Cave Pod People
The most common cave dwellers are those which are mostly ignored: the invertebrates. These
exoskeletoned creatures include insects, water dwelling crustacea, spiders, and some just weird
critters. One of the most complete inventories of cave and spring dwelling invertebrates was
undertaken by James E. Gardner, then wildlife biologist for the Missouri Department of
Conservation, from September 1978 to August 1984.
The result of his work, published as Invertebrate Fauna from Missouri Caves and
Springs by the Conservation Commission in 1986, is the most complete listing of
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 diplurans, three
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, including isopods,
amphipods, decapods, gastropods...you get the picture. Nearly every invertebrate troglobite (except for insects and flatworms) 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:
|Salem cave crayfish
||Bristly cave crayfish
Three troglobitic Missouri species, occur here, the Salem Cave Crayfish, (Cambarus hubrichti) the
Bristly Cave Crayfish, (Cambarus setosus) and the Caney Mountain Cave Crayfish (Orconectes stygocaneyi). Cave crayfish are
than above ground (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 cavefishes. The Caney Mountain Crayfish, discovered in 1999, is the first of its genus to be found west of the Mississippi River. 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 gets eaten.
(Photo by David Ashley)
Isopods are fairly common crustaceans 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 household silverfish.
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.
(Photo courtesy Missouri Dept. of Natural Resources)
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 Snails and Cavesnails
(Fontigens aldrichi--photo by David Ashley)
Cave snails and (cavesnails) are of special interest to cave biologists, because these tiny creatures have a very limited range. The species shown above (golden circle is a man's wedding ring) are often found on the underside of stream cobble. Because they live in the water, they are very sensitive to changes in water quality. Of special interest is the Tumbling Creek cavesnail, one of the newest additions to federal endangered species list. This species, known only from one cave in southwest Missouri, took a tumble in numbers itself, probably due to mismanagement of land in the cave's recharge, which is now under reclamation.
One of a few Missouri troglobitic Planaria
That squishy bit of white Jello oozing about on a rock is most likely a planarian. Three species of blind planaria Sphalloplana evaginata, Sphalloplana hubrichti and Macrocotyla glandulosa are identified from here, but there most likely are other species. None can be said to have a common (or even pronouceable) name, but they do have that amazing ability of flatworms: if accidentaly broken in reasonably sized pieces, they can regenerate. They also are found outside, in at least one of the cave effluent streams, though you have to turn over a lot of rocks to find them!
Cave Insects, Arachnids, and Their Relatives
(Photo courtesy Missouri Dept. of Natural Resources)
Among the most common insects and arthropods one runs into in Missouri caves are beetles,
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. Most troglobitic
insect species are noticeable smaller than their above ground counterparts. Scutigera, a
large arthropod which looks like it escaped a Grade B movie set, are well known from Missouri
caves. A large, fairly beautiful herald 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 page.
And collembola, a primitive, fungus eating insect, which are everywhere rotting stuff is to
2003 Jo Schaper.
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