Why Venomous Sea Snakes Are Suddenly Invading California

Yellow-bellied sea snake washed up on the beach
© John Fader/Shutterstock.com

Written by Kyle Glatz

Updated: August 23, 2022

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When most people imagine snakes, they think of them slithering along a forest floor or sidewinding through the sand. However, a lot of these reptiles spend a significant portion of their lives in the ocean, and many species of them are venomous. In fact, some of the most venomous snakes in the world live in the sea. For better or worse, most sea snakes only live in the Indian and Pacific Oceans and are rarely encountered off the coast of the United States. However, these venomous sea snakes are suddenly invading California’s coastline.

Today, we’re going to take a closer look at the situation. We’ll show you where these serpents usually live, why their range is changing, and what to do if you encounter one.

What Are Sea Snakes?

The Olive sea snake has special valves in its nose to keep water out while its swimming.

Most sea snakes are docile and avoid humans.


As their name suggests, sea snakes are snakes that live in the ocean. More than 60 species of these reptiles exist. They come from Elapidae, the cobra family. Some of them are true sea snakes that come from the subfamily Hydrophiinae. Others are sea kraits from the subfamily Laticaudinae that evolved from Asian cobras. The kraits are semiaquatic and spend a lot of their time on land.

The aspect of these creatures that frightens most people is their venom. After all, some of them have incredibly potent venom, like Belcher’s sea snake, also called the faint-banded sea snake, along with Dubois’ sea snake. The latter has the most powerful venom of all water serpents.

These creatures often have a relatively small home range. They especially inhabit reefs where food is plentiful rather than in the open ocean. However, some sea snakes are more mobile than others. The yellow-bellied sea snake is perhaps the most well-traveled one of them all.

This snake has a range that includes all of eastern Africa, the SEA region, Australia, and even the west coast of the Americas, from California in the United States to Peru.

What Is the Normal Range for Sea Snakes?

Sea Snake

Most of these underwater reptiles live near reefs instead of traveling the open ocean.

©Tomas Kotouc/Shutterstock.com

The vast majority of sea snakes are found in the warm coastal waters of the Indian Ocean and the Pacific Ocean. More specifically, these venomous creatures are found off the southern and eastern coasts of Africa, the southern portions of the Middle East and the Indian Subcontinent, South East Asia, and Australia.

Furthermore, the snakes also live in the warm equatorial waters stretching east from Papua New Guinea to Hawaii.

However, the vast majority of these snakes live by reefs near land instead of in the open ocean. One of the few exceptions is the yellow-bellied sea snake, and that is the snake that has traveled farthest east.

As we’ve said, yellow-bellied sea snakes live both near shores and out in the deep ocean. These snakes are a common sight because they live near the water’s surface. Also, they can travel quite a bit, and their flattened tail helps propel them through the water.

Overall, the range of these snakes is growing larger, and that is a concern to some people. After all, these are deadly creatures.

Can Sea Snakes Kill Human Beings?

Cat Snake Bite with Human Hand

Bites from these snakes are serious yet rare.

©Mufti Adi Utomo/Shutterstock.com

Yes, sea snakes can kill human beings. These creatures have very deadly venom that rivals or exceeds that of the most dangerous terrestrial snakes. Only a few land snakes are deadlier in terms of venom potency.

Around 3% of all sea snake bites are fatal. While that is certainly an alarming fact, only a few types of serpents are responsible for these bites. In particular, the hook-nosed snake and the beaked sea snake make up a large portion of these fatal attacks.

Fortunately, many sea snakes are not as aggressive as they are curious. They usually try to stay away from humans in most cases. Yet, they may approach humans, and these interactions can lead to bites. However, not every bite contains venom.

Another benefit for humans in the case of venomous sea snake bites is the morphology of these snakes. These reptiles tend to have smaller fangs and an overall lower venom output than others. That means they might have trouble penetrating through swimming attire or equipment and into flesh. Even if they do, the amount of venom they introduce is small and may not be fatal. Still, these are animals to be avoided.  

Why Venomous Sea Snakes Are Invading California?

Dog Park Series - San Diego Header

Sea snakes prefer to live in warm waters.

©Sherry V Smith/Shutterstock.com

Sea snakes are coming to California in greater numbers due to rising ocean temperatures. As we’ve said before, sea snakes prefer to live in areas with warm waters. As the average ocean temperatures have continued to rise throughout the world, sea snakes have started to expand their range.

This effect is especially pronounced throughout the years when El Niño, a climate pattern, is dominant. During El Niño, the water on the west coast of the United States warms up, bringing larger numbers of tropical creatures to the shores, including sea snakes.

In short, climate change has enticed the pelagic yellow-bellied sea snake to swim farther than ever before. This is the sea snake with the largest range, the only one to reach Hawaii. This snake has washed up on California beaches a few times since the first incident in 1972, and it has always happened during El Niño.

With increasingly warmer temperatures on the horizon, sea snake sightings will probably become more common in the future.

What Should You Do If You Find a Sea Snake?

Yellow-bellied Sea Snake

Even if you see this snake on the beach, it’s wise to just leave it alone because it will defend itself.

©Ken Griffiths/Shutterstock.com

If you find a sea snake on the beach or in the water, you should leave it alone. Treat it like any other venomous creature, and you can avoid being harmed.

When you see one of the yellow-bellied sea snakes on the beach, that usually means it’s ill or too weak to get back out to the ocean. For the most part, these reptiles are docile when encountered in the water. That doesn’t mean they’re not dangerous or that it’s a good idea for you to handle them.

Keep a wide berth, do not handle them, and report any sightings to local authorities and wildlife control. If you get bitten by one of these snakes, then you need to seek medical attention right away.

While these snakes have small mouths and rarely bite humans, their venom is potent, and you need to get help right away. The vast majority of the time, you won’t encounter these snakes in the U.S.; even then, they’re usually avoidable.

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About the Author

Kyle Glatz is a writer at A-Z-Animals where his primary focus is on geography and mammals. Kyle has been writing for researching and writing about animals and numerous other topics for 10 years, and he holds a Bachelor's Degree in English and Education from Rowan University. A resident of New Jersey, Kyle enjoys reading, writing, and playing video games.

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