The secret life of millipedes

Aug 21, 2011
This is an Oxidus gracilis gonopod. Credit: Giuseppe Fusco

Male adult helminthomorph millipedes usually have one or two pairs of legs from their seventh segment modified into sexual appendages. These specialized gonopods are used as claspers to hold the female during mating or to transfer sperm. New research published in BioMed Central's open access journal Frontiers in Zoology has looked in detail at millipede development and the internal reorganization needed to produce functional gonopods.

Millipede puberty is a radical affair. The change in function from leg to gonopod can occur within a couple of moults, during which the millipede typically adds more segments to its length and sheds its too-small skin. These animals are difficult to study with standard techniques due to their hard , because from their stink-glands interfere with most conventional microscopy preparation techniques. However, using confocal laser scanning microscopy, researchers from the University of Padova were able to investigate this dramatic transformation throughout the relevant moults.

Conversion of to gonopods first requires regression of the legs in segment VII into tiny primordia. The primordia then develop into gonopods and the exoskeleton rearranges, producing a gonopodal sac which shelters the base of the gonopods and a U-shaped apodeme, to act as an anchor point for the bulky muscles required to operate the gonopods. In three species out of the four investigated, some of these muscles, both protractors and retractors , extend to attach to skeletal structures on the flanking segments, VI or VIII, and another muscle (abductor) stretches across the pair of to move them apart in a pincer movement.

This is a specimen of Oxidus gracilis. Credit: Giuseppe Fusco

Dr Leandro Drago, one of the team who performed this work, said that, "Conversion of legs into specialized gonopods via non-systemic metamorphosis is not a simple matter of changing the appearance of the legs and adding spines. The exoskeleton and muscle reorganization of segment VII during sexual development forces the nerve cord to become displaced and a causes a reduction in the volume of digestive tract through this segment."

Dr Drago continued, "This may well impact the amount of food an adult male millipede can eat and may be why they appear to lose weight when sexually mature. Males of some species of millipede can revert back into an immature stage (periodomorphosis) which may be an adaption to prevent starvation."

Explore further: Male monkey filmed caring for dying mate (w/ Video)

More information: Structural aspects of leg-to-gonopod metamorphosis in male helminthomorph millipedes (Diplopoda), Leandro Drago, Giuseppe Fusco, Elena Garollo and Alessandro Minelli, Frontiers in Zoology (in press) www.frontiersinzoology.com/

Related Stories

Millipede feared extinct is found

Jul 31, 2006

U.S. biologists say Illacme plenipes, a millipede with up to 750 legs that was last seen 80 years ago, has been found in California.

Robotic exoskeleton replaces muscle work

Feb 08, 2007

A robotic exoskeleton controlled by the wearer's own nervous system could help users regain limb function, which is encouraging news for people with partial nervous system impairment, say University of Michigan researchers.

Evolution in reverse: insects recover lost 'wings'

May 05, 2011

The extravagant headgear of small bugs called treehoppers are in fact wing-like appendages that grew back 200 million years after evolution had supposedly cast them aside, according to a study published Thursday ...

Sex is thirst-quenching for female beetles

Aug 28, 2007

Female beetles mate to quench their thirst according to new research by a University of Exeter biologist. The males of some insect species, including certain types of beetles, moths and crickets, produce unusually large ejaculates, ...

Study: Long legs are more efficient

Mar 12, 2007

Scientists have known for years that the energy cost of walking and running is related primarily to the work done by muscles to lift and move the limbs. But how much energy does it actually take to get around? Does having ...

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Vendicar_Decarian
not rated yet Aug 21, 2011
Those dirty little millipedes. Sex is evil, and funding for this research is about to be cancelled by Da Gubderment.

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Finnish inventor rethinks design of the axe

(Phys.org) —Finnish inventor Heikki Kärnä is the man behind the Vipukirves Leveraxe, which is a precision tool for splitting firewood. He designed the tool to make the job easier and more efficient, with ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.