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:

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.

Isopods

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.

Amphipods

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

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.

Cave Planarians

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

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 be found.

2003 Jo Schaper.