurs.
But also, a prey can more easily escape a predator in water as it is a three dimensional space. Therefore, even if the venom was effective at killing the prey, it may still be too far for the predator to recover it.
However, I believe that the most impactful fact regarding their venom is that they are not only close to other venomous animals geographically but they are also related genetically to other extremely venomous australasian snakes. Examples include the death adders, brown snakes or even taipans.
Knowing, that the eastern brown snake and the inland taipan, are respectively second and first, in the ranking of the most venomous land snakes in the world, it is no wonder that sea snakes have such powerful venom.
Behavior towards humans
Although there may be variations in species and individuals, sea snakes are generally considered to be quite mellow when it comes to their behavior towards humans. Sea snakes are generally reluctant to bite and their handling is quite common by fishermen when they become trapped in fishing nets.
However, it is important to note that their behavior on land can be more aggressive as they feel less safe moving in this environment than their terrestrial counterparts.
Even if they are reluctant to bite, when they do, they often don't inject venom. Cases of venomous bites are incredibly rare. In 2018, a trawler fisherman was killed in Australia due to a sea snake bite. However, it was the country's second-ever fatality caused by a sea snake bite and the previous occurrence happened in 1935, more than 80 years prior. Despite all of this,, it is quite recommended to avoid the unnecessary handling of those snakes as a single venomous bite could mean a death sentence.
Is their venom the most potent of all ?
As said at the beginning of this article, some journalistic sources claim that the sea snakes have the most potent venom of all snakes.
It is very important to consider the species we are talking about. Even when taking into account the most venomous species of sea snake, the Dubois' sea snake, is ranked third in the world for venom potency.
The inland taipan and the eastern brown snake, all coming from Australia, dominate the first and second of the podium respectively for all snakes, land or sea.
Those results were found by measuring the LD50, which is the dose that kills half of the test population. It is measured in milligrams per kilogram (to compare the results for subjects with different weight)
According to a paper published by the University of Queensland, the LD 50 through subcutaneous injection of the inland taipan is 0.025 mg/kg, the eastern brown is 0.0365 mg/kg and the Dubois' sea snake is 0.044 mg/kg.
As we said before, sea snakes are related to australasian snakes, such as the ones mentioned above.
Therefore, what we can confidently say is that sea snakes are generally more venomous than most terrestrial snakes.
Especially knowing that a lot of terrestrial snake species have no venom such as constrictor snakes like pythons or boas. But also, the variety of land snake species have venom that is not medically significant.
Conclusion
I think that we can wrap up this article by stating something very clearly.
Sea snakes are not more dangerous than land snakes.
First of all, their behavior is for the most part much less unpredictable than a lot of land snakes.
They are often very reluctant to bite and when they do, they rarely inject venom. Let's just take a land snake we mentioned a lot in this article : the eastern brown snake.
This species is often very aggressive and has a tendency to break into homes to find shelter. For this very reason as well as for its venom, it is the snake responsible for the most snakebite deaths in Australia annually.
But also, their venom, despite its potency, is still lagging behind the most venomous snakes on the planet.
All this article shall not be taken as an invitation to handle sea snakes or even worse, keep them as pets.
But I think it can serve as a reality check for people who are afraid of exploring the ocean due to fear of sea animals, like sea snakes.
Just keep in mind that if you encounter a sea snake, just take a time to admire (from a distance) this beautiful animal, leave it in peace and everything will be perfectly fine.
I hope you truly enjoyed this article and that you learned at least one thing, just like I did when researching it.
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See you on the next one!
Federico Zein
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