Japanese Giant Salamander
Appearance
The Japanese Giant Salamander has a long flat elongated body. Their skin is coloured grey or brown on the top and is slightly paler on the underside. The skin is wrinkled and these help to increase the surface area of the body giving more opportunities for gas transfer across the skin. On the head and neck the skin is covered with many wart like bumps.
Their legs are short and both the fore and hind limbs are the same length. The eyes are incredibly small and have no eye lid.
An average Japanese giant salamander measures up to 1.4m (4.6ft) long and weighs 23kg (55lbs). This makes them the second largest salamander in the world after the Chinese giant salamander (Andrias davidianus).
Diet
The Japanese giant salamander is a carnivore. They feed on fish, insects, crustaceans and small mammals.
On the head of the salamander they have a range of bumps which are sensory organs they can use to sense food. This is useful as they have poor eyesight. They have negative pressure in their mouth which is used to suck food in.
They may go several weeks between meals.
Scientific Name
Andrias japonicus
Conservation Status
Near Threatened
Weight
23kg (55lbs)
Length
1.4m (4.6ft)
Lifespan
Up to 55 years
Diet
Carnivorous
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Range
As the name suggest Asia is the native home of the Japanese giant salamander where they are found solely in Japan. They are found in the South of the country throughout Honshu, Kyusyu and Shikoku.
Habitat
Japanese giant salamanders live in fast flowing rivers which are cold and provide an abundance of oxygen. Typically the base of these rivers is covered with rocks or gravel. They will hide under large rocks during the day.
Reproduction
Breeding takes place in Autumn from August to October. The males will occupy a den within a cavern or burrow. They are aggressive in their efforts to gain a den and defend this and males may die in this process.
Males dig a spawning pit, a hole in to which females deposit their eggs and the male then fertilizes these. Multiple females may lay their eggs in the same pit and the same male can fertilize all of these.
Once the females deposit the eggs they leave and it is then the responsibility of the male to protect the eggs. He will stay with the eggs for the next 60 days and protect them from predation. Predators of eggs include fish and other adult salamanders.
A total of up to 500 eggs may be laid. The eggs resemble a string of beads. The eggs hatch between 40 and 60 days with the length of time determined by the temperature of the water they are incubating in.
As an amphibian the Japanese giant salamander hatches as a larva (similar to how frogs hatch as tadpoles). These have gills to breathe which they will lose at 3 years old at which point they begin to breathe through their skin. It may take up to 10 years for them to reach their full adult size.
Sexual maturity is achieved at 5 years old. Males may need to reach a larger size to be able to successfully mate as they need to be able to fight for a den.
Behaviour
As a nocturnal species the Japanese Giant Salamander will rest during the day and then emerge at night to feed.
They maintain a home range with those for males and females overlapping.
As an amphibian most of their breathing is done through the skin.
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Predators and Threats
The main threat to an adult Japanese Giant Salamander is humans. They are a traditional delicacy which is often eaten.
They also come under threat from the building of dams in their habitat and the introduction of invasive species such as the larger Chinese giant salamander.
Their skin colour helps them to blend in with their environment and avoid predation.
When under threat they can exude a milky like substance from their skin. The benefit of this is unknown but it may be toxic to predators.
Like many amphibians in the world the Japanese giant salamander has contracted chrytid fungus and this is spreading through the population.
Quick facts
Japanese giant salamanders are the second largest salamander in the world after the Chinese giant salamander.
Photo Credits
Top
RedGazelle123 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
Bottom
V31S70 / CC BY (https://creativecommons.org/licenses/by/2.0)
References
Burnie, D., 2011. Animal. 3rd ed. London: DK
Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley.
Smithsonian's National Zoo. 2020. Japanese Giant Salamander. [online] Available at: <https://nationalzoo.si.edu/animals/japanese-giant-salamander> [Accessed 1 June 2020].
Genomics.senescence.info. 2020. Japanese Giant Salamander (Andrias Japonicus) Longevity, Ageing, And Life History. [online] Available at: <http://genomics.senescence.info/species/entry.php?species=Andrias_japonicus>
[Accessed 1 June 2020].
Yoshio Kaneko, Masafumi Matsui. 2004. Andrias japonicus. The IUCN Red List of Threatened Species 2004:
e.T1273A3376261. https://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T1273A3376261.en. Downloaded on 01 June 2020.
Winkler, L. 2006. "Andrias japonicus" (On-line), Animal Diversity Web. Accessed June 01, 2020 at https://animaldiversity.org/accounts/Andrias_japonicus/
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