The Hades’ snake moray (Uropterygius hades) is a slender, dark brown eel which stands out for its unique adaptations to and preference for dim, turbid environments.

Unlike most of its marine relatives, which thrive in coral reefs, it is at home in estuarine habitats, a characteristic that is unusual among the 230 known species of moray eels. It is distributed across the Central Indo-Pacific, and has been found in southern Japan, Taiwan, the Philippines, southern Java, and Fiji.

Accidental discovery

Its discovery was an accident. It happened when three researchers from National Sun Yat-sen University in Taiwan travelled to the Puerto Princesa Subterranean River in the Philippines to survey the aquatic fauna there and look for the bean-eyed snake moray, a cave eel. 

While they failed to find any bean-eyed snake moray eels, they ended up with a different "prize"-the discovery of a new moray eel species of moral eel and the bragging rights that came with that honor. 

One of the scientists, Dr. Wen-Chien Huang, drew inspiration from Ralph Fiennes' portrayal of Hades in the movie Clash of the Titans and named it "Hades’ snake moray". The name pays tribute to Hades, the Greek god of the underworld, reflecting its shadowy appearance, sensitivity to light, and preference for muddy river mouths. 

Avoidance of light

When kept inside a tank, the Hades’ snake moray demonstrated tail-first burrowing, a behavior which was unusual in morays. It also exhibited high sensitivity to light, and would hide if it was exposed to it.  Its small eyes and reduced head sensory pores suggested that it burrowed through muddy habitats, relying mainly on chemoreception than vision.