The Japanese giant salamander, scientifically known as Andrias japonicus, is one of the largest amphibians in the world. With staggering lengths of up to five feet, the species is mainly found in Japan’s cool, clear streams and rivers. This amusing creature exhibits a range of unique traits that have piqued the interest of scientists and nature enthusiasts. Below are some of its behaviors discussed in detail.

The Physical Appearance of a Japanese Giant Salamander

The Japanese giant salamander has brown and black, blotchy-looking skin. The species also have many small warts throughout their body, with more on the head. It has tiny eyes without eyelids and a poor sense of sight.

Fascinatingly, their mouth extends across the head at full length and opens to the width of their whole body. On its neck, there are large folds of skin that conveniently increase the body’s surface area, necessary for epidermal respiration.

Where to See Japanese Giant Salamanders

Japanese giant salamanders are well-adapted and thrive in habitats with cold, fast-flowing mountain streams and rivers with an adequate oxygen supply. These environments support their nocturnal hunting and breeding habits.

As its name suggests, you will likely find Japanese giant salamanders in Japan, specifically on Honshu Island. Smaller populations can be found in northern Kyushu and Shikoku.

What Do Japanese Giant Salamanders Eat?

This species primarily feeds on what they can find. This can be fish, crustaceans, insects, and small mammals. They use a sit-and-wait hunting strategy, relying on their inconspicuous color to camouflage and ambush the prey. It has prolonged metabolism rates, so it can sometimes go for weeks without eating.

These salamanders have a highly sensitive lateral line system that detects vibrations and motions in the water. This allows them to accurately locate their prey, even in pitch-black darkness. As soon as the prey is within reach, they use the rapid suction mechanism to ingest it whole.

Can You Eat Japanese Giant Salamander?

Despite the Japanese authorities designating the species as the country’s special natural monument in 1952, Japanese giant salamanders are occasionally hunted for meat. Most Japanese consider them a delicacy. Interestingly, the species doesn’t have any natural predators.

Reproduction and Breeding Patterns of Japanese Giant Salamanders

Adult males are very territorial, much so during the breeding season. They build and guard territories in underwater caves or crevices, which work as their shelters. Territorial conflicts can cause aggressive interactions where the male may fight intruders to establish dominance and maintain control of the territory.

The salamanders’ breeding season falls in late summer to early autumn. It is characterized by males becoming more aggressive and territorial, competing for the best sites, and females. Males attract females by emitting pheromones and performing courtship activities.

Once a female expresses interest, the male guides her to his breeding site. The female lays her eggs in a safe, protected location in the male’s territory, and then the male fertilizes them externally. Unlike many amphibians, male Japanese giant salamanders display a form of parental care and affection.

After fertilization, the male salamander keeps the eggs safe from predators and ensures they stay well-oxygenated by fanning water over them. This care goes on for several weeks until the eggs hatch.

Adaptations and Defensive Behaviors of Japanese Giant Salamanders

The mottled and dark skin of the Japanese giant salamander helps it camouflage and blend seamlessly into the rocky riverbed and stream banks, hiding it from predators and prey. When threatened, Japanese giant salamanders excrete a sticky, milky substance with a distinct smell like Japanese pepper that keeps the predators away.

They can also regenerate lost limbs, which is an added advantage for surviving predator attacks or territorial conflicts with other salamanders. Being active at night (nocturnal) allows them to avoid many active during-the-day (diurnal) predators.

The salamanders hide in their crevices or under rocks during the day and get active at night. This is when they hunt and take part in social activities.

How Do Japanese Giant Salamanders Communicate?

Japanese giant salamanders communicate through various vocal expressions, which comprise grunts, squeaks, and hisses, depending on the message they want to pass. These sounds serve diverse purposes, such as attracting their mates, scaring rivals away, and expressing pain or fear.

Pheromones also play a major role in their communication, especially during the breeding season. These chemical signals help the males and females locate each other and enable mating.

Are Japanese Giant Salamanders Endangered?

Pollution, dam construction, and deforestation are significant threats to the salamander’s habitat. These activities lower water quality and disrupt the natural flow of rivers and streams, which they hugely rely on.

Changes in temperature and precipitation also affect the availability of appropriate habitats and food sources for the Japanese giant salamander. Warmer water temperatures reduce the oxygen concentration of the water, hindering their respiratory abilities. As it stands, the Japanese giant salamanders are categorized as endemic.

The Key Takeaway

The Japanese giant salamander is a special species with distinct characteristics that allow it to thrive in its designated habitat. It is a nocturnal amphibian that can be as big as five feet, lives in a fully aquatic habitat, and can regenerate lost limbs. Unfortunately, factors such as pollution, deforestation, and dam creation threaten their survival.

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