Are There Snakes In The Ocean?

Are There Snakes In The Ocean?

When scoping out a new home or picking the perfect camping site, there is one thing that always seems to send people running in fear: Snakes.

There are over 3,000 species of snakes that have been identified worldwide. They populate everywhere except the far North (Iceland, Greenland), Antarctica, Ireland, and New Zealand.

Although these reptiles are relatively prolific and commonly feared, only about 200 (or 7%) could seriously harm or kill a human being.

So why are people so afraid? Well, perhaps the absence of limbs paired with a flicking tongue and a loud hiss can be a bit menacing.

If you do have a fear of these scaley critters, where can you go to get away?

Are There Snakes In The Ocean?

While the majority of snake species live on land, there are, in fact, around 70 kinds that live in the world’s oceans. If we divide the oceans into the four most basic seas (Arctic, Atlantic, Pacific, and Indian), snakes live in only 2 of them.

Because these ‘sea snakes‘ thrive in warm, tropical waters, they can be found in areas of both the Pacific and Indian Oceans.

While the West coast of the United States borders the warm Pacific waters, Hawaii is the only US state where a sea snake has been spotted (outside a few isolated sightings of a Yellow-Bellied Sea Snake washed up to the California coast by El Nino currents) in its natural habitat.

The snakes that populate these coastal and reef environments fall into two genus categories. Hydrophiinae is a family known as ‘true’ sea snakes.

These snakes are closely related to certain Australian species like the Coral snakes and the Taipan. While species within Hydrophiinae are strictly aquatic, the other genus (Laticaudinae) is known to be semi-aquatic.

This family is commonly referred to as Sea Kraits and is more closely related to Asian cobras like the Indian or King cobra.

Because sea snakes and kraits do not like cool or polar waters, there are no known species in the Atlantic or Arctic Oceans.

They also avoid areas of high salinity, such as the Red Sea. When in the water, most sea snakes and kraits can be found within the top 100 ft.

Like the 15 that are found off Australia’s coast, many species prefer the shelter of coral reefs and Mangrove islands.

For sea kraits, the shallow waters allow them to move from the water to the land to hunt and mate.

Scientists have observed these animals (particularly the Yellow-Bellied Sea Snake) moving further north along the coasts of Western Europe and Mexico.

They believe this is, at least in part, due to global warming. As the waters of the Atlantic grow warmer, this tropical species may be found in fishing lines where it has never been seen before.

What Is the Difference Between a Sea Snake and a Krait?

As I mentioned above, the snakes that live in our oceans have been divided into two categories: Sea Snakes and Sea Krait.

While their differences are minimal, it is important to understand that Kraits spend some time on land. They lay their eggs on shore, and the hatchlings, much like sea turtles, make their way to the water.

In contrast, Sea Snakes spend their entire lives in the ocean and incubate their eggs internally before giving birth. Many sea snakes and krait species look very similar to the snakes we see slithering about on land.

They are long and slender with a round or pointed nose and thin tails. Unlike terrestrial (or land) snakes, sea snakes have special adaptions that help them to swim.

Both Sea snakes and Kraits have a more slender, ribbon-shaped body and tail that helps to propel them through the water.

This feature sometimes causes them to be confused with eels upon first glance, but there is one easy way to tell them apart: eels have a dorsal fin, and snakes do not.

Another important adaption is that these aquatic creatures have nose holes that are situated on the top of their head instead of on the side like many land snakes.

This allows for easier breathing when the snakes break through the waves. Because, unlike fish, snakes do not have gills. They must resurface for air.

Some species must resurface every 30 minutes, while others can last almost 8 hours! How is this possible?

One of the most important features of a sea snake or krait is its extremely long lungs. These snakes have lungs that stretch nearly the length of their entire body.

Species of sea snakes and kraits averagely reach between 4 and 5 ft in length, but species, such as the Yellow Sea Snake, can reach up to 10 ft.

