Since cave-adapted arthropods exhibit reduced eyes and elongated sensory antennae [ 1, 2, 8], the loss of eyes as a result of selection for increased tactile sensitivity is an attractive general hypothesis for the convergent evolution of eye regression in cave fauna.
Because every hunting routine (for both free swimming and tethered larvae) commences with eye convergence, and the spontaneous rate of convergent saccades is very low, we could use eye tracking alone to determine that the animal has initiated hunting behavior in response to a visual target.
If, as genetic data suggest, multiple entries to the subsoil have occurred in Palmorchestia, convergent morphological adaptation by eye degeneration and body depigmentation could have arisen independently by different mutations, as has been shown to occur in Astyanax fasciatus [ 27].
Specifically, we considered two eye convergence-triggered time windows: the "pre-conv" window compared activity during 1.65 s immediately prior to the convergent saccade to activity at corresponding times in non-response trials.
What makes them different is that they have lost their eyes through convergent evolution...many times, in many places.
The discussion about the forces driving convergent evolution of reduced eyes and loss of pigmentation in typical cave-living animals was initiated very early in the history of evolutionary theory [ 4].
The left eye showed a convergent position.
She had a hemangioma planum on the right side of her face, low set ears, and convergent strabismus on the right eye (Table 1).
At the age of 1 year, she had been referred to an ophthalmologist for a convergent position of the left eye.
The physical examination revealed pallid and dry skin, lack of subcutaneous fat, thin and triangular face, sunken anterior fontanelle, muscle wasting, restlessness, motor hyperactivity, euphoria, nystagmus and convergent strabismus of the left eye.
