Wednesday, 14 March 2012

Crab-like Spiny Orbweaver

Image: Sam Fraser-Smith via Flickr
It's Gasteracantha cancriformis again! We were first introduced to her at the Gasteracantha party, so let's take the opportunity to find out a little more about her.

Image: Larah McElroy via Flickr
You should be glad of those scientific names because this spider goes by a huge number of common names, many of which equally refer to all sorts of other spiders. Names like Crab Spider, Spiny-backed Orbweaver, Jewel Spider, Smiley Face Spider and other variants.

Image: bob in swamp via Flickr
Gasteracantha means "thorn belly" and cancriformis means "crab-like", so that seems pretty good to me. She's also an orbweaver, building those beautiful, spiralling orb-webs to catch her prey.

Image: squamatologist via Flickr
She can be found across southern USA, Central and Southern America and several Caribbean Islands. This, along with being so unforgettably eye-catching is probably why she has so many common names. She measures only a little more than 1 cm (0.4 in) across and even less in length, but if you see this lady you won't soon forget her!


G. cancriformis is actually highly variable in colour. You always see those 6 spines but they can be red or black, and the rest can be white, red, orange or yellow. This meant that scientists described her under dozens of scientific names, too! Those guys had to reach for their microscopes to sort it all out.


Of course, this is all the female. Males are tiny at just 2 or 3 mm long, with drab colours and 4 or 5 little stubs rather than the female's magnificent spines. They can sometimes be seen hanging from strands near the female's web.

Image: key lime pie yumyum via Flickr
When the time is right, he will carefully approach her, rhythmically vibrating the web and ensuring he gets seen. It's kind of like what they tell you about bears. How you should make a bit of noise so that you don't take them by surprise. Bears don't do the next bit though.

Image: cwulmer via Flickr
Once he is accepted, the female straps him down with silk and they copulate for about half an hour. Kinky! He seems to be really into that sort of thing because he'll stick around when they're finished and they could end up doing it repeatedly.

Image: cwulmer via Flickr
He will be dead within the week. I hope he enjoyed himself! The female soon makes an egg sac with some 200 eggs and hides it under some leaves. Then she promptly dies.

Image: Cletus Lee via Flickr
The tiny spiderlings that emerge must disperse and create their own, tiny webs. Both males and females will be mature in around a month, and both are likely to be deceased within a year. It's a fleeting life, but a beautiful one. And it gets really sexy at the end.

3 comments:

Crunchy said...

These things look like video game enemies. Just hanging around, waiting for a plumber to come by so they can drop down and murder him with their spikes.

TexWisGirl said...

just flipping cool!

Comment1 said...

@Crunchy: They do! I could imagine the different colours having different strengths and attacks. The orange one MUST shoot fire.

@TexWisGirl: Darn right!

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