Cave Pod People
The most common cave dwellers are those which are mostly ignored: the
exoskeletoned creatures include insects, water dwelling crustacea, spiders,
and some just weird
critters. One of the most complete inventories of cave and spring dwelling
undertaken by James E. Gardner, then wildlife biologist for the Missouri
Conservation, from September 1978 to August 1984.
The result of his work, published as Invertebrate Fauna from Missouri
Springs by the Conservation Commission in 1986, is the most complete
invertebrate cave species in Missouri between two covers. In it, Gardner
describes 414 species
including:"a horsehair worm, two flatworms, three leeches, 30 snails, 19
isopods (11 aquatic and
eight terrestrial), 16 amphipods, nine crayfish, eight psuedoscorpions, five
ticks, 11 harvestmen,
36 spiders, 18 centipedes, a symphylan, 18 millipedes, 42 springtails, five
mayflies, a dragonfly, six crickets, 112 beetles, a psocid, eight
hemipterans, a homopteran, two
dobsonflies, 11 caddisflies, two stoneflies, nine moths, 25 flies, three
fleas, and 5 hymenopterans."
Out of these, Gardner found 39 troglobitic varieties of cave dwellers,
amphipods, decapods, gastropods...you get the picture. Nearly every
troglobite (except for a
flatworm) has the word "pod" somewhere in its scientific description.
Voila. The Pod People.
Rather than going into great detail on all 414 species (which took Gardner 72
pages, and whose
book is highly recommended for people interested in such things) here are
some of the highlights
of cave invertebrates:
Two troglobitic Missouri species, the Salem Cave Crayfish, Cambarus
hubrichti and the
Bristly Cave Crayfish, Cambarus setosus. Both are blind, white,
smaller and more slender
than aboveground (epigean) crayfish. Another noticeable feature are the
length of the antennae
when compared to epigean species. They are supposed to survive to great ages,
based on counts
of annular rings, though some people believe these rings actually are counts
of seasons of
abundant food, not years. The Salem Cave Crayfish occurs mostly on the
Salem Plateau, and the
Bristly Cave Crayfish occurs mostly on the Springfield Plateau. These
crayfish are commonly
found in caves and springs containing the cavefishes, though it is not
definitely known who is
predator and who is prey in this relationship. Some biologists have put
forward the theory, that in
a cave ecosystem, sheer luck, speed and size, not preference, determines who
Isopods are a fairly common crustacean in caves, in both troglobitic and
epigean forms. Some
isopods are terrestrial, and some are aquatic. They vary from microscopic to
one-half inch (1.4
cm) in size. They have segmented bodies, jointed legs, and vaguely resemble
They are scroungers, living usually in the water or in guano piles, and
feeding on microorganisms.
Isopods can be plentiful in caves with a large food supply.
Amphipods are also crustaceans, usually aquatic, which resemble tiny
shrimp--a curled body with
many joined legs beneath. The usually are found under the same conditions as
aquatic isopods, but
usually do not grow as large as them. Both troglobitic and epigean species
exist. Both isopods
and amphipods are part of the diet of cavefish, crayfish, and salamanders..
Cave Insects, Arachnids, and Their Relatives--
Among the most common insects and arthropods one runs into in Missouri caves
crickets, millipedes, centipedes, spiders and flies of various sorts. Some
are troglobitic, some are
merely epigean species which use the caves because they like the conditions.
insect species are noticeable smaller than their above ground counterparts.
large arthropod which looks like it escaped a Grade B movie set, are well
known from Missouri
caves. A large, fairly beautiful moth, Scoliopteryx libatrix
overwinters in a few caves.
Heliomyzid flies are very common in caves, and at one time or another, seem
to be lunch for just
about everyone. Of course, there is the webworm--the fungus gnat larvae who
wrote this home
page. And collembola, a primitive, fungus eating insect, which are everywhere
rotting stuff is to