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EXPLORATION OF THE (ASIOMORPHA COARCTATA) ORTHOMORPHA COARCTATA FROM THE POLYDESMIDA FAMILY
Written By: Ashlyn
June 1, 2018
Millipedes are found almost anywhere, under rocks, in the dirt, or sometimes just lying on the ground. There is a large variety of millipedes, many colors, shapes and sizes. Orthomorpha coarctata, or better known as the flat-backed millipede in is the Animalia kingdom. Polydesmida is the largest of sixteen orders in Arthropoda and the class Diplopoda. Diplopoda directly means (doubled foot). An arthropod is an invertebrate animal, either spider, insect or crustacean. Polydesmida directly means (many bonds) referring to the many body segments on millipedes. Orthomorpha is the genus, meaning they regularly have twenty body segments. Species coarctata is distinguished by possessing longer and pointier keel. Many phenotypic traits of the polydesmida order include the flat back, often much color, the modified gonopods, the cyanide and ozopres along with the keels. Polydesmida is special in that they don’t have eyes. They have very sensitive antenna to feel for them. The dorsal plates and keels are often ornamented with ridges, tubercles and patches of color. Keel are the pieces of exoskeleton that stick out from the body of the insect and they act as protection. The Orthomorpha coarctata is regularly a dark black with yellow patches on the pieces of exoskeleton that stick out, these are what we call keels. This specimen had long, and sharp keel. The others that I observed had keel that were not as prominent and they were not as bright as o. Coarctata. For instance one had very long segmented legs and the other had short legs. Another had a round exoskeleton while the others were more rectangular and sharp edged. Polydesmida posses some special features that other species don’t. This order is able to release cyanide and other toxins through small openings under the keel. This cannot harm humans but it has the capability to blind animals for a short period of time. Also this type of millipede is able to roll into a ball much like a pill bug, this is the reason for the keel because they stick out. This species had 18 segments which is two less than they usually have, and it was 4 cm long. This is a relatively regular size and all of the specimen i found were within millimeters of each other.
The reproduction cycle varies between species. Some of the males deposit the sperm right into the female's genital openings, while others must first spin a web like structure called spermatophore. The male with either insert his gonopods directly into the female genitalia, and she will then have fertilized eggs. In the case that the male is too hairy, he spins the spermatophore which the female takes herself and inserts it into her own. She will lay the eggs in a damp spot. They have eight stages of growth, with each they molt, grow segments and grow legs. They will be juvenile until the with molt they are then considered an adult.
This species was collected under a rock with various types of bugs. It was near wild grasses and some pine trees. The others on this family were found in relatively the same places, although some were in dry places, while others were in dark and damp places.
The adaptations that were visible were, the keel, color and leg length. The o. Coarctata has much larger and sharper keel, it is darker and brighter in color and had medium segmented legs. The antennae were quite long, longer than some of the other specimen that were also collected. The other millipedes not this species, were not as rectangular in shape and they has shorter keel.

Sources
En.wikipedia.org. (2018). Orthomorpha coarctata. [online] Available at: https://en.wikipedia.org/wiki/Orthomorpha_coarctata [Accessed 14 May 2018].

M, R. (2018). External Anatomy of Polydesmida: Mating. [online] Polydesmida.info. Available at: https://www.polydesmida.info/polydesmida/mating.html

Keys.lucidcentral.org. (2018). Order Polydesmida. [online] Available at: http://keys.lucidcentral.org/keys/v3/TFI/start%20key/key/myriapoda%20key/Media/HTML/Polydesmida.html

En.wikipedia.org. (2018). Millipede. [online] Available at: https://en.wikipedia.org/wiki/Millipede