Episode 196 -Yellow-Bellied Sea Snake: Made for the Sea

“…and today we’re talking about a reptile who’s lady is the sea. But more on that later.”

We all know and share a healthy fear of snakes. They live under rocks and slither on their bellies to get around. But there are actually dozens of snake species that don’t live on land at all. Instead, they’ve taken to the sea, and many of them never grace the ground. The Yellow-bellied sea snake rides the waves all over the world. Despite their name, they are no cowards. They’re the most widely distributed snake species in the world. Adapting your body and habits to take the world by storm is the sea snake’s way in Life, Death, and Taxonomy.

Description of the Sea Snake

  • Medium-length snakes with a dark brown back and a bright yellow belly spanning its entire body length(counter-shaded like many oceanic animals)
  • The snake’s body is flattened like an eel’s in order to move through the water better than your typical terrestrial snake and there’s a short ridge that extends along the belly that acts as a kind of keel
  • Its tail is flat and paddle-shaped so that it can swim and change directions easily in the water.
  • The tail shape and the keel make it pretty tough for the snake to move around on land
  • The tail is a very light yellow with black cow spots
  • Its head is long and thin like a garden snake rather than the wide triangular heads of vipers
  • Some forms are entirely yellow

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro!

  1. Magnificent frigate
  2. Satanic nightjar
  3. Little bustard
  4. Tiny-sky tyrant


  • Females are slightly longer at 88 cm (35 in).
  • How many Yellow-Bellied Sea Snakes go into their typical max dive depth?
  • Hint: Sea snakes are often observed on ocean drift lines, which are ribbons of floating seaweed, debris, and driftwood. These driftlines can stretch for miles and act as a natural meeting place for pelagic animals. 
  • 56.8 sea snakes. 50 m (164 feet).


  • 47 grams
  • How many Yellow-Bellied Sea Snakes go into the heaviest pumpkin ever recorded?
  • Hint: The pumpkin was grown by Mathias Willemijns, in October 2016 in Germany. This record had been beaten five times in as many years before it was solidified by Mathias. 
  • 25,329.5 sea snakes. The pumpkin was 1,190.49 kg (2,624.6 lb).

Fast Facts about the Sea Snake

  • Range: Basically along most of the coasts of the Indian and Pacific Oceans near the equator. All along the east coast of Africa and the islands there in the Indian Ocean. From Djibouti to South Africa. Then all throughout Southeast Asia, Australia, the Koreas, and even all the way over to the West Coast of North and Central America. They like warm waters close to land. It’s one of the most widely-distributed snakes in the world and is the only sea snake around Hawaii.
    • It has been seen in the Atlantic, but that’s not considered its native range.
    • It’s easy for large ships to pull in sea snakes in their ballast and take them across the globe.
  • Diet:
    • They eat small reef and open-water fish.
    • They like to float on the surface of the water pretending to be floating seaweed. Fish come up to find food or shelter and are treated to an unhealthy dose of neurotoxins
    • Sea snake venom is particularly bad and will quickly cause paralysis, respiratory depression, and kidney failure – three things you really don’t want to happen when you’re swimming in the ocean.
    • Fishermen are the most common human victims. They report that the initial bite is practically painless, so they often don’t know they’ve been bitten until they start feeling dizziness, difficulty swallowing, nausea, weakness, shortness of breath etc. It can even land you in a coma.
    • It has very low LD50 levels – meaning that it takes very little to lead to death in 50% of instances in a controlled animal test.
  • Behavior:
    • Sea snakes live their whole lives in the ocean, but they need to drink fresh water to survive like any snake. 
    • Initially, researchers thought that the salt gland in its head allowed it to filter salt from the surrounding water, but now they know that the snake actually just drinks rainwater that collects on the surface of the ocean. Although saltwater is less dense than fresh water, and should sink and be mixed with the salt, there is a brief period after rain where there is a brackish “lens” of water on the surface. If the salinity is low enough, the snakes can drink.
    • It can go for up to 7 months without fresh water
  • It can dive for long periods of time and actually absorb oxygen through its skin rather than having to hold its breath.

Major Fact: Made for the Sea

The Yellow-bellied sea snake is a genuine ocean reptile. It’s a true sea snake, which means that it will not leave the water willingly and it’s totally adapted to life at sea. 

One of its most obvious aquatic adaptations is it’s body shape. Sea snakes have flat bodies like an eel. Their body tapers to a keel like a boat, to help with aquadynamics. 

On most snakes, ventral scales on their bellies are the largest scales. But ventral scales are comparably small on sea snakes because of this tapered keel. 

But it gets more interesting when you look at what’s underneath the surface. 

The first oddity is their lungs. Unlike eels, sea snakes do not have gills and have to return to the surface to breathe. But they spend as much as 90% of the time underwater. How do they do this?

The average snake has a pair of lungs that runs from their neck to halfway down their body. Sea snake lungs are much longer, running almost the full length of their bodies. 

Most sea snakes can hold their breath for up to 30 minutes. But true sea snakes like our friend the yellow-belly can last for longer. They may last as much as 90 minutes underwater.

We used to think that sea snakes didn’t need to drink fresh water, but that’s not true at all. But where do they get fresh water in the ocean? On the ocean, of course. 

That’s right. On the ocean. Precipitation gathers on the surface of the ocean, and sea snakes are apparently able to drink the precipitation like someone who only likes the heads of beer. When there isn’t any ocean dew, they can survive without water for about three months

Ending: So go with the currents, tour the world’s oceans, and don’t drink saltwater like the yellow-bellied sea snake here in Life, Death, and Taxonomy.