Narceus americanus

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Geographic Range

North American millipedes, including several sub-species, are found in the United States in all states east of the Mississippi River and nine states to the west (Minnesota, Iowa, Missouri, Arkansas, Louisiana, Nebraska, Kansas, Oklahoma, and Texas) and Canada (Quebec and Ontario provinces). This distribution is likely to change, however, as recent analysis of the taxonomy and distribution records of this species indicates that it probably represents a complex of multiple species. (Chamberlin and Hoffman, 1958; Hopkin and Read, 1992; Shapiro, 2010; Shelley, et al., 2006)

Habitat

These millipedes are terrestrial animals most often found in forests and agricultural areas in the soil-litter layer interface under rocks, boards, dead trees, and piles of moist dead leaves, and occasionally in moist animal corpses. They are also found in urban and suburban areas. Because their cuticles are permeable to water, they are restricted to habitats where humidity is high, otherwise they quickly become dehydrated. While different species of millipedes have been found from sea level up to snow lines of mountains, the elevation boundaries of this species are unknown. (Blower, 1985; Hopkin and Read, 1992; Ross, 2000; Shapiro, 2010; Williams and Hefner, 1928)

Physical Description

Although their common name, "millipede," implies that these animals have one thousand legs, the highest number of legs on record for an individual is 375 pairs; most millipedes have fewer than 50 pairs. North American millipedes have two pairs of legs attached to each body segment (except for a few segments at the anterior and posterior ends that have one pair). Centipedes, a closely related group of animals, can be distinguished from millipedes as they have only one pair of legs per body segment and venomous claws below their mouths. In general, bodies of millipedes are long and cylindrical, with many segments that are covered by a cuticle consisting of three layers. North American millipedes can reach up to 2.5 grams in weight and 10.2 centimeters in length. Individuals are mainly black, though the edges of their body segments show a range of colors including yellow, purple and pink. All millipedes have spiracles on their body segments, which are connected to their tracheal respiratory system and pairs of ozadenes (stink glands) connected to ozopores. These ozopores release a noxious substance, produced by the ozadenes, which contains large amounts of benzoquinones and may cause chemical burns. Unlike many millipedes, North American millipedes do not release hydrogen cyanide when threatened. Sub-species of North American millipede differ in the number and appearance of legs and body segments as well as color. Typically, males of this species have longer legs and antennae than females. (Blower, 1985; Chamberlin and Hoffman, 1958; Hopkin and Read, 1992; O'Neill, 1968; Ross, 2000; Shapiro, 2010)

  • Sexual Dimorphism
  • sexes shaped differently
  • Average mass
    2.5 g
    0.09 oz
  • Range length
    10.2 (high) cm
    4.02 (high) in

Development

Fertilized eggs are laid in a nest made of chewed up leaves and excrement that is made by the female. Although most millipedes lay hundreds of eggs at a time, the scientific literature indicates that each North American millipede nest typically contains only one egg. When they hatch, young have three pairs of legs and seven body segments. With each molt, they gain more body segments, legs, and other structures. North American millipedes molt many times throughout their lifetimes and size is directly related to age. (Blower, 1985; Galloway, 2010; Hopkin and Read, 1992; Ross, 2000; Schimming, 2011)

Reproduction

North American millipedes breed seasonally, beginning in the spring and early summer. Males spin a silken thread and emit pheromones in order to attract females. During millipede mating, males walk along females' backs in order to stimulate them. Females will raise their front segments, allowing males to pass a packet of stored sperm (spermatophore) to females. Some females mate only once, using stored sperm to fertilize all the eggs laid while others mate multiple times with other males. Males typically mate with several different females. (Hopkin and Read, 1992; Ross, 2000; Vattakaven, 2010)

North American millipedes' breeding season begins in the late spring/early summer and continues into autumn. Eggs hatch within a few weeks of being laid, although development times can shift with temperature changes. A female lays one egg in her prepared nest then wraps herself around the egg for brooding. Once the egg hatches there is no further parental involvement. Young millipedes take 1-2 years to reach maturity, with males usually reaching maturity first. (Blower, 1985; Galloway, 2010; Hopkin and Read, 1992; Ross, 2000)

  • Breeding interval
    North American millipedes may mate multiple times during their breeding season
  • Breeding season
    Late spring through autumn
  • Range number of offspring
    1 (low)
  • Range gestation period
    2 to 10 weeks
  • Range age at sexual or reproductive maturity (female)
    1 to 4 years
  • Range age at sexual or reproductive maturity (male)
    1 to 4 years

After mating, females may delay fertilization and protect the unfertilized eggs within their bodies. Females protect fertilized eggs by curling their body around them. (Galloway, 2010; Hopkin and Read, 1992; Ross, 2000; Schimming, 2011)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female

Lifespan/Longevity

North American millipedes typically live for several years. The longest recorded lifespan in this species is 11 years. (Blower, 1985; Hopkin and Read, 1992; Ross, 2000)

  • Typical lifespan
    Status: wild
    1 to 11 years
  • Typical lifespan
    Status: captivity
    1 to 11 years

Behavior

These millipedes are solitary and nocturnal. They hibernate during the cold, winter months and are most active at night. To avoid desiccation, North American millipedes initiate molting in moist places to reabsorb water through their cuticles. Millipedes are motile, using their multiple pairs of legs to move. Each pair of legs moves simultaneously, and subsequent pairs move in a wave-like motion down the axis of the body. They are capable of walking forward, backward, and side to side, as well as burrowing into soil. These millipedes may curl up if threatened, using their hard exoskeletons for protection, and also produce a noxious chemical to deter potential threats. (Blower, 1985; Hopkin and Read, 1992; O'Neill, 1969; Ross, 2000)

Home Range

There is no published information regarding the home range of North American millipedes.

