Monday, 8 August 2011

Mating Millipedes

Mating Millipedes, Ushongo Beach, July 2011
Whilst we were down at the beach we enjoyed seeing rather a lot of gian millipedes up to all sorts of things. Several decided it was definitely the mating season and thought's they'd show us some of the interesting things it takes to create a new generation of millipedes. So, here we go with some more wildlife interpretation...

What is it? Well,a giant millipede of some sort - I'm not exactly sure which one, but quite possibly a variety of Epibolus pulchripes, the Giant Red-legged Millipede. If you know better, please do let me know! And what are they doing? Well, that's certianly mating! As you can see, the male starts off by climbing on the back of the female and giving her a good tickling (at least, that's what it looks like). . In fact, he's busy preparing to mate - it's not easy with all those legs and, what's more, he keeps his genetalia in interesting places. In fact, his 7th pair of legs (millipedes have two pairs of legs per body segment, except for the first 7 segments where there's only one) are modified into what we call gonopods - gono, relating to gonad, and pod for leg. But the genitals themselves are in the 3rd segment (some species of millipede have two penises, which seems excessive), so the first thing the male has to do is depost a little package of sperm (the spermatophore) onto his gonopods.

Mating Millipedes, caught int he act.
Then once he's done that and the female is ready, she turns around and they go face to face for the finale (right). He now accesses her genital pores, as they're known (and on the female 3rd segment) and uses his gonopods to push the spermatophore into place. She then stores this sperm to fertilise her eggs, which in these giant species get laid in a nest in the moist soil under the leaf litter. She probably lays several hundred eggs, all fertilised from this one encounter, which in time hatch into baby millipedes, most of which are rather short and have just three pairs of legs, but will moult as they grow, each time adding more segments and more pairs of legs until they're mature.

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