Sunday, 20 July 2014

Dancing White Lady Spider

Image: James Anderson
Leucorchestris arenicola
Arrrgh! It's a g-g-g-ghost!

Oh wait, no it isn't. It's a great, big spider. Phew!

...

Aaaaarrrggh!

Image: James Anderson
It's strange... You hear about the White Lady of the Desert and you expect it to be the story of a young, German beauty who lived with her father, the commissioner of Deutsch-Südwestafrika. There, in the desert heat of south west Africa, she fell in love with a promising, young administrator blessed with striking good looks and great talent. "That guy can administrate the hell out of anything", say his fellow administrators with a twinge of envy. "I wish he would administrate the hell out of me, if you know what I mean", say all the German wives and daughters with even more envy.

The beauty and the administrator are soon engaged to be married, but tragedy strikes.

On the eve of the wedding, the beauty is too excited to sleep. She drinks a sleeping draught from the chemist, but there's been a terrible mistake. It's not a sleeping draught at all, but a very powerful amphetamine. To the rhythmic beat of her own racing heart, she dances. She dances out of bed. She dances out of her bedroom. She dances down the hall, out of the building and into the moonlit desert, never to be seen again.

Never, that is, unless you believe the stories. The stories that speak of a young woman in a wedding dress, who dances across the bleak desert sands on moonlit nights. Sadness clouds the features of all who speak of The Dancing White Lady. The White Lady of the Desert.

Image: Dflinkmann
Aglow
But it's a great, big spider, instead!

And with a legspan that can reach over 10 cm (4 in), it certainly is pretty big. And that's not uncommon among members of the Huntsman family. Yes, the White Lady is a Huntsman (Huntsgentleman?). They're also pretty! Aren't they? I think so. With their lovely, white colour they can fair glow in the hot sun of their home in the Namib Desert. Oh, and Namibia really was a German colony in the late 19th to early 20th century. They called it Deutsch-Südwestafrika, or German Southwest Africa, because it's right down in the south west of the continent.

Image: James Anderson
Burrow
The Namib is really, really hot, so White Ladies don't actually strut around under the sun, even though they'd look really nice if they did. Instead, they spend the day hidden in burrows constructed out of silk and sand. They even build a little lid for it so they can be completely hidden from view.

White Ladies are active in the cool nights. They can catch food just like a trapdoor spider, waiting around in their burrow until prey wanders close enough for them to burst out of the ground and snatch it up. Trapdoor spiders typically lay tripwires of silk to alert them of the presence of nearby prey, but White Ladies don't do that. They can feel the vibrations of footsteps directly through the sand. I guess a near total lack of moisture, leaves and plants has its advantages!

Image: James Anderson
Underground burrow dug up. Also there's a spoon in it
White Ladies will also emerge and walk around in search of insects and lizards to feed on. They will usually only wander up to 5 metres (16 feet) away from their burrow. However, there are times when an adult male will travel significantly further.

Obviously it's all about reproduction! When a male is sufficiently frisky, he may walk a distance of over 100 metres (330 ft) in search of a mate. When he comes across a female's burrow, he uses his legs to carefully drum a rhythm to her. It's basically spider Morse code for "would like to administrate, if you know what I mean. Please don't eat me." He needs to add that last bit because while he has a bigger legspan than her, she's that little bit heavier than he is.

It's this toe-tapping which earns them the "Dancing" part of their name. It just so happens that it's the male who does it in order to avoid the decidedly unladylike murderous aggression of the female.



Video: BBCWorldwide

If he does get eaten, then all his problems are over. They haven't been solved, but they are over. If he's still alive, regardless of whether he has successfully mated or not, he now finds himself a long way from home and shrouded in darkness.

In his search for a female it's likely he will have wandered hither and thither in a long, circuitous path. Now, on his way back, he's able to march in a straight line all the way home. He doesn't do it through sheer memory as if he's drawn a map of his adventure in his brain. Indeed, if you blind a White Lady, she'll get completely lost if she wanders as little as 50 cm (2 ft) away. Scientists did in fact blind a whole bunch of White Ladies to find this out.

Image: James Anderson
It turns out any White Lady Spider, including females and juveniles who have only nipped out for a bit of hunting nearby, need to use their eyes to get back home. They use starlight, but the stars are so faint and their vision so poor that they have to stop every few seconds and wait until sufficient light hits their eyes for them to see the star it came from.

So Dancing White Lady Spiders navigate the midnight desert by looking at the stars. I knew there was some romance in there somewhere!

4 comments:

TexWisGirl said...

she's quite beautiful.

Porakiya Draekojin said...

I agree, they are quite beautiful. Also, I must point out that they look just slightly transparent in the moon light, giving them a ghost like feel. The way they move also looks a little like they're dancing.

Crunchy said...

I would absolutely prefer she be a ghost rather than a spider. At least she's not a spider ghost. ...wait... is she? Is that a thing?

Joseph Jameson-Gould said...

@TexWisGirl: I'm glad you agree!

@Porakiya Draekojin: Yes! They're gloriously spooky!

@Crunchy: Spider ghosts?! I do hope so!

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