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dangerous animals in japan

Most Dangerous Animals in Japan: 7 Species to Look Out For

Japan is an island country best known for its cherry blossoms, cutting-edge technology, experimental cuisine, and cultural values. However, nestled in the Pacific Ocean in far eastern Asia, you might be wondering, are there any dangerous animals in Japan?

Japan sprawls from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the South. Across its less than 400,000 square kilometers are some of the most varied landscapes in the world from volcanoes and waterfalls to deep valleys and bamboo forests. With so many climates, it’s no surprise that a host of unique creatures live and thrive in Japan, but some can be deadly.  

Our guide gives you the rundown on everything you need to know about the most dangerous animals in Japan so that you can keep safe on your next trip. Let’s get into it. 

Bears

brown bear in japan

We probably don’t need to explain why bears are such feared animals, and you’ll find a few species in Japan. Bears are carnivorous mammals belonging to the Ursidae family. They’re actually classified as caniforms or doglike carnivorans, and they’re closely related to the household canine, along with wolves, foxes, and raccoons. 

Bears are extraordinarily intelligent and have the largest and most complex brains compared to all other land mammals of their size. They’re generally gentle and tolerant animals, and mother bears are known for being affectionate, protective, and devoted providers, but if you get on their wrong side, it won’t end well.

Brown and black bears live in Japan. The Ussuri brown bear, also known as the Ezo brown bear, is native to Hokkaido in northern Japan and is considered the most ferocious of Japan’s grizzly mammals. The Ussuri brown bear is one of the largest and strongest bears, close to the Kodiak bear (the world’s largest) in size, weighing between 880-1,210 lb and reaching heights of six to nine feet. 

This species was responsible for Japan’s deadliest bear attack in 1915 where seven people were killed by one brown bear over five days after the animal awoke from hibernation and attacked several homes in Sankebetsu. Although this was an isolated incident, around 1-2 people are killed every year by bears in Japan while 10 to 20 are injured in attacks. 

It’s not uncommon for attacks to happen when people are collecting wild bamboo shoots in the spring, which the bears are also fans of. Around 90 to 150 brown bears are left in the West Ishikari Region of Hokkaido, and 80 to 135 in the Teshio-Mashike mountains, but Asian black bears are distributed throughout Honshu and the Shikoku Islands and they have a reputation for being extremely aggressive toward humans with just as many attacks recorded annually. 

If you’re headed into the mountains in any of Japan’s bear territory, be loud and even wear a bell to make your presence known and scare off any dangerous mammals. If you see a bear, back away or move sideways slowly, so you can keep an eye on the bear. Don’t make eye contact or run—bears can run as fast a racehorses. 

If the bear follows you, stop and hold your ground or try to scare the bear by making a loud noise. If you are attacked, drop to the ground and protect your head and neck. Be sure to never leave garbage or food around in any wilderness, especially if you’re camping out, and don’t go off-trail if it can be avoided. 

Snakes

wild snake
Photo by Anna_OM/Envato Elements

Snakes are some of the deadliest animals in the world and the most venomous to humans, with some serpents harboring enough poison to kill 100 adult people. Japan is home to a host of different snake species, many of which are virtually harmless, but there are a few that you want to look out for. 

There are three majorly venomous snakes in Japan, including the mamushi, a Russian and Japanese pit viper, the yamakagashi, a tiger keel-back snake, and the most formidable of all, the habu, Okinawan’s highly toxic yellow-spotted pit viper. The venom of the Okinawan habu has cytotoxin and hemorrhaging components. This means it destroys red blood cells, has a necrotizing effect on tissue, and carries a higher risk of infection.   

Common symptoms include nausea, vomiting, hypotension, and possible death. Luckily, the fatality rate is less than one percent but encounters with this snake still aren’t pleasant for the 50 people who get bitten every year. An antidote is widely available in Japan, but the habu’s venom can still cause permanent damage to its victims. 

If you are bitten, avoid tourniquets and pressure dressings which can worsen the effects seeing as the venom is hemotoxic. Keep the wound above the heart if possible and get to a hospital as quickly as you can. 

Habus are only found on a small group of islands in Japan, namely the Ryukyu Archipelago including Okinawa and Amami. They favor forest, grassland, shrubland, and coastal habitats and can also be found on rock walls, in old tombs and caves, as well in urban areas—so keep those doors shut. The habu is slender with a larger head that is covered in scale. They’re olive or brown in color with elongated dark blotches that sometimes have yellow spots or yellow edges. 

Murder hornets

murder hornet
Photo by Studo_OMG/Envato Elements

If the name wasn’t enough to scare you off, their six-millimeter stinger might do the job. Murder hornets, or Japanese giant hornets, can be found all over Asia, and even in some parts of the US, but they’re native to temperate and tropical Japan and are the largest wasp on the globe. 

