Documenting Diversity at the Katharine Ordway Natural History Study Area
Parajulidae spp., Millipede
This organism has no common names.
***NOTE: Due to the lack of literature and description of the order
Julida, this page will focus primarily on class Diplopoda as a whole,
but with some information about the order Julida. (Denoted by *)
*This organism was first characterized as a diplopod
based on its possession of two pairs of walking legs on each segment2.
Its many segments also helped in discerning its identity. This
classification was narrowed down to the order Julida in looking at the
organism’s first legs, seventh segment and cylindrical shape5. Its
first set of legs appeared larger and thicker. This is because males of
the order Julida posses their gonopods on this body segment4, 5.
The seventh segment of the millipede has modifications that denote
copulatory organs, which are also definitive of the order Julida. The
very small size of this specimen also aided in its classification,
because Julida millipedes are some of the smallest of the cylindrically
shaped millipedes in North America. Millipedes of the family
Parajulidae are the only members of order Julida known to inhabit
Minnesota, as well. With that, the collection site allowed the taxonomy
to be classified down to the family level8.
Although millipedes of the order Julida, family
Parajulidae are the most common millipedes in the Western Hemisphere,
there is very little literature on them, so the classification of this
organism could only confidently be narrowed down to family5, 8.
Millipedes generally live in habitats with lots of
vegetation and damp soil so they can safely burrow during the day, as
they are more active at night. These habitats include area under leaf
litter, stones, and sometimes underneath the surface of the soil.
However, some millipedes are known to live in drier habitats, like
deserts or up in the canopies of trees4. Certain millipedes have been
found inside of dead and decaying animals, but it is not known if they
were seeking shelter or nutrition3, 4. Millipedes are seasonal
organisms, and some hibernate through winter in giant colonies. In
general, they are most abundant in fall and spring due to better
Millipedes are recognized as detritovores, meaning
they feed on decaying material. They usually feed on decaying plant
material on the floor of vegetation rich habitats. These animals prefer
plant matter high in calcium content that has been decaying for quite
some time. In addition to being detritovores, millipedes also obligate
coprophages. This means they can survive for a short amount of time by
feeding on their own feces. Millipedes also serve a very important role
for the soil content in their habitats. When they break up the decaying
leaf matter, they increase the surface area that the decaying matter
covers, thus spreading out potential nutrients. Scientist F. H.
Colville once said that millipedes, in a given environment, have the
ability to make about two tons of fertilizer per acre per year1. This
shows how millipedes can contribute to their habitats by making the
soil more nutrient rich, so plants have the potential to grow more.
Millipedes exhibit many interactions with other
organisms, including suffering from parasitism. Diplopods in some areas
of Australia are subject to mite infestation. However these mites use
the millipedes as a means of transportation, not nutrition1. Some
millipedes are able to avoid some dangerous encounters with other
organisms through their defense mechanisms of toxic chemical secretion.
When they feel threatened, the secrete chemicals that are usually very
foul smelling, in order to protect themselves and keep predators or
parasites from attacking them1. This is a very valuable defense
mechanism for their survival, but also comes at a high cost of energy
in synthesizing the toxic chemicals.
Millipedes posses special reproductive organs inside
of the segments above some of their legs. The actual location of the
organs depends on the species. These organs, called gonopores, are
referred to as secondary sexual organs when they are inside the second
or third segments, and primary sexual organs when they are inside of
the seventh segment. Before a male millipede mates, he needs to
transfer his gonopore to his seventh segment. Female millipedes also
have specialized gonopores, but for a more particular purpose. Females
of each species of millipede have different gonopores in order to
prevent hybridization between species1. Some females mate once per
mating season, and others mate multiple times per season, depending on
the species. Millipede reproduction relies on courtship before the
female allows the male to mate with her. Fertilization occurs
internally, and is generally accompanied by long periods of clasping
shortly thereafter2. Once her eggs have been fertilized, a female
burrows into the soil and creates an underground nest. Females lay
between a few hundred and two thousand eggs, depending on their size
and health1. Life after reproduction also varies greatly between
species. Some live for up to a year after laying eggs, and others are
semeparous, and die shortly after laying eggs1.
Juvenile millipedes hatch, stay in the nest for a
short period of time, and then molt their first shell about twelve
hours after birth1. Millipede development involves seven stages of
growth. During each one of these stages the millipede re-molts its
shell and adds segments. It generally takes about one year for
millipedes complete the seven-stage cycle, and shortly after they
become sexually mature2. It should be noted that larger tropical
species might take up to ten years to become mature1. After reaching
sexual maturity, millipedes stop growing and molting new shells. The
life spans of millipedes vary from species to species, depending on
size and environment, but in general, these organisms live for two to
five years. However, some can live over ten years6, 7.
There are about 10,000 species of identified
millipedes that are widely distributed around the world today, except
in polar regions6. Every continent has its own population of
millipedes, excluding Antarctica8. Millipede species are locally
distributed and often stay within a few square miles of their
birthplace. Many genera are localized to one continent, as well2. Thus,
many species of millipedes are endemic to their birthplaces. In
comparison to temperate areas, there are more species of millipedes
found in tropical areas, and these tropical millipedes can grow much
larger, as well.
*Millipedes of the order Julida are widespread
compared to other orders. Julida millipedes are usually only found in
temperate areas. They are native to west Asia and Europe, but are also
widespread in the Western Hemisphere. Millipedes of family Parajulidae
are the most common millipede in North America, and have been found in
habitats stretching from Alaska to the Atlantic Ocean, and from Canada
This organism was collected at the Katherine Ordway
Natural History Study Area located in Inver Grove Heights, Minnesota.
It was collected under leaf litter directly adjacent to two trees. The
habitat was very damp, and the specimen was found tightly coiled around
a twig. Below are pictures of the collection site.
1. The Earth Life Web http://www.earthlife.net/insects/diplopoda.html
2. AcessScience by McGraw-Hill
3. Coleman, David C., D. A. Crossley, and Paul F. Hendrix. Fundamentals
of Soil Ecology. Amsterdam: Elsevier Academic, 2004. Print.
4. Hopkin, Stephen P., and Helen J. Read. Biology of Millipedes. Oxford: Oxford UP, 1992. Print
5. Levi, Herbert Walter, Lorna Rose Levi, Herbert S. Zim, Nicholas
Strekalovsky, Jonathan P. Latimer, and Karen Stray. Nolting. Spiders
and Their Kin. New York: St. Martin's, 2002. Print.
6. Arizona-Sonora Desert Museum. http://www.desertmuseum.org/books/nhsd_centipede.php.
7. Oklahoma Cooperative Extension Service. http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2295/EPP-7316web.pdf
8. Milli-Peet. http://www.fieldmuseum.org/research_collections/zoology/zoo_sites/millipeet/pdfsFullarticles/MP10Table3.pdf
Compiled by Garrett Salzman.
Biodiversity & Evolution (BIOL 27), Professor Sarah Boyer. Spring 2010.
Specimen collected at Macalester College's Katherine Ordeway Natural History Study Area on April 15, 2010.