Banded Sea Krait Swimming in Solomon Islands
Banded Sea Krait Swimming in Solomon Islands

Besides being able to hold their breath for an incredible amount of time, some of these snakes can get even breath through their skin! Land-dwelling snakes do not easily do this due to their tightly woven scales.

Through a process called Cutaneous Respiration (which is extremely common for amphibians like frogs), some sea snakes can obtain as much as 33% of their needed oxygen.

This process also allows them to remove over 90% of the carbon dioxide they need to expel. This process becomes extremely important when the snakes have to dive for prey.

Some sea snakes have been known to dive over 800 ft in search of prey. As they dive, their blood is moved away from their lungs and into the capillaries in the skin, making their skin more effective for respiration than their lungs.

A study conducted on the Blue-Banded Sea Snake concluded that the snake even has an area within its head that acts as a canal for water to reach the snake’s brain.

Another difference between these swimming serpents and their land-dwelling counterparts is that sea snakes and kraits have scales that do not overlap.

The underbelly of terrestrial snakes is covered with a type of scaley shell called a scute. 

This structure helps them to grip the earth as they move along because sea snakes do not have a scute. They are unable to move back into the water when beached.

Because, as I stated above, Kraits are semi-aquatic, some species do have scute-like features and scales. This allows them to move seamlessly from water to land.

Are Sea Snakes and Kraits Dangerous?

Of the 70 species of sea snakes and krait, roughly 50 are known to be highly venomous. One of the most common is the Banded Sea Krait.

This species is said to have 10 times as potent venom like that of a rattlesnake. Banded Sea Snakes are most commonly spotted off the coast of New Guinea, Japan, Sri Lanka, and the Philippines, usually by local fishermen who catch them in their nets.

While each Banded Sea Krait can produce up to 15 mg of venom, only a handful of lethal bites are on record.

The venom of these snakes often contains a powerful neurotoxin that attacks the muscular and nervous systems.

Because many species of these snakes are extremely docile (unless threatened or distressed), bites on humans are very rare.

Some more aggressive species include the Olive Sea Snake, Beaked Sea Snake, and the Ornate Reef Sea Snake. As with any venomous animal, it is best to give them their space if you come upon one.

These mild-tempered animals will usually only bite when they feel threatened, so avoid roughly grabbing or chasing them.

Suppose a bite does occur. It’s often a ‘dry’ bite or without venom. This is due to the fact that most snakes primarily use venom to subdue prey and less for defense.

These snakes are so docile, in fact, that on some Pacific coasts, fishermen handle them bare-handed. In many of the areas where these snakes can be found, hospitals will be sure to carry an antivenom for emergency use.

Other Ocean Critters That Look Like Snakes?

Imagine you were on vacation last month in Cali and swore you saw a sea snake; while this is a very small possibility, many other sea creatures can look a lot like these snakes.

One of the most common animals that people confuse with a sea snake or krait is the eel. Eels and snakes are very similar in their long, slender bodies.

RELATED: Do People Eat Eels?

Remember that sea snakes will look much like a swimming rope, whereas eels resemble a floating ribbon.

Eels also have a dorsal fin. Both animals have scales, but those of the snakes are much larger and easier to see; the scales of an eel are very small and make the animal appear smooth.

Another animal you might encounter on the reefs of the Pacific Ocean is the Synapta maculata or the Snake Sea Cucumber.

These sluggish creatures can reach up to 10 ft in length and could be confused with a hunting sea snake or krait.

One important distinction is that these cucumbers have 15 small tentacles. They also commonly have a brown or gray appearance, without bands or stripes like the snakes.

Are There Snakes In The Ocean?
Are There Snakes In The Ocean?
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Adrian Volenik

I've lived around animals my whole life and I hold a Diploma in Animal Physiology. When I'm not reading or writing about wild animals, health and fitness, and technology, you can find me playing with my son and two cats. My pastimes include running, playing video games, and solving the NY Times crossword.