Subclass

CHAPTER

phylum class subclass order monotypic order suborder family

PHYSICAL CHARACTERISTICS

Pauropods are very small, measuring only 0.019 to 0.078 inches (0.5 to 2.0 millimeters) in length. Their long slender white or brownish bodies are usually soft and flexible, but some are covered with relatively thick plates. The small head is directed downward. Their chewing mouthparts are small, weak, and made up of two sets of jaws. The first set of jaws has curved teeth that look like a comb. The second pair is joined together to form a flaplike structure. They lack eyes. The antennae (an-TEH-nee), or sense organs, have two branches. The body is twelve-segmented and has eight to eleven pairs of legs, one pair per body segment. There are usually only six plates across their backs, but some species have twelve. Like millipedes, the reproductive organs are located toward the front of the body on the third segment. The last segment has a special plate. The size and texture of the plate is used to distinguish different species.

GEOGRAPHIC RANGE

They are found on all continents except Antarctica. There are about seven hundred species known worldwide. The pau-ropods of the United States and Canada are so poorly known that it is not possible to give even an approximate number of species found in these countries.

HABITAT

Pauropods live in a variety of habitats and are most common in the upper 7.8 inches (200 millimeters) of soil. They are of ten found in moist soils under rocks, wood, and clumps of moss.

DIET

The foods of most pauropods are unknown. Some species eat mold or suck fluids from the rootlike structures of funguses. One species is known to eat the tiny hairlike structures on plant roots.

BEHAVIOR AND REPRODUCTION

Populations of pauropods are usually small and widely scattered, but the populations of some species can reach the thousands in both wild areas and agricultural fields. They move through the soil to follow changing moisture levels. Since their bodies are soft and not built for burrowing, pau-ropods follow roots and crevices deep into the soil as they search for moisture. Most species run very quickly, usually in fits and starts. These species usually change directions with ease, but a few are not so agile. Nothing is known about how they communicate with each other or whether or not they maintain territories.

Both males and females are usually required for reproduction. A few species are known to reproduce by parthenogenesis (PAR-thuh-no-JEH-nuh-sihs), where the larvae (LAR-vee), or young, develop from unfertilized eggs. The eggs go through a short pupalike stage before they hatch. A pupa (PYU-puh) is the life stage between larva and adult. In one group of pau-ropods the larvae hatch with three pairs of legs. With each molt, or shedding of the exoskeleton, or hard outer covering, the total number of legs changes to five, six, and eight pairs. In all other pauropods the hatching larvae start with six pairs of legs.

PAUROPODS AND PEOPLE

Pauropods are small and secretive animals that are overlooked by most people, even trained scientists. One species (Saintpaulia) in the Netherlands is known to damage greenhouse cuttings, but all others do not impact people or their activities.

YOU NEVER KNOW UNTIL YOU LOOK

Since 1866 more than seven hundred species of pauropods have been described, but there may be two thousand to three thousand species awaiting discovery, possibly more. In 2002, a retired high school teacher from Sweden, the world's only authority on the group, paid a visit to Great Smoky Mountains National Park. Only five species of pauropods were known from the park, but in just three weeks he found at least forty-four species, twelve of which were new to science.

CONSERVATION STATUS

There are no pauropods considered endangered or threatened. They are so poorly known that little thought has been given to their conservation.

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