Hydrophis belcheri
Snake Facts And Behaviors

Belcher’s Sea Snake Species Profile (with Snake Bite and Venom Facts)

There are so many snake species in the world. That’s why we only hear about the largest snakes, or the ones with the biggest fangs, or the ones with the most potent venom. Belcher’s sea snake is commonly called the most venomous snake in the world, but is it true?

Belcher’s sea snake lives in the ocean around southeast Asia. They live almost all of their lives underwater. They’re erroneously referred to as the most venomous snake in the world, when they aren’t. That’s the Inland Taipan. That being said, their bite is still strong enough to kill you, although they’re timid and afraid of humans.

If you were to ever find one in the wild, you better hope that you have some antivenom handy. Their bite can kill in as little as half an hour, which makes it difficult to find help in time. As they say, though, knowledge is power—so let’s learn more about this snake.

Belcher’s Sea Snake Information

Belcher’s sea snake is a snake that lives in the ocean, from the moment they’re born until the moment they die. They’re common in southeast Asia, and live close to the short of most countries in the region.

You can find them all around Malaysia, Indonesia, the Philippines and on the south coast of Vietnam. Scientists aren’t sure of how big their population is, which is why they’re listed on the IUCD Red List as ‘Data Deficient,’ rather than vulnerable, endangered or of ‘least concern.’

Other Names for Belcher’s Sea Snake

Belcher’s sea snake was named after Sir Edward Belcher, a British naval officer, and explorer from the 1800s. The snake was first discovered by a botanist called John Edward Gray, another British man.

Gray was one of the most prolific zoologists of the era, and was responsible for identifying and naming more than 300 species of reptiles.

The snake was ‘rediscovered’ by Darwin not long after, although he withdrew his claim at being the first to find the snake when he found out that Gray had already found and named it.

Aside from their common name, they go by a few others. First, their scientific name is ‘Hydrophis belcheri.’ Hydrophis is the name for the family of sea snakes that live in the western and southern Pacific Ocean, whereas ‘belcheri’ obviously comes from ‘Belcher.’

Hydrophis, if you didn’t know, comes from ancient Greek. Hydro refers to water, and the suffix –ophis comes from the Greek word for snake. They’re also known as the faint-banded sea snake, which is a result of their pattern.

Because quite little is known about them and the other species that live near them, they’ve been confused with other snakes. Some people mistakenly call them the ‘hook-nosed sea snake.’

This is a more common sea snake that belongs to a different genus. They’re also mixed up with the ‘blue-banded sea snake,’ which belongs to the same genus but is a different color. Neither of these names is correct for Belcher’s sea snakes, though.

How to Identify the Belcher’s Sea Snake

Because they look like some other snakes—and have been called incorrect names in journals—the vast majority of online sources have incorrect pictures and descriptions of Belcher’s sea snake.

Faint-banded sea snake

In terms of appearance, Belcher’s sea snake isn’t very distinctive:

  • It’s covered from top to tail in low-contrast bands. It’s a dull yellow color with green bands across its back, from top to tail.
  • It’s a medium-sized snake, only reaching 40 inches maximum.
  • Its head is quite short and narrow too. This is unlike many other venomous snakes, which have large heads for their body (so that they can store lots of venom in their venom glands). Its head is the same color as the rest of its body.
  • Belcher’s sea snake has a flat tail, which it uses like a scuba diver’s flipper to paddle themselves along. This helps them move more quickly underwater. As a result, their tail isn’t much narrower than the rest of their body.

They’re often confused for other sea snakes, like the yellow-lipped sea krait or Hydrophis pachyceros. These snakes share similar habitats, and are of the same family.

The yellow-lipped sea krait has blue-green and black bands, as well as a yellow face. Their colors are much brighter than Belcher’s sea snake, and their bands wrap all the way around their body, whereas Belcher’s sea snake bands don’t.

Belcher’s Sea Snake Diet

They live their whole lives underwater. They’ll occasionally surface for air, because they don’t have gills. But apart from that, they live and hunt underwater. Their diet primarily consists of small fish, fish eggs, shellfish, eels and similar. No studies on what else they might eat have been done.

Because Belcher’s sea snake lives near the short, they primarily hunt in coral reefs and similar areas. They can’t move very fast, so they don’t chase their prey down.

Instead, they actively swim and hunt in areas with lots of crevices and enclosed spaces where their prey might hide. They find it much easier to catch prey there, because a fish out in the open could swim away from them—they’re much faster.

Belcher’s Sea Snake Habitat

Belcher’s sea snakes live in a ‘marine neritic’ habitat. This means that they live in the ocean, but not way out to sea. They stay in shallow areas around the coast.

