Breathe easy, inland taipan. Your ”most venomous snake” crown is safe. For now.
While some sources report the faint-banded or Belcher’s sea snake as the most toxic, it doesn’t even make the top 10 according to Encyclopaedia Britannica, the BBC or National Geographic. That’s not the only confusion about this incredibly rare Pacific sea snake.
As well as hanging about in no fewer than three different genera over the years – Atulia, Chitulia, and now Hydrophis – the faint-banded sea snake has had some of its original specimens tossed into other species entirely, namely the slender-necked (Hydrophis melanocephalus) and hook-nosed (Hydrophis/Enhydrina schistosa).
It’s been confused with the latter most recently, but luckily for us, hook-nosed anti-venom would work on both.
But why do some sources say it’s the most lethal?
I mentioned him in the inland taipan post, but Dr. Bryan Fry, or “David Attenborough on acid” in the reptile world, made a few forum posts to this effect.
When it comes to snake venom, we can rank its general horror using the Median Lethal Dose, or LD50, which means that of the animals injected with it, 50% of them died. The inland taipan has an LD50 of 0.025, so the lower the number, the more toxic the venom. However, how the venom was injected can make a difference.
According to Fry, the 1990s book “Snakes in Question: The Smithsonian Answer Book” didn’t take this into account, so the different LD50s were mixed up, making the faint-banded sea snake appear the most toxic.
Admittedly I’m terrible at analogies, but it would be a bit like saying the potato is the quickest-cooking vegetable, but neglecting to mention it was blasted in a microwave while the rest were oven-cooked.
What’s more, in their extremely helpful guide on sea snake bites, the Toxinology Department of the Women and Children’s Hospital of Adelaide advise that its effects are “unknown”, but probably dangerous due to other, similar species.
So both its name and its venom have been mixed up. But what is it really, and why the soft bottoms?
As an elapid, the faint-banded sea snake is actually related to cobras, and ripples about no deeper than 300 metres (984 feet) in the seas of South-East Asia and Oceania. As far as we know it gives live birth, has small fangs and eats fish and burrowing eels, and this is where a soft bottom comes in handy.
A sandy or muddy sea bed is a likely hiding place for prey, and what’s more, the faint-banded sea snake hunts by grabbing on with its fangs and chewing, waiting for the venom to do its work. The soft bottom of a fleeing quarry would therefore be welcomed. Once the venom’s done its work, the snake swallows its prey whole, so that might be another reason for the “belcher” in its name.
To help stay underwater, its tail has been flattened into a paddle, and like other members of its genus, the faint-banded sea snake has lungs the length of its entire body. If that wasn’t enough, according to Encyclopaedia Britannica, it can expel up to 90% of its CO2 waste and bring in 33% of its oxygen needs through its skin, so it can stay submerged for hours. It might not be as swish on land, though.
Equally, although its venom likely contains dangerous neurotoxins, the faint-banded sea snake’s bite probably wouldn’t hurt.
Due to its small fangs, it might bite you without you even knowing, and wouldn’t leave any impressive scars. It also wouldn’t be that interested in human flesh.
As Fry has pointed out, beyond the odd exception (looking at you, coastal taipan), sea snakes are usually docile and uninterested in scuba divers. Less than 3% of sea snake bites turn out to be fatal, although I guess being bitten, and the realisation of said bite, could both be heart-stopping after a couple of hours.
Perhaps even the snake isn’t sure of how dangerous it is, so its warning bands are just half-hearted.
Latin: Hydrophis belcheri
What? Lightly banded sea-snake, until recently assumed the most venomous in the world.
Where? Up to 300 metres / 984 feet deep over sandy sea bottoms in South East Asia and Oceania.
How big? About 80 cm / 31 inches long on average, but may grow to more than a metre / 39 inches long.
Endangered? Listed as Data Deficient by the IUCN, since it’s very elusive, rare, and we don’t know much about it.
Probable motto: I’m as shy as my bands.
They sound…interesting. Do they need my help at all?
Rasmussen et al. found evidence they were used for skins in Thailand and Vietnam, but this sea snake tends to avoid humans and isn’t considered commercially valuable – so it seems to be under the radar.
Just to prove I’m not fibbing:
Bland, Alastair. 2012. “Snakes: the good, the bad, and the deadly“. Smithsonian Magazine.
Editors of Encyclopaedia Britannica. No date. “Elapids“. Britannica.com.
Editors of Encyclopaedia Britannica. No date. “Sea snake“. Britannica.com.
Howard, Brian Clark. 2015. “What Happens When Two of Ocean’s Most Venomous Creatures Fight“. National Geographic.
“Hydrophis belcheri“. No date. WCH Clinical Toxicology Resources. University of Adelaide.
“Hydrophis belcheri (Gray, 1849)“. No date. Reptile Database.
“Is the Belcher’s sea snake the most venomous snake in the world?” 2018. Metafact.io.
Kharin, V.E. 2005. “Distribution of a Little-Known Sea Snake Chitulia belcheri (Gray, 1849) and New Records of Rare Species of the Genus Leioselasma Lacepede, 1804 (Serpentes: Hydrophiidae)“, Russian Journal of Marine Biology 31(3):159-163.
Mirtschin, Peter et al. 2017. “Australia’s dangerous snakes: identification, biology and envenoming“. CSIRO Publishing.
“Most venomous“. 2005. Venomdoc Forums.
Rafferty, John P. No date. “9 of the world’s deadliest snakes“. Britannica.com.
Rasmussen, A. No date. “Sea snakes“. FAO.
Rasmussen, A. & Sanders, K. 2010. “Hydrophis belcheri . The IUCN Red List of Threatened Species” 2010: e.T176751A7297371.
Rasmussen A. et al. 2011. “Marine Reptiles“, PLoS ONE 6(11): e27373.
Scott, Kellie. 2015. “Venom Doc Bryan Grieg Fry experiences 26 snake bites and 23 broken bones in the name of science“. ABC News.
Shukla, Priya. 2018. “Why fatal sea snake bites are unusual“. Forbes.
Sundstrom, Kathy, and McDonald, Bill. 2019. “Boy asks paramedics ‘am I going to die?’ after often-deadly sea snake bite on Sunshine Coast“. ABC News.
Takasaki, Chikahisa. 2009. “The Toxinology of Sea Snake Venoms“, Journal of Toxicology: Toxin Reviews, 17(3):361-372.
Featured image credit: © 2011 Rasmussen et al; Marine Reptiles. PLoS ONE 6(11): e27373. doi:10.1371/journal.pone.0027373