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7 Most Dangerous Snakes In Japan To Know About

Man holding a dangerous Japanese rat snake in his hand
Photo by twenty20photos from Envato Elements

Japan is an island nation in the northwest Pacific Ocean with an incredibly diverse ecosystem and one of the wildest in Asia. There are five main islands, along with thousands of smaller coastlines, all with rugged and mountainous terrain. These rocky hillsides are perfect territory for the 47 snake species found across Japan, some of which are dangerous snakes and should be avoided at all costs.

Snakes thrive in Japan’s humid climate and feed on the vast array of amphibians, rodents, and small mammals found in the wildlife. But are there any venomous snakes in Japan you need to know about? Quite simply, yes. There are several venomous and dangerous snakes in Japan that any traveler should be aware of and cautious to approach.

Snake bites remain a devastating and life-threatening environmental hazard across tropical nations. Between 2017 and 2018, there were 1,670 hospitalizations in Japan due to snake bites. Most of these incidents were caused by the most dangerous and venomous snake in Japan, the Mamushi.

Japanese Mamushi

snake basking in sunlight in grass
Photo by perutskyy from Envato Elements

Latin Name: Gloydius blomhoffii

The Japanese Mamushi is the most venomous snake in Japan. Every year, 2,000-3,000 people are bitten by this snake. Recovery typically takes around 1 week and may require hospitalization and severe reactions may even require intensive care. Approximately 10 people die each year from a Mamushi snake bite in Japan.

These snakes are typically 45–81 cm in length, with the longest known Mamushi in Japan measuring 91 cm. The normal pattern and coloring are a pale gray, reddish-brown, or yellow-brown background, overlaid with a series of irregularly-shaped lateral blotches. This coloring is perfect and allows the snakes to lay low in leaf piles to then ambush unexpecting prey. Mamushi’s can be found across a range of terrain including swamps, marshes, meadows, open woodland, and rocky hillsides.

The Mamushi venom is a potent neurotoxin and contains an anticoagulant. There is an effective antivenom available that is made in both Japan and China.

Habu

snake on wood stump closeup
Photo by ivankmit from Envato Elements

Latin Name: Protobothrops flavoviridis

Habu snakes are a venomous pitviper species found in the Ryukyu Islands, a chain of islands stretching down towards Taiwan. These snakes average a whopping total length of 4–5 feet (120–150 cm). However, the longest known Habu snake was recorded at a staggering 7.9 feet (240 cm).

Considering the length of the Habu, they are fairly slender-looking snakes with gracefully proportioned large heads. Typically, these snakes are light olive or brown ground color and are patterned with elongated dark green or brownish blotches.

They have extremely potent venom that contains cytotoxin and hemorrhaging components. A bite from a habu snake can cause nausea, vomiting, hypotension, and possibly death. Despite the strength though, fatalities are only 1% of the snake bites recorded.

Japanese Tiger Keelback

grass snake basking in sunlight
Photo by perutskyy from Envato Elements

Latin Name: Rhabdophis tigrinus

The Japanese Tiger Keelback, also commonly known as the Japanese Grass Snake, is an endemic species in Asia and is one of the smaller snakes found across Japan. It is also poisonous, getting its toxin primarily from eating poisonous toads. Therefore, there is no knowing how toxic each individual snake is.

Unlike other species in the serpent world, the tiger keelbacks use their toxin mostly for defense against predators, rather than for hunting prey. The toad toxin is stored in a gland located at the back of the snake’s jaw and is sprayed at any attacking predators. In many circumstances, the keelbacks choose to flee rather than fight, highlighting the timid nature of this potentially venomous snake.

So, although this snake is venomous, very few deaths have been recorded due to its tendency to display defensive behavior as opposed to aggression and striking. You can easily miss this snake in the wild and undergrowth as it typically grows to a maximum total length of 44 cm. Colors vary from light olive green to reddish-brown, and some have small blackish spots.

Tsushima Island Pit Viper

Mountain Pit Viper, wild snake moving through water and leaf litter
Photo by ckstockphoto from Envato Elements

Latin Name: Gloydius tsushimaensis

The Tsushima Island Pit Viper is one of many Japanese pit viper species found across the nation. As the name suggests, this species is found on Tsushima Island of the Japanese archipelago situated in-between the Tsushima Strait and Korea Strait.

The entire island is covered in forests with very few plains. This is the most perfect terrain for the Tsushima island pit viper to lurk under leaf litter, ideal to hunt frogs and other small animals.

Similar to other vipers, this dangerous snake has long fangs designed for penetration and administration of the venom. Besides the fact of this being a venomous snake, little else is known about this reclusive and deadly species.

