The Mamushi (Gloydius Blmhoffii), also known as Japanese Mamushi or Japanese Pit Viper, is a venomous snake of the Viperidae family.

It is the most venomous species in Japan. Every year, between 2.000 and 3.000 people are bitten by this reptile.

Currently, 3 subspecies are recognized.


The body of the Mamushi is massive and ends with a small tail. Its head is triangular and flattened, which makes it distinguishable from its neck. Its eyes are of medium size with vertical elliptical pupils. Between its eyes and nostrils are located its thermoreceptors, small sensors that detect temperature variations.

Its main color is gray, brown, red or yellow. It is covered with a pattern of spots. The latter are often clear and bordered with black.

Its fangs are located on the front part of its jaw. They are mobile and fold back when his mouth is closed.

Mamushi Size

The Mamushi is a small snake. Indeed, it measures on average only 1.5ft (45cm). The largest recorded specimen was 3ft (91cm).

Its average weight is around 2.12 oz (60gr).

Its lifespan is 13 years on average.


The Mamushi is an animal mostly active at night. However, it is also possible to see it active during the coolest days.

Although it is considered as a terrestrial animal, it is also a very good climber. Indeed, it is often found on top of trees, especially when hunting.

To hunt, it uses the ambush technique. Thanks to its color which allows it to be easily camouflaged in the scenery, it hides in the vegetation and waits for a prey to approach it. To detect a warm-blooded prey, it uses mainly its thermosensitive dimples.

This snake has a rather aggressive temperament, especially when it feels threatened. Indeed, it does not hesitate to bite its opponent several times to defend itself.


The Mamushi’s venom is moderately toxic. It is composed of hemotoxins, two neurotoxins, as well as anticoagulants.

In one bite, it can inject up to 15mg, which remains relatively low.


Local symptoms associated with a bite of Gloydius Blmhoffii include pain, swelling, blistering, bruising, and sometimes necrosis.

Systemic symptoms are:

  • Abdominal and muscle pain
  • Nausea and vomiting
  • Diarrhea
  • Headaches
  • Bleeding
  • Visual disturbances
  • Paralysis
  • Convulsion
  • Renal insufficiency

If the bite is not treated, death can occur due to severe kidney damage.

Each year, between 10 and 50 people die from a bite of this reptile.

Bite Treatment

If you are bitten by this snake, it is essential to go to the hospital.

While waiting for medical help, here are some tips to limit envenomation:

  • Remove any accessory that could compress the bitten limb (bracelets, rings …)
  • Use a bandage to immobilize the limb and limit the lymphatic circulation. Be careful not to make a tourniquet because you don’t want to stop the blood circulation.
  • Do not take painkillers.
  • Do not apply any cream or ointment on the wound.
  • Do not incise the wound or suck out the venom with your mouth.

Currently, there are two antivenoms for Mamushi poison. Depending on the severity of the envenomation, several doses may be necessary.


The Mamushi is a species native to Japan.

Over time, this reptile has adapted to many different habitats. It can be found in grasslands, forests, rocky areas and wet pastures.

What do Mamushis eat ?

The diet of the Japanese Viper consists mainly of rodents. When these prey are not available, it may also feed on lizards, frogs, birds, fish or some insects.


The Japanese Pit Viper is ovoviviparous, which means that the eggs hatch inside the female’s body.

The breeding season takes place between August and September. Generally, the female mates at most once a year, or even every two years.

To protect themselves against their predators, pregnant females move together.

A litter includes on average between 2 and 15 babies. As soon as they are born, they strongly resemble the adults and are already autonomous.


According to the IUCN red list, the Mamushi is not considered to be in danger of extinction.

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