Murder hornets usually reach lengths of around 4-5 cm but can have a wingspan of around 8 cm. They can travel at speeds of 40 km/hour and are common in rural areas of Japan where they nest in trees from May to September. 

If you encounter a singular murder hornet, it’s still best to steer clear although their poisonous stinger could be harmless in small doses. However, if you’re stung multiple times, you can expect excruciating pain and even death, which is more likely if you experience a swarm. 

Murder hornets are aggressive and easily agitated. If you come across a nest, there’s a chance that a group of hornets could orchestrate a concentrated attack where they chase and sting you. With smooth stingers, they’ll be able to attack multiple times without causing harm to themselves and such an ambush could prove fatal.  

Hornets are responsible for around 220,000 emergency department visits every year and 60 deaths worldwide. It’s thought that murder hornets are responsible for around 30 to 50 of these in Japan alone, although most fatalities are a result of anaphylactic reactions. 

Make use of protective screens in your home or holiday rental in Japan to keep hornets out. If you think you’ve come across a nest, contact the local authorities and don’t approach it yourself. Try not to panic or run if you see a hornet mid-flight. If stung, clean the wound immediately and seek medical attention if symptoms like pain, itching, swelling, and redness spread rapidly from the affected area, or if you experience breathing problems or dizziness. 

Redback spiders

redback spider

Although not endemic to Japan, redback spiders were first spotted in Osaka in 1995 and since then, populations have spread rapidly. This dangerous arachnid is now fairly established across the country. Redbacks are thought to have arrived in cargo shipments of wood chips from Australia and have surprisingly adapted to survive the harsh Japanese winters. 

Redbacks are a close relative of the black widow spider but they boast a red dorsal stripe as well as the hourglass underside pattern that it shares with the notorious black widow. They’re also indigenous to Oceania but have achieved significant distribution throughout Southeast Asia. 

Redbacks aren’t particularly aggressive and prefer to avoid humans, but they are venomous and most bites happen when the spider is disturbed or dislodged. The female redback spider is one of the most poisonous in Japan, and although unlikely to cause deadly envenomation with no fatalities recorded in the country as of yet, a bite will cause intense localized pain which is likely to increase, as well as possible nausea, vomiting, sweating, and abdominal pain. 

If symptoms persist for more than 24 hours, or the pain spreads beyond the local site, it’s a good idea to seek immediate medical attention. We recommend getting any suspected spider bite checked out and properly cleaned as spider bites are prone to infection. 

Female redback spiders grow to around 15 mm in length, while males are even smaller at just 5 mm. Both are black or dark brown in color with bulbous abdomens, but the males lack the distinctive red stripe and also aren’t capable of causing any harm to humans since their fangs are too small to penetrate skin. Like black widows, redback females are also known for their sexual cannibalism, meaning they have been known to consume their male counterparts after reproduction.  

Ticks

removing a tick

They may look harmless, but these minuscule critters are one of the deadliest on our list due to the diseases they can spread. Ticks attach themselves to wild animals and household pets, but when they find a human host, they can infect them with just about anything they’ve picked up along the way, including lethal viruses like Lyme disease. 

One of the 46 different species of tick that are present in Japan is the Asian long-horned tick, which is often transferred from wild and farmed deer to human hosts. These ticks have been known to carry some Japan-borne diseases like the novel Yezo virus and Japanese spotted fever which can prove fatal if left untreated. Around 180 cases of spotted fever and 10 case of Lyme disease are observed annually in Japan, with the main suspect for the spread of such diseases being ticks.

Not only do these inconspicuous insects spread disease undetected, but they can continue to suck your blood for hours or even days after attaching to your skin. The wound left from a tick bite can easily get infected and should be cleaned and cared for properly. You should also monitor victims of tick bites carefully for symptoms of a contracted disease. Fever and diarrhea are especially important to look out for and are even more of a cause for concern in Japan’s elderly population. 

Be sure to wear long sleeves and pants whenever walking in rural areas and use insect repellent as frequently as possible. After any walk in the countryside or through tick-infection regions, check yourself and your pets for ticks. You also shouldn’t just pry the tick off it is already latched into the skin. Instead, use clean tweezers to grasp the tip as close to the skin’s surface as possible. Once you have a good grip on the tick, use upwards with even pressure to make sure the whole head is removed along with the body. 

Leaving the head doesn’t increase the risk of tick-borne diseases but it does increase the risk of infection. Once removed, don’t touch the tick or crush it in your fingers. Put the tick in alcohol, place it in a sealed bag/container or wrap it in tape before flushing it down the toilet to effectively destroy it. 

