Sunday 5 May 2013

Twig-like Feather-legged Spider

Image: Pen Araneae
The trees have eyes!

Twig-like Feather-legged Spiders are members of a genus called Miagrammopes and they look a bit like twigs. Of all things!

Image: Pen Araneae
These spiders spend their time with their long, cigar-shaped body and long, slender legs stretched out to their full length.

Image: Frank Starmer
Their front legs are often longer than their entire body...

Image: spiderman (Frank)

But by assuming the proper position, and with the correct green or brown colouration, they easily disappear into the surrounding foliage. Or at the very least succeed in looking nothing like a spider. Which is quite an achievement for a spider! It can't be easy for something with eight legs to make itself look like it has no legs.

Image: Robert Whyte
And if you take a very close look you may find your twig or stem staring right back at you! With four, shiny, black eyes... they probably think you look a bit odd, too.

Twig-like Feather-legged Spiders have a strange way of catching prey. It involves just ONE strand of silk!

Image: Pen Araneae
This is a spider web
One end of this strand is attached to a twig, while the spider grabs hold of the other end and pulls it taut. When a fly lands on the silk, the spider releases its grip and that single strand springs toward the twig on the other end, ensnaring the fly as it goes.

Video: Frank Starmer
Got to get that piece of string nice and tight!

Now the spider must go about immobilising their prey before they can tuck in. Here's the problem: Twig-like Feather-legged Spiders are in the family Uloboridae, the Hackled Orb Spiders. This means two, big things:

First, that one strand of silk used to catch the fly wasn't sticky, because Hackled Orb Spiders don't produce sticky silk. "Hackled" silk is sort of woolly and fuzzy, instead. It traps prey by snagging them, not sticking them.

Image: Robert Whyte
Comb on the hind legs
This is where the Feather-legs come in. Spiders that produce this kind of silk use special spinnerets called a cribellum. It's a bit like a sieve covered in thousands of tiny holes. The silk comes out of these tiny holes and is then combed (or hackled) into strands by a kind of comb on the hind legs.

So when I said ONE strand of silk, I meant one strand of silk made up of THOUSANDS of tiny strands of silk.

Image: plj.johnny/潘立傑
Munching on a little something
The other thing about Uloborids is that they are non-venomous. They have NO venom and NO venom glands! And this time I really mean it. They don't have thousands of venom glands which all add up to nothing in some weird way.

So how will our Twig-like Feather-legged Spider eat her meal in peace? The answer is silk. Lots and lots of silk.

Video: sigma1920
She could've made herself a nice cardigan out of all that!

Uloborids spend a long time smothering their prey in huge amounts of silk. There are some who can spend an hour cocooning their prey in over 100 metres of silk! This means their prey is not only well and truly cocooned and entombed, but it's also suffocated and crushed.

Most spiders would now put on their napkin and inject digestive enzymes to prepare their meal. Uloborids don't do this, they simply slather and slobber those enzymes all over their squished up food parcel and then slurp up the nastiness. Turns out poison and injections are the polite way of doing things.

So much for death... what about life?

Image: Frank Starmer
A mating pair?
Aside from a twig, this looks like one, really long Miagrammopes. It actually seems to be two of them. The photographer, Frank Starmer, wonders if they are mating. And it would make a certain sort of sense if they were. The sort of sense that comes when you totally immerse yourself in the strange, alien logic. Like when I heard Neil deGrasse Tyson wonder why Batman can't fly even though he has a cape.

Image: 小工友
Mother and egg sac
And this appears to be a proud mother with her twig-like egg sac.

So it seeme Twig-like Feather-legged Spiders are twig-like at conception, twig-like in the egg and twig-like throughout life. The twig-likeness only stops when it's time to kill, which must be extremely annoying for all those insects that get killed and eaten. If only it could act like twig just this ONE MORE TIME! Oh, well.


TexWisGirl said...

just when you think you know a spider... funky!

Joseph JG said...

It's always nice when they're even weirder in detail!