Habu Snake

The habu snake, also called the Kume Shima or Okinawa Habu, is a venomous snake from Japan. Its bite can cause serious injury, though it is not usually fatal. Habu snake numbers are decreasing, perhaps due to habitat loss and overhunting. It is one species of Japanese snake used in the making of snake wine.

4 Amazing Facts About Habu Snakes!

• It’s very rare but habu snakes have been known to revive (and bite!) after fermenting in the wine for months!
• These snakes can only be found on a small group of islands in Japan.
• These snakes are pit vipers, similar to the much-feared fer-de-lance of South America.
• While most pit vipers give birth to live young, the habu lays eggs.

Scientific Name

The habu snake has several common names, including Okinawa Habu and Kume Shima. It also has several scientific names. Most often, it is listed as Protobothrops flavoviridis. Other sources list it as Trimeresurus flavoviridis. Both classifications indicate its relationship to other pit vipers. The Latin flavoviridis means “yellowish green” and describes the snake’s color. It is of the class Reptilia (reptiles) and the family Viperidae (viper snakes).

Historically, scientists have struggled to classify the habu snake effectively. Other scientific name synonyms include Bothrops flavoviridis, Trimeresurus riukiuanus, and Lachesis flavoviridis.

In the past, two subspecies were recognized: P. flavoviridis tinkhami and P. flavoviridis flavoviridis.

Evolutions and Origins

The habu snake is a type of pit viper belonging to the Viperidae family. The oldest fossil evidence of vipers dates back to the early Miocene 23.03 million years to 15.97 million years ago, although some scientists believe vipers are even older and their lineage can be traced to the early Eocene 56 million years to 47.8 million years ago.

Vipers evolved to include the loreal pits characteristic of all pit viper species as well as adapting to their environments in ways including generalist and specialized diets, nocturnal and diurnal lifestyles, and differing reproductive methods — with the habu snake being oviparous unlike most pit vipers, which give birth to live young.

Appearance

The habu snake is a large pit viper; in fact, it is the largest snake in its genus. Its average length is 4 to 5 feet, but individuals 7.9 feet in length have been observed.

This snake has a large head and a slender body. Its scales are small. Its background color is brown or olive green, with dark green or darker brown blotches on top. The edges of the blotches are yellow, and yellow spots may also occur. Often, the blotches fuse to form a wavy line down the back. The snake’s belly is white with dark edges.

How to identify habu snakes:

• 4 to 5 feet in length
• Blotchy olive green or brown pattern
• White belly edged in darker colors.

Behavior

These snakes are aggressive when disturbed, resulting in a relatively high number of snake bites. Decades ago, hundreds of people were bitten by habu snakes each year. Today the numbers are lower at about 2 bites per 1,000 people. However, this rate is still considered very high.

People may encounter habu snakes when visiting cemeteries or historic structures, as the snakes like to rest along rock walls. People may also be bitten if they step on the snake, as it is a terrestrial or ground-dwelling species. Bites are more likely to occur at night since the snake is nocturnal. It may enter homes in search of food sources, namely mice or rats.

Venom: How Dangerous Are Habu Snakes?

The venom of the habu snake is highly toxic. It contains hemorrhagic components and cytotoxins. The bite causes symptoms such as nausea, vomiting, and hypotension (low blood pressure).

People do not usually die from habu snake bites. However, if you are bitten, you should seek medical care immediately. Even after receiving treatment, 6 to 8 percent of bite victims suffer permanent disability, losing motor function in the hands or legs due to the venom’s effects.

Habitat

These snakes have a very limited range, living on the islands of Okinawa, Amami, Amakarima Island, Kerama-Retto Island, and Okinawajima Island, of the Ryuku Archipelago in Japan.

If you want to see one of these snakes in the wild, look for it on the larger volcanic islands in this region, where it is relatively common. It is generally not found on the smaller coral islands.

Its favorite habitat is in the transitional zone between cultivated fields and palm forests. You may also see one of these snakes if you visit old tombs, caves, or structures with rock walls.

Sadly, the most common place that people may spot these snakes is in marketplaces highly trafficked by tourists. However, these snakes are no longer living and have been used to create habu sake, or snake wine, a supposedly medicinal drink with a whole snake coiled in the bottle. Though snake wine has been made and used for centuries, its sales have recently increased. Why? Because tourists want to take home the fearsome-looking snake in a bottle.

Diet

Habu snakes hunt small mammals, including rats and mice, as well as birds, frogs, and other reptiles.

As pit vipers, habu snakes have heat-detecting pits on their faces. They use these to sense the body heat of birds and mammals. This is especially helpful for this nocturnal snake. It hunts at night, so it can not rely on its vision in the low light. When the habu snake finds prey, it strikes quickly. This snake has a long reach compared to other snakes. Once bitten, the venom kills the small animals. After they cease to struggle, the snake can swallow them safely.

Predators and Threats

People collect the snake for use in habushu or snake wine, leading to overhunting and a decline in population at least since the 1970s.

Additionally, the small Asian mongoose, a well-known snake predator, was introduced to Okinawa in 1910 specifically for the purpose of reducing habu snake populations.

Reproduction, Babies, and Lifespan

Unusually for a pit viper, the habu snake lays eggs instead of giving birth to live young. The breeding season occurs early in the spring months and the female lays up to 18 eggs in the middle of summer. After around 5-6 weeks of incubation, the snakelets emerge and measure around 10 inches long. They are independent and fully venomous from birth.

The lifespan of habu snakes in the wild is on average 7-10 years, with some known to have reached 15 years of age.

Population and Conservation

The total population of these snakes is unknown, but researchers believe that the population is in decline. One reason is an observable decrease in the number of bites each year. On Okinawajima Island, around 300 people were bitten by these snakes each year in 1970. By the 1990s, 100 were bitten each year. In 2015, fewer than 30 bites occurred.

The pattern is similar on Amamaioshima Island, where 300 bites per year in 1950 dropped to less than 100 bites per year by 2000.

The habu is currently rated as an animal of Least Concern by the IUCN Red List of Threatened Species. This rating was assigned in 2016.

1. BBC, Available here: https://www.bbc.com/travel/article/20151113-the-wine-that-comes-with-added-bite
2. Atlas Obscura, Available here: https://www.atlasobscura.com/foods/snake-wine-china-vietnam
3. IUCN Redlist, Available here: https://www.iucnredlist.org/species/96265495/96265515