Viper box jellyfish

box jellyfish
Jelly fish tank

The Chironex Yamaguchi or habu-kurage, meaning “viper jellyfish” when translated from Japanese, is a species of box jellyfish found in Japan’s coastal waters. Box jellyfish are the most venomous marine animal and are sometimes deemed to be the most venomous living thing in the world with tentacles full of harpoon-like stingers that can inflict a world of pain if you so much as brush past them. 

There are over 50 species of box jellyfish and they are found in warm waters all around the world but the most lethal varieties live in the Indo-Pacific and off northern Australia. The viper jellyfish is highly dangerous and has caused several deaths in Japanese waters. Their populations are most rife between July and September.  

Box jellyfish are also formidable predators and not as docile as one might think. They actively hunt prey, which varies from crustaceans and worms to small fish and other jellyfish, and they can swim at speeds of around five miles an hour. Box jellyfish don’t seek out humans, but with long tentacles of up to ten feet, they can deliver several painful lesions to swimmers before they have a chance to get away.

The 5,000 stinging cells per tentacle are triggered by animal and human skin and designed to stun prey or predator to prevent damage to the jellyfish. The toxin in the stingers attacks the skin, nervous system, and heart. The excruciating pain causes a victim to go into instant shock, which is made even more dangerous by jellyfish being exclusively coastal since victims can easily drown before being able to reach the shore or seek help. 

Box jellyfish stings can be survived but instant medical care is required and if you’re swimming far offshore, the likelihood of getting adequate help is low. Multiple stings often prove fatal since the nervous system and heart can’t tolerate the shock of the pain. Try to swim close to the shore if you’re taking a dip in Japan—box jellyfish favor deeper water. Also, be sure to wear a wetsuit or protective clothing when deep-sea diving as well as protective footwear.

Jellyfish can still sting out of the water and even after death, so stay away from any that are washed up on the shore too.   

Pufferfish

pufferfish

You’ve probably only seen them in cartoons, but pufferfish are a very real phenomenon. They’re best known for their ability to inflate into a ball shape to evade danger and even poison predators with their toxic spikes. Still, their poisonous nature has also garnered them quite the reputation, although it isn’t only in the seas of Japan and the northwest Pacific that you’ll have to worry about these curious swimmers.

Pufferfish are most deadly to humans when eaten. This might seem easy to avoid, but what makes them even scarier to visitors of Japan, is that they’re actually a delicacy in many parts of the country despite the paralyzing toxin that their bodies contain. 

Tetrodotoxin is present in the liver, gonads, intestines, and skin of a pufferfish. Unless the fish is cleaned and prepared by expertly trained chefs to remove all of the organs that contain the poison, then the meat of the fish will be contaminated when served. Pufferfish meat is called fugu and it is often served in high-end sushi restaurants in regions like Obama, Fukui in central Japan.

Fugu chefs are highly trained and must carry a license that takes around four to six years to acquire in order to prepare and sell fugu to the public. If fugu is sliced incorrectly and ingested, then the tetrodotoxin can cause the human body to become instantly paralyzed leading to asphyxiation and eventual death. 

There is currently no antidote available anywhere in the world, and the only treatment involves having the stomach pumped followed by a presumably long stint in the hospital. Some 50 people suffer fugu poisoning in Japan every year, and one or two succumb to the poison.   

Of course, you don’t have to try pufferfish when you’re in Japan and this is a good way to avoid any danger. However, if you’re keen to tick fugu off your bucket list, make sure you go to a certified restaurant or only try the flesh of pufferfish that is reared poison-free. Don’t take your chances with unreliable sources. 

You should also avoid pufferfish when swimming in the sea. Their spines carry tetrodotoxin which can enter the bloodstream if you come in contact with them. Even smooth puffer fish carry the toxin on their skin and you should never handle a puffer fish with bare hands. 

What is Japan’s deadliest animal?

Although bears are one of the most formidable predatory mammals in Japan with great strength and sharp claws, murder hornets are actually more deadly with a sting that can be lethal even to those who aren’t allergic, causing 30 to 50 deaths a year. 

Are there wild cats in Japan?

There are two wild cats that are native to Japan. These include the Tsushima leopard cat and the Iriomote cat, both of which live in the Okinawa prefecture along with many of Japan’s other exotic wildlife. However, these small wild cats pose little threat to humans and tend to avoid danger wherever possible. As endangered species, humans pose much more of a threat to Japan’s wild cats.  

Are there sharks in Japan?

Out of the 400 identified species of shark in the world, around a third (124 species) have been observed in Japan’s waters. Japan is long and narrow and spans a range of latitudes, so the types of sharks that roam the seas are varied. You’ll find mainly coastal sharks of temperate zones but there are also oceanic species and bottom-living sharks. There have been 27 attacks in Japan since 1862, 15 of which were fatal.