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Blind Eyes: Troglobites include a variety of unusual creatures: eyeless fish, white crayfish, Blind eyes salamanders, Blind eyes beetles, and white, eyeless flatworms, amphipods, and isopods. Surface-dwelling species of animals most closely related to troglobites show a tendency toward the same physical characteristics: reduced eyes and pigment, thinner skin or exoskeleton, elongated or otherwise modified tactile organs, and reduced but efficient activity and metabolism. They are considered to be "preadapted" to cave conditions as the ancestors of present-day cave dwellers must have been.
The eyes of a spider are usually near the front or anterior end of the head, but some are directly on top. They are single facets, hence are called simple eyes. They may number two, four, six, or eight; eight is the usual number. However, the cave spiders lack eyes entirely. Regardless of the number, the eyes are always placed in a definite arrangement. Often some pairs are much larger than others.
Caves harbour a variety of animal life specially adapted to the dark environment, including Blind eyes, colourless, almost transparent shrimps, worms, mites, insects and sightless newts, often called Blind eyes fish. These creatures live permanently in caves. Bats, also common in cave systems, have weak eyes and depend mainly on their sonar systems to guide them through dark tunnels. Every night hundreds of thousands of bats emerge from the Carlsbad Caverns in New Mexico. Within 15 minutes' flight of the caverns is the Pecos valley, where the bats feed on insects, returning to the caves shortly before dawn.
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