Hynobiidae, commonly known as Asiatic Giant Salamanders, are primitive salamanders found all over Asia, from the Urals to Japan and are mainly above 40°N latitude. There are nine genera with 54 species as follows: Batrachuperus (5 species), Hynobius (32 species), Liua (2 species), Onychodactylus (2 species), Pachyhynobius (1 species), Paradactylodon (3 species), Pseudohynobius (6 species), Ranodon (1 species), and Salamandrella (2 species). The current conservation status of Hynobiidae is as follows: 32.9% is Endangered, 21.5% is Vulnerable, 15.2% is Critically Endangered, 15.2% is Least Concern, 10,1% is Near threatened, and 5.1% is Data Deficient. As for the systems Hynobiidae Inhabit are 34.2% Freshwater and Marine, 32.9% Terrestrial and Freshwater, and 32.9% Terrestrial.
Hynobiids are heavy-bodied, thick-tailed salamanders with four short, well-developed limbs. Their size is less than 100 mm TL except in Ranodon sibiricus where their size is 250 mm TL. Their lower jaw has separate angular and prearticular bones, the upper jaw has both premaxilla and maxilla, and the lacrimal is present. The lacrimal bone provides support to the structure of the lacrimal apparatus, which secretes tears to lubricate the eyes. Adult Hynobiids lack gills, gill slits, and nasolabial grooves, but they do have moveable eyelids. In contrast, larval Hynobiids have external gills, four pairs of gills slits, and a caudal fin, all of which are lost at metamorphosis. Coastal grooves are present on the trunk and they have well-developed lungs, however, lungs are absent in Onychodactylus. Females lack spermatheca in the cloaca as both females and males only have ventral cloacal glands. Lifespan varies amongst males and females and can vary between 8-20 years.
Most Hynobiids are terrestrial except during the breeding season when they migrate to the water. Hynobiids display little evidence of courtship and may use chemical communication to bring both males and females together. The appearance of eggs extruding from females’ vents also appears to be a visual signal that stimulates male Hynobiids. Fertilization is external as females deposit eggs in a pair of gelatinous masses (35-70 eggs), one from each oviduct, and males shed their sperm directly on the egg masses. One exception to this pattern is the Ranodon species. In this species, males produce a rudimentary spermatophore, and the female deposits eggs in the spermatophore instead of taking its sperm packet into her cloaca. Parental care is present in the form of egg-guarding.
Both the larval and adult Hynobiid diet consists of insects and invertebrates.