298 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
Hyporheos: From Greek, hypo (below) and rheos (flow). The hyporheic zone is beneath and alongside 
a stream bed, where there is mixing of shallow groundwater and surface water. The biological commu¬ 
nity that inhabits this zone is called the hyporheos. 
Insectivore: A member of the Order Insectivora, e.g., shrews and moles, or an animal that feeds on insects. 
Almost all species of North American bats (Order Chiroptera are insectivorous. See also Carnivore; Her¬ 
bivore; Omnivore. 
Invertebrate: An animal, such as a planarian, snail, or crayfish, without a backbone. See also Vertebrate (Phy¬ 
lum Chordata). 
Joint: A more-or-less vertical crack in bedrock, along which caves often form through dissolution by ground- 
water. 
ka: Thousands of years ago. 
Karst: Landscapes formed by the dissolution of soluble rocks such as limestone, dolomite, and gypsum, with 
underground drainage systems, caves, s inkh oles, dolines, and springs. Also the typical surface terrain of 
a limestone region. See also Epikarst and Pseudokarst. 
Larva (plural larvae): An active immature stage in an animal’s life history when its form usually differs from 
the adult form, such as the grub stage in the development of a beetle or the tadpole stage in the life his¬ 
tory of a frog. See also Metamorphosis; Pupa. 
Lava tube: A natural conduit formed by flowing lava which moves beneath the hardened surface of a lava 
flow. Tubes can be actively draining lava from a volcano during an eruption, or can be extinct, meaning 
the lava flow has ceased and the rock has cooled and left a long, cave-like channel. 
Limestone, marble: Sedimentary rock composed primarily of calcite (calcium carbonate). It usually origi¬ 
nates through the accumulation of calcareous (limy) remains of marine animals. Because limestone is 
easily dissolved by carbon dioxide in water, caves are more common in limestone than in any other type 
of rock. Marble is a metamorphic rock that may be foliated or non-foliated, composed of recrystallized 
calcite or dolomite. 
Littoral: On the shore or coast. A sea cave is a littoral cave. 
Ma: Millions of years ago. 
Mammals: The class of animals that includes bats, mice, man, and many others. They typically have a body 
covering of hair and give birth to living young, which are nursed on milk from the mother’s breast. 
Marine relict: An animal whose presently extinct ancestors lived in salt water but became adapted to life in 
fresh water when an area formerly covered by the sea became dry land. 
Mesozoic Era: An interval of geological time from about 252 to 66 Ma (million years ago). 
Metamorphosis: A change in the form of a living thing as it matures, especially the drastic transformation 
from a larva to an adult. See also Pupa. 
Metamorphism: The change of minerals or geologic texture in pre-existing rock, without the rock melting, 
e.g., limestone metamorphosed into marble. The change occurs primarily due to heat, pressure, and the 
introduction of chemically active fluids. The chemical components and crystal structures of the minerals 
making up the rock may change even though the rock remains a solid. 
Microclimate: “Little climate.” The environmental conditions, such as temperature; humidity, and air move¬ 
ment, in a very restricted area, such as a sheltered nook in a cave wall or beneath a rock. 
Microhabitat: A miniature habitat within a larger one; a restricted area where environmental conditions dif¬ 
fer from those in the surrounding area. A sheltered nook in a cave wall is an example of a microhabitat 
within the cave. 
Mine: A man-made vertical shaft, sloping or horizontal excavation (slope or adit) in the earth from which min¬ 
eral substances are taken. In this study we use “mine” to refer generally to abandoned or inactive under¬ 
ground mines which may be in any type of hard rock, and in which cave-inhabiting species may occur. 
Many different m in erals are mined in California. The term may also refer to an open quarry. 
Mold: A microscopic form of fungus responsible for much food spoilage and, in caves, for conspicuous tufts 
quickly covering scats, dead insects and bats, and even wooden structures such as ladders. 
Neotenic: Retaining juvenile traits as an adult, as in salamanders that retain their gills throughout life. 
Omnivore: An animal that habitually eats both plants and animals. See also Carnivore; Herbivore; Insecti¬ 
vore. 