That’s because, as we said, they can only hunt for prey in shallow water where it can’t get away as easily. They only live in southeast Asia—nowhere else in the world.

In that area of the world, shallow waters are often coral reefs. This part of the ocean is teeming with life, including tropical fish, regular fish, sea turtles, sharks and more.

It’s the perfect place for a predator like Belcher’s sea snake to live, because there is so much food and so many places for them to hunt.

Unfortunately, as most of us know, coral reefs are under threat from industrial chemicals and acids that are eroding the coral slowly but surely.

While no studies into the population of Belcher’s sea snake have been done, the negative human effect on coral reefs will no doubt take its toll. If the coral reefs disappear, Belcher’s sea snake and their favored prey will disappear too.

Predators That Eat Belcher’s Sea Snake

Data on what eats sea snakes, and Belcher’s sea snake, in particular, is scarce. There’s so much that we don’t know about this snake, simply because nobody has bothered to study it yet.

However, other sea snakes in similar habitats have many predators that probably feed on Belcher’s sea snake too. These include:

  • Birds of prey like sea eagles. Bald eagles are an example of a sea eagle, although these don’t live in the sea snake’s natural habitat. White-bellied sea eagles and the grey-headed fish eagle do, though, and feed on sea snakes regularly.
  • There are plenty of sharks that live in coastal regions around Australia and southeast Asia. These include the grey reef shark and the blacktip reef shark, which live and hunt around the coasts of Australis, Indonesia, Malaysia, and Borneo.
  • Big fish aside from sharks. Big fish like swordfish live in the area. Swordfish and similar large, predatory fish can reach 10 feet long. They’re more than big enough to eat a sea snake. The same goes for very large eels.

Predators find it much easier to eat a young or injured Belcher’s sea snake than a fully able adult. Sea snakes are ovoviviparous, which means that they don’t lay eggs.

They keep the eggs inside them until they hatch, at which the young are born live. The point is that parent sea snakes don’t look after the young after it’s born, so they make easy prey, even though they’re born with venom. They’re too small to defend themselves from large predators like these.

How Deadly Is Belcher’s Sea Snake?

The first thing you should know is that Belcher’s sea snake is quite timid. It would much rather try and get away from you, than seek you out and attack you. On the other hand, when they do bite, their venom is extremely toxic.

Figuring out which is the ‘world’s most deadly snake’ is complicated. That’s because there are many factors you have to think of. First, the toxicity of the venom has to be taken into account.

Belcher's Sea Snake Bite Facts

But aside from that, there are other things you have to calculate too:

  • The amount of venom that the snake uses per bite
  • The amount of people the snake kills in the real world, not just hypothetically
  • How fast acting the venom is
  • Whether there’s an antivenom that you can use
  • How aggressive the snake is, i.e., how likely it is to bite you
  • Whether it envenomates (uses venom) every time it strikes, or not
  • Whether the snake can inject the venom intravenously, i.e., in the vein itself, or not. If it can, the venom is much more fast-acting and therefore deadly

Belcher’s sea snake is incredibly deadly. Its venom is very toxic indeed. And because it’s a sea snake, it can attack you when you least suspect it.

However, it’s quite a short snake, and it’s afraid of humans. It’ll only strike when it feels like it has no other choice, because somebody has been threatening it.

Belcher’s Sea Snake Toxicity

In terms of toxicity, Belcher’s sea snake isn’t number one in the world. When you look up the snake online, so many sites claim that its venom is the deadliest, drop for drop. But that’s just not the case.

The confusion arose from a book that got confused about a concept called LD50. This is the scientific term which means the ‘median lethal dose.’

In short, the median lethal dose is the amount of something that you have to inject for it to kill 50% of people injected (or mice, or rabbits, or anything).

Snake venom toxicity is measured in LD50. However, the exact method of testing can differ. For example, you can either inject it into the muscle or directly into the bloodstream.

If you inject it straight into the bloodstream, it takes less venom to kill somebody. The author of a popular book got their figures confused, and compared the intravenous LD50 study on Belcher’s sea snake with intramuscular LD50 studies for other snakes.

Belcher’s sea snake venom is still incredibly deadly. There have only been one or two studies on Belcher’s sea snake, so scientists aren’t exactly sure how toxic it is. It seems to have an LD50 of about 0.25mg/kg, which would make it one of the deadliest snakes, if not the deadliest altogether.

The only problem is that they produce hardly any venom. They’re such a small snake compared to, say, the inland taipan or the black mamba. They only produce a fraction of the amount of venom that these other snakes do.

According to a paper in the journal Toxicon, scientists had trouble extracting any venom from them because they produced so little.

