Blind cave eel

In 1962, the species had an original description of Anommatophasma candidum with the word "Anommatophasma" representing a new genus. The etymology of the scientific name Ophisternon candidum comes from the Greek word which means "serpent", the Greek word which means "chest" and the Latin word which means "white" referencing its skin colour. The vernacular name of Ophisternon candidum is blind cave eel in Australia and United Kingdom, whereas its name is blind freshwater eel in the United States. The vernacular name suggests its eel-like body, living in a cave and having no visible eyes. == Description ==

The blind cave eel is Australia's longest cavefish and may grow up to . However, common total lengths for mature adults have an average of and range between . == Distribution and genetic difference ==

The Blind cave eel has only been spotted 36 times in 20 sites from 1959 to 2017. Observations were made in 3 regions; Cape Range, Pilbara, and Barrow Island, which makes the blind cave eel endemic to north-western Australia. In the Cape Range region, there are 14 sites in total as recorded by the Western Australian Museum, making the region the most common place to spot a blind cave eel. Sites include Tantabiddi Well, Milyering Well, Ned's Well, Dozer Cave, Pilgramunna Well, Kubura Well cave, South of Yardie Creek, Mowbowra Well, Kudumurra Well, Wobiri Rock Hole, New Mowbowra Well, Tidal Cave, Kudamurra Well and an unnamed site with a coordinate of 21'47'S, 114'10'E. In the Pilbara Region, there are 3 sites including the Exploration bore BC186-155, Borehole JW023, and Borehole JW024. In the Barrow Island Region, there are 3 sites including the Seismic testing site E1918, Anode Well T2, and Anode Well L15. Both the Pilbara Region and the Barrow Island Region were not discovered until 2009, from 1959 to 2009 blind cave eels were assumed to be restricted within 100 km in the Cape Range subterranean. Recovery of a specimen from the mineral exploration bore BC186-155 in the Pilbara region near Bungaroo Creek in 2009, extending the known distribution range to 200 km. Notably, the blind cave eel near Bungaroo shows a genetic difference from those from other locations, possibly due to sufficient isolation resulting in an evolving independent parentage. == Habitat ==

The preferred habitat consists of underground waters and caves, in which the waters have a very high salinity level and are stratified markedly from the surface freshwater. The underground waters have a pH value of 7–8, salinity level of 1–8%, hardness (CaCO3) of 220–1500 mg and conductivity of 115–1250 mS. Although it is altered by marine tides, there is a deficiency of surface connection with the surface freshwater. The blind cave eel is restricted to underground waters, in which only two vertebrate animals in Australia share such habitat, the other being the Blind gudgeon (Milyeringa veritas). The underground waters where the blind cave eel lives are a lightless subterranean system, indicating the adaptiveness of a total darkness environment. The blind cave eel likes to live in pastoral wells, dark caverns, fissures, under coastal limestone or burrow into sediments with a soft bottom. Due to the blind cave eel's habit, it is very difficult for people to access underground waters and its sites are usually too small. Therefore, most of the recorded sightings are by observation rather than voucher specimens because it is unlikely to trap or net the blind cave eel. Moreover, the recorded sightings lack the lower part of the anchialine system and there are no more than three blind cave eels spotted on a single occasion. == Feeding ==

The blind cave eel feeds primarily based on crustaceans in subterranean and other cave substrate organisms, but have also been documented to feed on terrestrials washed into the cave system. In the gut contents examined by the Western Australia Museum, Halosbaena tulki, Stygiocaris, Philosciidae, and larvae are found. Despite being restricted to subterranean waters adapting a characteristic of faecal ooze, it is sometimes observed in shallow water lying on rock surfaces on its own or in pairs. == Reproduction ==

Little is known about the blind cave eel's life cycle due to the inaccessibility of voucher specimens. For mating behaviour, the male blind cave eel tends to take the responsibility of building a nest or burrow and guarding over it. == Importance to humans ==

The blind cave eel has no threat to humans. It is not consumable, and fisheries have no interest in it. == Conservation ==

Conservation status The Environment Protection and Biodiversity Conservation Act 1999 assessed the blind cave eel as vulnerable, and the Endangered Species Protection Act 1992 also assessed it as vulnerable. In the Wildlife Conservation Act 1950 in Western Australia and Wildlife Conservation Notice 2006(2) specially for protected fauna, the blind cave eel is accessed as rare. ==References==