Conference Paper
Eye development in the cave fish Garra barreimiae
Aden, E.
Record Number:
4735
Year:
2010
Editor:
Moskric, A. and Trontelj, P.
Abstract:
Eye degeneration is a general
evolutionary tendency shown in many animal groups that are adapted to
dark environments. Inside the Hoti Cave located in the Jabal Akhdar
mountains in Oman lies a subterranean lake, which is home to the blind
fish Garra barreimiae. Outside the cave, Garra barreimiae is a common
species of eyed epigean surface fish. The eyes of the blind cave fish and
of its epigean ancestor have been studied comparatively. The eye
structure of the surface fish is a typical teleost eye. Parts of the eye of the
cave fish show hypertrophy. Individuals compensate the lack of a lens in
various ways with extreme growth of different parts of the eye. For
instance, the anterior eye chamber is often filled out with a derivative of
the annular ligament, and as a result the pupil no longer transmits light.
The eye rudiment of the Garra barreimiae is not sunken in the orbit as is
the case with other cave fish species. From these examples we can
conclude that the adult cave fish population is very heterogeneous with
regard to the size and structure of the eye rudiment. To understand how
this diversity evolves, the ontogenetic eye development was investigated.
During early ontogeny the differentiation of the eye of hypogean Garra
barreimiae is similar to the epigean one. All major structures are present.
However, the lens remains in the embryonic stage, and no lens
differentiation occurs. It disappears altogether at the age of three months.
Initially there is a complete laminated retina with typical opsin expression
in the photoreceptor cells. But opsin expression remains at a low level
and ceases at the age of four months. On the other hand, other retinal
strata like the amacrine cell layer are well differentiated in juvenile cave
Garra and remain functional for longer than the photoreceptor cells. In
adult animals, on the other hand, no evidence of functional retina cells
could be detected.
Times Cited:
1
Conference Name:
20th International Conference on Subterranean Biology
Conference Year:
29 August-3 September 2010
Conference Location:
29 August-3 September 2010
Conference Location:
29 August-3 September 2010
Relevent Species: