Sex in the shallows

Well, here i is. Weather in this general area has been interesting, to say the least. Gradually built up to two weeks of over 43C – reaching 50C on a couple of days – then a cool change came through with a day or so of light rain. Seemed a bit weird at first – 20C felt positively freezing. Underclothes, track-suit and woollens.
Have, of course, moved camp and am now parked in the lee of a low bank of sand hills, 50 yards from the sea (Spencer Gulf). When first arrived not a soul in sight (well, one – if you count mine, but that could be a dubious concept). Sheer solitude, bliss.

Tide was out first thing this morn so, as is my wont, went for a wander in the shallows and rock-pools. Then .. ooo lookee, a blue swimmer crab sitting quietly in a rock-pool 4 inches deep. On closer inspection, noticed something odd. There seemed to be another, paler, shell underneath it. Um, think I, must be moulting ... No ... wait, I noticed a slight swirl of sand grains near the mouth of the underneath “shell”. Oooo lookee – two crabs sexing!

(click for biggeruns)

It looked like the larger, blue tinted “upper” crab was the male and the female crab was upside-down, flat on her back in the sand.
How she got there is unknown, as I didn't see whether she flipped herself over, or the male did it for her.

Apparently she opens her “gender flap” and the male backs in underneath it. It also looked as if there was some sort of slot underneath the carapace of the female, as the male apparently slides his gender flap into it, bringing their sex organs into close contact.

Have to say though that it wasn't the most “active” or exciting sexual coupling that have seen. Very little movement or activity for the 20 minutes or so that I observed and videoed. Only a tiny shrimp about 2mm long pruriently poking about. Occasionally the male would tickle his chin with the tips of his forelegs, and at one point the female reached out and grabbed a tasty bunch of seaweed to munch - while just laying back and thinking of Neptune?

While the pic shows the male with nippers in defensive stance, that was only because he was annoyed by me poking a camera up his nose (um, am I now a saline pornographer?) - mostly the nippers were tucked back in the “normal” position.

I didn't, unfortunately, capture any footage of their dis-engagement – since squatting on a sharp pointy rock for 20 minutes became somewhat uncomfortable, so went for a 5 minute walk to stretch my legs. By the time I returned, the male was sitting quietly about two feet away from the little sandy coloured female who seemed extremely stroppy when she spotted me – snapping her nippers together, almost leaping out of the water at me then hunkered down and almost vanished by throwing a couple of nipperfuls of sand over herself.

Perhaps she was a bit embarrassed, even though I saw no shame in the process – but then, I'll never really understand females .. heh.