Communication and Perception

North American millipedes sense their environment using their antennae, which can taste food, smell odors, feel, measure temperature, find water, and sense pheromones. Their Tömösváry organs, found at the base of the antennae, specifically measure humidity and possibly act as chemoreceptors. In addition, they have eyes on either side of the head which detect light and movement. Potential mates communicate using pheromones and silk trails. ("Millipede", 2009; Hopkin and Read, 1992; Ross, 2000)

Food Habits

Millipedes are detritivores and prefer decaying leaves, wood, and roots, especially if the decaying matter has bacteria and fungi, which may increase the availability of nutrients and palatability. They sometimes eat live vegetation but rarely animal tissue. Most are coprophages and eat their own feces, which allows them to digest nutrients that were not digested the first time. They use their mandibles to bite and crush food into small pieces. Salivary glands open in the foregut and secrete a lubricating solution. Microorganisms in the gut help to digest tougher material. (Blower, 1985; Hopkin and Read, 1992; Ross, 2000)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • algae
  • Other Foods
  • fungus
  • detritus
  • dung
  • microbes

Predation

Millipedes have a variety of defenses against predators. North American millipedes secrete a substance containing large amounts of benzoquinones that may cause dermal burns and discoloration. In addition to defensive secretions, millipedes will roll up in a tight ball to expose their hard exoskeleton as armor. In spite of these defenses, North American millipedes are prey items to many other animals, including ants, beetles, birds, centipedes, cockroaches, dogs, foxes, frogs, lizards, moles, opossums, raccoons, salamanders, scorpions, shrews, skunks, toads, and turtles. ("Macracanthorhynchus ingens Homepage", 2007; "North American Millipede", 2012; Blower, 1985; Hopkin and Read, 1992; Ross, 2000; Shapiro, 2010)

Ecosystem Roles

North American millipedes are important in their ecosystems as decomposers, stimulators of microbial activity, and are very important in the cycling of terrestrial calcium. While this species does not act as a predator or parasite itself, they do engage in mutualism with certain species of ants, providing sanitary services in return for protection from predators. This species is an intermediate host to parasitic worms such as Oligacanthorhynchus tortuosa (before its definitive host, Didelphis virginiana) and Macracanthorhynchus ingens (before its definitive hosts, which include dogs, foxes and raccoons), protists (Enterobryus elegans and Enterobryus euryuri), and nematodes (Rhigonema sp.). They are also commensals with some species of mites (Narceolaelaps americanus in particular) ("Macracanthorhynchus ingens Homepage", 2007; Hopkin and Read, 1992; Kethley, 1978; Misra and Lichtwardt, 2000; Ross, 2000; Shapiro, 2010; Williams and Hefner, 1928)

Species Used as Host
  • None known
Mutualist Species
  • Narceolaelaps americanus (Family Laelapidae, Subclass Acari)
Commensal/Parasitic Species
  • Enterobryus elegans (Family Eccrinaceae, Phylum Choanozoa)
  • Enterobryus euryuri (Family Eccrinaceae, Phylum Choanozoa)
  • Macracanthorhynchus ingens (Family Oligacanthorhynchida, Order Archiacanthocephala)
  • Oligacanthorhynchus tortuosa (Family Oligacanthorhynchida, Order Archiacanthocephala)
  • Nematodes (Rhigonema sp.)

Economic Importance for Humans: Positive

Millipedes are model organisms for studying arthropod physiology and segmentation. Their defensive secretions may also show promise as sources of new pharmaceuticals. (Hopkin and Read, 1992)

Economic Importance for Humans: Negative

These millipedes produce a substance that irritates and discolors human skin. In addition, they can do significant economic damage to root crops and are a nuisance when they swarm into homes and cover railroad tracks and roadways. (Blower, 1985; Hopkin and Read, 1992; Ross, 2000; Williams and Hefner, 1928)

  • Negative Impacts
  • crop pest
  • household pest

Conservation Status

This species has no special conservation status. (IUCN, 2012)

Other Comments

Millipedes first appeared in the fossil record 400 million years ago and are some of the first animals to have lived on land. It is hypothesized that these ancient species are the largest animals without backbones to have walked on earth. Modern forms appear in the late Paleozoic. While North American millipedes are currently classified as diplopods, Linnaeus classified them as apterate insects, Lamarck said they were arachnids, and others have called them worms or crustaceans. They belong to a diverse group with more than 10,000 described species. (Chamberlin and Hoffman, 1958; Hopkin and Read, 1992; Ross, 2000)

Contributors

Kelli Millican (author), University of Michigan-Ann Arbor, Jeremy Wright (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

chemical

uses smells or other chemicals to communicate

coprophage

an animal that mainly eats the dung of other animals

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mycophage

an animal that mainly eats fungus

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

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