Oriental Odd-Tooth Snake

A pale brown snake on a rustic log and black background
Photo by twenty20photos from Envato Elements

Latin Name: Lycodon orientalis

Oriental Odd-Tooth Snakes are an endemic venomous species found across most of Japan.

This snake hunts from the forest floor in the night, using leaf litter as cover to ambush unsuspecting amphibians and rodents. The length of this snake varies between 30–70 cm and has black stripes with a lighter colored underside.

Despite its wide coverage of Japan, the Oriental odd tooth snake is an endangered species. Encounters with this rare snake species are extremely uncommon.

Japanese Rat Snake

Dark colored rat snake with head slightly raised
Photo by twenty20photos from Envato Elements

Latin Name: Elaphe climacophora

The Japanese rat snake is big but not considered not too dangerous. This is the most commonly encountered snake species found in Japan and it often reaches lengths of up to 3.5 meters. Another common name some regions of Japan use is the Aodaisho rat snake.

In Iwakuni City, Yamaguchi Prefecture is the only place in the world where there is an entirely natural population of albino rat snakes – a pure white snake with pink eyes.

As the name suggests, the main diet of this large Japanese nonvenomous snake consists of rats and other small rodents along with frogs and lizards. They can be found throughout the forestry and mountainous spaces, but are sometimes known to venture into domestic houses. While it may be alarming to encounter one of these larger snakes, they generally do not pose a major threat to humans and are even favored by farmers for rat population control measures.

Sea Snakes In Japan

A black banded sea snake moving across a sandy beach
Photo by Jeremy Bezanger on Unsplash

The coral reefs and warm south Pacific waters surrounding the many Japanese islands are perfect for sea snakes. Sea snakes are some of the most venomous snakes on the planet and are often feared by locals across the South East Asia region. Typically, these snakes are very docile and do their best to avoid human encounters. They have small mouths with fangs right at the back of the jaw, meaning being bitten by a sea snake is highly unlikely.

Local legend often says that the only way for sea snakes to bite a human is in between the fingers or toes. That being said, you should still give these snakes a wide berth when diving or swimming. Sea snakes are extremely venomous.

Japan has several species of sea snakes in the surrounding waters, to name a few:

  • Annulated sea snake, Hydrophis cyanocinctus
  • Black-headed sea snake, Hydrophis melanocephalus
  • Ornate reef sea snake, Hydrophis ornatus
  • Ryukyu ornate sea snake, H. o. maresinensis
  • Short sea snake, Hydrophis curtus
  • Stokes’s sea snake, Hydrophis stokesii
  • Viperine sea snake, Hydrophis viperinus
  • Yellow-bellied sea snake, Hydrophis platurus

If bitten by a sea snake, you should seek urgent medical attention. Initially, there probably won’t be any pain. After a few hours, the neurotoxin will start to display reactive symptoms including painful muscles, paralysis, and blurry vision. If no symptoms appear after eight hours then the sea snake probably didn’t inject any venom.

Summary: Dangerous Snakes In Japan

Black Mangrove Pit Viper Snake Purpureomaculatus on a Tree
Photo by ethangabito from Envato Elements

Of all the widely distributed snake species found in Japan, encountering venomous snakes in Japan is a possibility, especially if you plan on exploring the wilder areas of mainland Japan and the islands. While some pack a potent and lethal venom in their bite, most will only attack when threatened as a final defensive move.

If you are unfortunate to experience a bite from one of the dangerous snakes in Japan, regardless of the species, you should seek medical attention urgently. Try to take note of what the snake looked like so medical professionals can administer the correct antivenom if required.

Are there any poisonous snakes in Japan?

Japan has over 40 species of snakes across the mainland and islands, some of which are venomous. The four most poisonous and dangerous snakes in Japan are the Japanese Mamushi, Japanese Tiger Keelback, Habu, and sea snakes. A bite from any of these snakes will cause neurological issues and potential burning pain at the bite wound.

Are there any cobras in Japan?

Japan does not have any cobras on the mainland or islands. The same goes for neighboring Korea. However, cobras are endemic to the Southeast Asian and Indian continents. Cobras can be found in India, Bangladesh, Burma, Bhutan, Cambodia, Nepal, China, Philippines, Malaysia, Laos, Singapore, and Vietnam.

What is the largest snake in Japan?

Japan’s largest snake on record is a 3 meter Habu and is one of the most dangerous snakes in Japan if cornered or threatened. These snakes normally average between 1.5 and 2 meters in length. Luckily, the most dangerous snake in Japan, the Mamushi, rarely grows over 1 meter. However, the smaller size does not mean it is any less dangerous.