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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
Sinkhole: A surface depression in cave country. A s in khole is produced when the roof of a cave collapses or 
when limestone rock underlying the soil is slowly dissolved by water. 
Species (singular or plural): A group of plants or animals whose members breed naturally only with each other 
and resemble each other more closely than they resemble members of any similar group. A “new species” 
is one that has been recognized by an expert taxonomist, but is not yet described in the scientific litera¬ 
ture. 
Speleologist: A person who studies caves in any of their scientific aspects. See also Caver and Spelunker. 
Speleothem: A general term for any mineral deposit or formation found in caves, such as stalactites, stalag¬ 
mites, or gypsum flowers. 
Spelunker: A person who explores caves as a hobby or for recreation. In recent years this term has been 
applied more to the untrained cave visitor. “Cavers rescue spelunkers” is one way that cavers explain the 
difference. See also Caver and Speleologist. 
Stygobite (stygobiont): An aquatic troglobite. 
Stygophile: An aquatic troglophile. 
Stygoxene: An aquatic trogloxene. 
Terrestrial: Living on land. Not to be confused with “epigean.” Terrestrial cave animals include blind bee¬ 
tles, millipedes, spiders, and crickets. See also Aquatic. 
Troglobite (troglobiont): “Cave dweller.” An animal that is limited to caves and similar habitats, and exhibits 
troglomorphy. Also known as a “troglobiont,” obligate cavemicole, or obligate subterranean species. See 
Sket (2008). 
Troglomorphy: The physical characteristics of a troglobite or stygobite; e.g., reduced eyes and pigment, elon¬ 
gated appendages, well-developed tactile and olfactory organs, etc. 
Troglophile: “Cave lover.” An animal that can complete its life cycle in caves but may also do so in suitable 
habitats outside caves. Some troglophiles are cave-limited but may or may not e xh ibit some troglomor¬ 
phy, and may be relicts of climatic change. Facultative cavemicole is synonymous. Sket (2008) defined 
additional terms that are not used in this paper: eutroglophile is an essentially epigean species, but able 
to maintain a permanent subterranean population; subtroglophile is inclined perpetually or temporarily 
to inhabit a subterranean habitat but is bound to the surface for some biological functions (e.g., feeding). 
Trogloxene: “Cave visitor.” An animal that habitually enters caves but must return periodically to the surface 
for certain of its living requirements, usually food. Examples are bats, crickets, and many other species. 
Trophic levels: Feeding levels in a food chain, such as producers, herbivores, detritivores, predators, and so 
on. Most food chains include a maximum of four or five trophic levels. 
Twilight zone: The area of a cave where light penetrating through the entrance is sufficient to permit human 
vision. See also Zonation. 
Type locality: The place from which the name-bearing specimen (holotype) of a species is described. 
Variable-temperature zone: The area of a cave where air temperature fluctuates with the seasons. See also 
Zonation. 
Vertebrate: An animal with a backbone. The group includes fishes, amphibians, reptiles, birds, and mammals. 
Some amphibians and fishes live permanently in caves. See also Invertebrate. 
Water table: The upper level of the under-ground reservoir of water; the level below which the soil and all 
cracks and channels in the rocks are saturated. 
Zonation: The organization of a habitat into a more or less orderly series of distinctive plant and animal asso¬ 
ciations as a result of variations in environmental conditions. Zones in a cave are the twilight zone, the 
variable-temperature zone, and the constant-temperature zone, or simply the twilight and dark zones. 
