Visitors to the cave often wonder how the numbers can be estimated. 7,000,000 is a lot of bats. This has been reduced to a relatively simple calculation. Cavern authorities counted the number sleeping in one square foot of space, found between 250 and 300 could squeeze into the area. The number of square feet of ceiling space occupied by the sleeping creatures was then multiplied by the bats per square foot, and the estimate was reached.
Life in the cave, it seems, has been governed by the bat, and even this little fellow can hardly be said to live there. Actually, he only sleeps there winters and during the day. He can't live in the cave all the time since there is no food there for him.
Are there any living creatures that dwell in the cave all the time? Only those that can find food in the cave, and since the eternal darkness prohibits photosynthesis which is vital to all growing plants, other animals or insects would find a food supply almost practically nonexistent, at least any form of plant food.
Yet there are cave crickets. One species was found which was entirely new to science, and they named it after the Caverns, calling the species Ceutophilus carlsbadensis. Their eyes do not seem to function, apparently depending upon their long antennæ to guide them.
But what do they eat? The contents of their stomachs have revealed bits of insect remains which they have scavenged from the piles of guano. Thus the cave crickets depend upon the bat for their existence.
The cave worm, actually an insect's larva, and a small spider also make their homes in the cave. How long these insects have lived in the cave is anybody's guess. Naturalists think the first few crickets may have fallen into the cave and remained there due to the abundance of the food supply, living peacefully and multiplying at leisure.
But this cricket's Shang-ri-la lost its comparative safety one day, maybe centuries ago, when a cave mouse is thought to have fallen in. He found the crickets abundant and tasty and, since he couldn't climb out, stayed in his new subterranean home. Maybe later Mrs. Cave Mouse met the same fate and together they became parents and grandparents of litters who have lived in the cave ever since.
The cliff mouse also lives his complete life cycle in the black depths of the Caverns, and together with the cave mouse they have a carefree existence, for none of their natural enemies live in the cave.
Any herbivorous animals which might have fallen into the cave would soon die, for the only vegetation to be found in the cave, aside from a certain amount of mold, exists in scant proportions near the cave entrances where there is some light and a little moisture. Thus only carnivorous or insectivorous animals or insects could exist in the vegetation-free depths.
Of the animals which occasionally frequent the cave, the cacomixle, commonly known as a ring-tailed cave cat or even just "ring-tail," is perhaps the best known. This slender raccoon-like animal doesn't spend all his time in the cave, for he is able to crawl in and out, but he does raise his family in the cracks and crevices of the walls, and eats an occasional cave mouse or guano bat. Outside he eats fruit and other small animals and insects. Apparently they have never been too numerous in the Caverns.