Ophisternon candidum is one of the most unique and interesting animals I have ever encountered. It lacks eyes but has very well defined lips (at least for a fish). (Mees, 1962)Photo courtesy of Dr.Gerry Allen While it may appear to have a very unique morphology, one of its closest relatives Ophisternon infernum, exhibits the same atrophy of its eyes. (Humphrey & Feinerg, 1995)

 It is unique in being one of only two troglobitic invertebrates that call Australia home. (Mees, 1962) It is also quite rare. There are only thirteen instances of these creatures appearing together in pairs and only three instances of them being found together in a set of triplets. (Humphreys, 1999) With that being said, it is quite possible that the blind cave eel is found more with its troglobitic vertebrate counterpart the blind cave gudgeon than it is with itself. There has been only one instance of the blind cave eel being found without its partner. (Humphreys, 1999) While this animal and other troglobites like it might seem like definitive evidence for convergence and evolution in general, this wasn't always the case.

Opihsternon infernale. A very close relative and an excellent example of convergence. Courtesy of Dr. Thomas M. Iliffe The history of hypogean fishes in general is a sadly under-researched history. Since their first discovery there has been a debate about how they came about. There have been several phases in the dominant thought on these fishes, however each phase follows a similar pattern: a reemergence of an old idea butting heads with the most modern ideas of evolution of the time. This has involved the reemergence of Lamarck's ideas on evolution and in time led to the term regressive evolution. Those who subscribe to the idea of regressive evolution have been put in to the orthogenesis school. This school of thought believes that evolution is directional and has some sort of progression towards an ideal form. Thus, a cave dwelling creature moving away from the peak of evolutionary progress (humans), is obviously regressing. Evolution has no directionality; this is one of the main tenets of evolution taught in almost every class that covers the subject. Selection pressures within the caves have simply pushed its denizens towards their current forms. (Romero, 2001)

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