On the wildflower walk we came across two large millipedes that attracted lots of attention. The colorful specimen above is Apheloria virginiensis reducta (AVR). As usual, the bright yellow color is an aposematic warning to all potential predators of a poisonous or distasteful chemical. A recently discovered Apheloria polychroma comes in a variety of bright colors, advertising that it is toxic enough to kill 18 pigeon sized birds.
Like some other millipedes, AVR secretes cyanide compounds as a defense and can cause extreme irritation if you rub it in your eyes. Carrying around hydrogen cyanide as a weapon sounds like a risky strategy but millipedes get away with it because of their specialized mitochondria. They and many other millipedes have an oxidase that makes them resistant to cyanide.
Millipedes are the vultures of the plant world, patrolling the dark and damp world of rotting leaves and wood and recycling the debris, preparing it for the worms beneath.
This big boy is an American giant millipede, Narceus americanus, (NA) that can grow to 6" long but assumes a tight curl as soon as it is threatened. They live in forested areas, emerging from under leaf litter and logs to search out dead plants and animals. They molt during dry periods by burrowing into a log, sealing itself off, and shedding its skin.
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| Artistic posing for Wormboy magazine - Narceus americanus - Courtney Reece |
Even I could not make up NA's method of reproduction. "Its eggs are laid in a curious manner. The female places each one in a wad of chewed leaf litter, passes it back ward with many cooperating legs and shapes it within the rectum before placing the egg in a pile with others."* This teasing bit of information led me down an internet rabbit hole looking for the answer to the nagging question, "so how do they reproduce?"
I make a point of warning anyone handling a millipede that they should wash their hands. You would think any normal person would do that automatically but we naturalists are not anything near normal.
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| Apheloria gonopod - Derek Hennen |
If this is TMI ("too much information" for us olders), stop reading here.
Life History (from macalester.edu.)
"Millipedes have 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 species. 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 thereafter.
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 eggs.
Juvenile millipedes hatch, stay in the nest for a short period of time, and then molt their first shell about twelve hours after birth. 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 mature. It should be noted that larger tropical species might take up to ten years to become mature.
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 years"
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A good source of information on myriapods (millipedes and centipedes) is nadiplochilo.com.
* Spiders and Their Kin, Levi and Levi
