"Dripstone Wall" by NPS Photo , public domain
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Mammoth Cave
National Park Service
U.S. Department of the Interior
Mammoth Cave
National Park
Biology and Cave Life
A Diversity of Life
Mammoth Cave National Park’s 52,700 acres constitute one of the greatest protectors of biological diversity in Kentucky. The surface contains animals typical of an eastern hardwood forest. Larger animals include white-tailed deer, fox, raccoon, opossum,
woodchuck, beaver, rabbit and squirrel. Smaller animals, such as bats, mice and chipmunks, also abound. Many reptiles and amphibians find protection in the park too.
Birds such as mourning doves, whippoorwills, owls, hawks, woodpeckers, and warblers fly through Mammoth Cave’s forests. Wild turkeys reintroduced in 1983 are now
regularly seen by visitors.
Varied Forests
While most of the park consists of second-growth
woodland, a number of unique communities of
plants – hemlocks and other northern plants growing in cool moist ravines, wetlands, and open barrens with prairie vegetation – contribute much to
the variety in plant life and harbor many of the
park’s rare species. Currently, botanists are updat-
ing the park plant list. So far, 872 species of flowering plants have been confirmed, and the list is still
growing. Of these species, 21 are currently listed as
endangered, threatened or of special concern.
Active management, including prescribed burning,
may be needed in order to protect some habitats in
the park.
Teeming Rivers
The Green River, which meanders through the
park, supports an unusual diversity of fish, including five species that have not been found anywhere
else in the world, and three species of cavefish.
Another group of aquatic animals, freshwater
mussels, survive in the sand and gravel of the
Green River. Over 50 species of mussels, including
three on the endangered species list, live in the
park. Aquatic animals in the river play an important
role in providing nourishment for other animals –
in the cave, in the river, and on the land.
Things That Go Bump In
the Dark
On first glance, in walking into Mammoth Cave, the
dark and quiet passageways may appear nearly
devoid of life. But first impressions can be deceiving, and surprisingly, biologists have discovered
over 200 species of animals in Mammoth Cave!
Animals in the cave include everything from surface
animals that have accidentally stumbled or tumbled
into the cave – like raccoons and bullfrogs – to 42
species of troglobites, animals adapted exclusively
to life in the darkness. One of Mammoth Cave’s
claims to fame, besides its length and wealth of
human history, is its biological variety. The diversity
of cave animals in the Mammoth Cave area rivals
the richness of any caveland region in the world. To
a biologist, a cave is a wildlife sanctuary – a retreat
for animals so specialized in structure and habit
that they cannot endure conditions on the surface.
To understand the survival techniques of cave
animals, we need to first take a closer look at three
environmental factors governing Mammoth Cave.
life. The temperature of the cave varies due to air
movement near the entrances, the location (on
ridges or in valleys), and the temperature of water
entering the cave. In a sense, the cave has its own
weather system. Wind is created by temperature
differences between the entrance and interior
passageways. This causes a "chimney effect,"
resulting in a wind chill factor underground. The
chimney effect can also produce "rain" inside the
cave by altering the dewpoint. The final contributor
to cave weather is the barometric pressure. Barometric changes affect air movement, humidity levels
and dew points. Subtle weather changes in the cave
make it possible for a perceptive caver to discern
outside weather conditions, even though he or she
may be hundreds of feet below the surface.
First of all, the cave world does not change as
rapidly as our sunlit world; however, change does
occur. The cave has its own cycles and rhythms of
Secondly, Mammoth Cave is intricately tied to the
outside world. The cave is different from our
world, but the survival of cave life depends on the
surface. Plants, through photosynthesis and
through their own decay, release carbon dioxide
that combines with water in the air and in the soil,
to form weak carbonic acid that carves the cave. In
Thirdly, the lack of light produces stress in caves by
limiting the availability of food. Therefore, cave
animals must make behavioral, physiological, and
morphological adaptations to survive. Some animals, called trogloxenes (or cave visitors), regularly
visit or hibernate in caves but customarily leave
caves. By collecting food on the surface and then
returning to caves, trogloxenes play an important
role in providing food for cave animals that never
venture outside. Bats, cave crickets, and pack rats
are well-known trogloxenes.
No Vampires Need Apply
Although Mammoth Cave is not currently used by
large numbers of bats, twelve species, including two
endangered species, live here. As insect-eaters and
plant pollinators, bats may be among the most
beneficial animals to people and other living things.
By consuming huge numbers of insects, bats work
as a "natural insecticide," controlling crop pests
and insects that may spread disease. Little brown
bats, one of the common species in Mammoth
Cave, can eat 600 mosquitoes in an hour. In addi-
tion, many cultivated plants that we enjoy – including avocadoes, dates, peaches, bananas, and cashews – depend on bats for pollination. Despite their
value, many species of bats are needlessly threatened – by direct killing, by vandalism, by disturbance to hibernating and maternity colonies, by the
use of pesticides, and by habitat destruction. Consequently, bat populations in the United States and
throughout the world have been declining dramatically.
Hopping, Scuttling,
Swimming
When you visit Mammoth Cave, you’re far more
likely to see crickets than bats. Crickets, actually a
kind of grasshopper, are trogloxenes too. They
spend much of their lives in the cave but depend on
night-time forays on the surface to gather food.
Because Mammoth Cave lacks large bat populations, crickets are extremely important in delivering
energy, in the form of droppings, eggs, and carcasses, to other animals in the cave.
environment. Troglophiles include crayfish,
springfish, salamanders, and spiders.
addition, plants provide food and energy for underground animals. No matter how organic material
enters the cave, the web of the cave begins with the
sun.
Another group of cave animals, the troglophiles (or
cave lovers), have evolved a step closer to cave
dependency than the trogloxenes. Troglophiles
can survive for their entire lifetime in caves, but
they can also live exclusively on the surface, where
they select cool dark places reminiscent of the cave
In Danger …
The lifestyles of all cave animals highlight the
fragility and interconnectedness of the surface and
the cave environments. Ultimately, the energy that
feeds cave animals comes from the surface. In
addition, land-use practices outside the park impact water quality and the lifeforms in the cave.
EXPERIENCE YOUR AMERICA
Troglobites, the group of cave animals most highly
adapted to cave life, cannot survive outside caves.
Many, including eyeless fish and crayfish, illustrate
creative adaptations to their environment. With no
need for camouflage or protection from the sun,
many of these animals have lost pigmentation and
are white. Some have no eyes. Most have developed other highly sensitive sensory organs to
detect predators and prey. Because food in caves is
scarce, full-time cave dwellers tend to be smaller,
with lower metabolism and longer lifespans than
their surface counterparts.
Even visitors entering the cave impact the underground world. Lighting, trail construction, building
unnatural entrances, and noise from cave tours,
affect the inhabitants of this sensitive and fascinating underground world.