Belcher’s Sea Snake Fangs

Belcher’s sea snake only has a tiny mouth. It’s already quite a short and thin snake, but its mouth is even proportionally small for its size. This means that its fangs are actually quite short and small too.

Sea snakes have what are called ‘proteroglyphous’ fangs. This means that their fangs are quite short, and can’t be folded back into the mouth (like a rattlesnake’s fangs can). They’re like short hypodermic needles.

When they catch prey, they’ll hold onto it and not let go until it’s fully envenomated. This is different to rattlesnakes and other common venomous U.S. snakes, which bite once and then let go.

They’ll then hunt after the prey, waiting until it becomes uncoordinated and close to death. Belcher’s sea snakes progressively envenomate their prey by holding on. This is why most bites to humans aren’t using the full amount of venom possible.

Fortunately, because their fangs are so small, this makes it quite difficult for them to bite us. First, somebody diving in the ocean is usually wearing a scuba suit of some kind. This is hard for them to get their fangs into.

Belcher's Sea Snake venom facts

Besides that, because their jaws are quite small, they can’t easily bite a leg or an arm. That’s because they can’t open their mouth wide enough. By contrast, they could easily bite something like a finger, which is just the right size.

Belcher’s Sea Snake Venom Effects

Immediately after the snake bites you, you’re unlikely to experience any symptoms. That’s partly because you’re underwater. The cool water around you makes it a little more difficult for your skin to pick up on the sensation of being bitten, so you might not even notice at first. However, once it gets going, it’s deadly. Belcher sea snake venom contains postsynaptic neurotoxins.

While not much is known specifically about Belcher sea snake venom, postsynaptic neurotoxins all have a similar effect. The venom attacks the nervous system, which stops your body from being able to operate normally.

It prevents your nerves from being able to communicate with your body. Your brain is sending signals to your body all the time, whether it’s to do something you want your hands or arms to do (like writing or waving) or something that your body does without you thinking (like breathing).

When you’re injected with neurotoxins, they stop the nerves from being able to communicate the brain’s signals to the rest of your body.

This begins to have effects, such as:

  • You start slurring your words
  • You can’t quite keep your balance
  • You start to get confused
  • You feel nauseous

What’s happened is that the venom has gotten into your bloodstream. From there, it starts to bind to the receptors next to your nerves, which are what collect the information from the nerve that was sent by the brain. The venom accumulates on these receptors and stops them from working.

It gradually gets worse and worse, until:

  • You can’t breathe properly
  • Your heart starts beating erratically, or even stops completely (cardiac arrest)
  • You can’t think straight, and may even have a seizure before becoming unconscious

Even though we don’t think about it, the brain still has to send signals to the heart and lungs to tell them what to do, and when. If the brain can’t do that because the receptors for the nerves are blocked, the heart and lungs stop working.

Sea snake venom can cause this to happen within half an hour. Again, very little research into Belcher sea snake venom has been done. However, we know that it has these effects because all the snakes in the same family have the same effects.

How Many Deaths Does It Cause?

If Belcher’s sea snake were to bite you, you’d die if you didn’t have any antivenom around. It takes around thirty minutes from the time that you’re bitten, until you die.

Fortunately, as we’ve already said, the snake is quite good-tempered. It’s unlikely to attack unless you’ve done something to provoke it, like catch it in a fishing net and haul it in.

Not only that, but they live in the sea, which limits the amount of contact they have with people. The only people who come across them are fisherman and people swimming in the ocean.

While that’s not to say that nobody ever finds them in the wild, it occurs much less often than if the snake lives in the undergrowth, or in trees, like common U.S. snakes.

Regarding numbers, it’s very rare that anybody dies from a sea snake bite. Aside from Belcher’s sea snake, there are a total of 70 known sea snake species. But even if you count every single species, it’s still very rare for anybody to be bitten and killed by one. Australia, for example, is surrounded by sea snakes on all sides.

But even there, according to the BBC, there’s only been one recorded death. That man was a fisherman working on a trawler, and the exact species of sea snake wasn’t identified.

Can You Survive a Sea Snake Bite?

Yes, you can survive a sea snake bite. Antivenoms have been created for most common venomous snake bites, and Belcher’s sea snake antivenom is available.

It’s manufactured by a biotech company called CSL Limited in Australia (antivenom code MAuCSL03). This antivenom works for all sea snakes in the same family around Australia and southeast Asia.

The only caveat is that if you’re out at sea and you’re bitten by one, it will be quite challenging to survive. That’s because the venom is so fast-acting, it can take little more than half an hour to kill you. If you don’t happen to have some antivenom already, it might be hard to source some in that time.

The good news is that Belcher’s sea snake doesn’t always envenomate when it bites. This means that it doesn’t always use its venom. It only seems to use venom about a quarter of the time.