The Oki Salamander is a small species of salamander only found in Dōgo Island. Aside from being a unique species, it also has extremely unusual features.
Small species of salamander (Hynobius) are split into two types; the lotic type, which live in streams and rivers, and the lentic type which live in pools of stagnant water. The Oki Salamander inhabits mountain streams (lotic type) but has a mix of features of both types of salamander.
Genetic research has discovered that the species originally evolved from the lotic type to the lentic type. However, in order to adapt to an environment with mountain streams it once again developed lotic features. This kind of ‘reverse evolution’ is not well-known of even among plant and animal species all around the world. Considering this, the Oki Salamander is a very precious species for research about evolution.
In 2005 (updated in 2010), the Oki-Daisen National Park was added to a list of ‘last habitat of an endangered species’ by the Alliance for Zero Extinction (AZE), an international initiative composed of non-government biodiversity conservation organizations. The Oki Salamander is one of 920 species in 588 locations around the world on this list.