Wednesday, April 13, 2011

Now This Is Too Scary...!

Sometimes Mother Nature is a hard task master!

In order to insure the survival of the species, she will go to extremes! At least, it seems a bit extreme to us! I reckon it makes perfect sense to the creatures involved in the plan!

Sort of makes me wonder just what Mother Nature might have in store for us, ya know?

Male wolf spiders cannibalise older females, scientists in Uruguay have discovered.

In several species, female spiders are known to eat males, but this is the first time biologists have seen the roles reversed in the wild.

The male spiders were observed mating with virgins and eating older, less reproductively successful females.

Researchers suggest that harsh habitats force males to prey on females for food.

Their findings were published in the Biological Journal of the Linnean Society.

The species in question, Allocosa brasiliensis, is a nocturnal wolf spider found in South America's sand dunes along riverbanks and the Atlantic Ocean coast.

The researchers were studying the species because its status is considered an indicator of the health of coastal habitats.

After observing a male spider eating a female in the wild, Dr Anita Aisenberg and her team from the Clemente Estable Institute of Biological Research, Montevideo, set out to find an explanation for the behaviour.

"In spiders in general, females are larger than males and they are the selective sex, while males are small rovers that go out and look for potential sexual partners," explained Dr Aisenberg.

In A. brasiliensis though, researchers found that the males were unusually dominant.

Although sexual cannibalism has been widely documented in spiders, the researchers were surprised to see male A. brasiliensis eating females.

"This is not only the first report for spiders, but also this is extremely rare for the animal kingdom," Dr Aisenberg told the BBC.

Researchers observed the male wolf spiders waiting in their burrows for visiting females looking for a mate.

"Males mated more frequently with virgins with high body condition, as a way of ensuring a future successful progeny," said Dr Aisenberg.

"In this species the first egg sac is the most successful in [terms of the] number of eggs, so with virgins they ensure this first brood."

"And females with better body condition will provide more eggs and, consequently, more sons and daughters."

Older females, and those with lower body condition, were in for a nasty surprise as males took advantage of them for other needs.

In what the researchers described as an "extreme sexual choice", the male spiders selected whether to mate with females or eat them; a choice that appeared to be based on their mating potential.

According to Dr Aisenberg, the environment in which the spiders live may have moulded their unusual sexual behaviour.

"The habitat of A. brasiliensis can be considered harsh with extreme temperatures, strong winds, scarce refuges and very unpredictable in prey abundance," she said.

"[Males] cannibalise females of low reproductive value and take advantage of them as prey, and mate only with the females that ensure them high reproductive success."

I guess the battle of the sexes is a lot more deadly in the animal kingdom than it is with humans! Still, one of the scariest things about this is that these males are like the Zombies of the spider world! Food must really be getting scarce in the wonderful world of creepy crawlers!

Let's get some fresh coffee and sit outside for a bit! Keep an eye out for those bad boys crawling around, OK?


Anonymous said...

That's freaky HJ, and I'm a lot closer to Uruguay than you are.


HermitJim said...

Hey AV...
I'm glad it's you that's close and not me! I don't like spiders...and I particularly don't like spider cannibals!

I'll let you keep them over there!

Thanks for coming by this morning!

Bustednuckles said...

Watch out, you Cougars!

chinasyndrome said...

Why hello! Come in.Where is that A-1 sauce. Jim the older ones are kinda tough but they taste like chicken. Spiders yuck I seen em make grown men squeal like little girls.


Mechanic in Illinois said...

I think we should put a colony of these spiders in everyone's bathroom. That way if you ever get constipated one of those spiders could run up your leg and I'm sure you wouldn't have any trouble going at that time. Thanks for the story and have a great Wednesday.

Ben in Texas said...

Mean ugly looking thing!!! . I'm not real arachnophobic even thought I have been bitten. In fact I try to leave my big ole Wood spider,and the other harmless ones alone outside, they eat a lot of bugs and grasshoppers.

Momlady said...

Glad it's not that way in the human world or I'd be a goner.

edifice rex said...

You and me both Momlady! lol!! yeeeeeck!!

JoJo said...

I like it the other way around. But yea I would be a goner too. LOL
Well I am heading for the hills on Sunday Dr. gave me the go ahead YIPPEE.
But you know I will be around for the morning coffee. :D

HermitJim said...

Hey Busted...
I have a feeling that if these bad boys got really hungry, anything would be fair game!

Thanks, buddy, for the visit today!

Hey China...
I'm sure that I would make some squealing sounds if I saw any of these big guys around!

Be my luck, he'd probably eat my cat!

Thanks, my friend, for dropping by today!

Hey Mechanic...
As long as somebody didn't run through the house before their job was finished, leaving a might work OK!

Sort of like a bunch of grand daddy long legs in the corner of an outhouse, ya know?

Thanks for coming by today, my friend!

HermitJim said...

Hey Ben...
I would try and tell them, you leave me alone and I'll leave you alone!

They might not hurt you, but they could probably make you hurt yourself!

I just don't like spiders at all!

I really appreciate the visit this morning!

Hey Momlady...
Can you imagine all the damage a human with this same attitude could do?

Come to think of it, we might have a few of these types around!

You have a great day, and thanks for coming by today!

Hey EF...
Somehow, I can't see you as being afraid of these rascals at all!

I figure you would spit in their eye, and then order them off the property!

I really do appreciate you coming by this morning, my friend!

Hey JoJo...
Glad you are getting gone to the Summer place, sweetie! I know you are ready!

You just make sure you show up for our coffee each morning, OK?

Thanks for coming over, dear!

tffnguy said...

It isn't uncommon for king cobra males to kill and eat females if they won't have sex with them or if some other male has already gotten to them then the males may fight, but won't bite each other. If the snake that mated with the female wins the fight then the female lives and if not then the winner kills and tries to eat the female if they aren't too large. I suppose this has to do something with survival of the fittest also?

HermitJim said...

Hey Tffnguy...
Hope I'm never close enough to witness all this going on!

I have a feeling that, given a choice, I would be moving away in high gear!

You probably have quite a few good sized spiders out at your place! They do like the desert , at least some of them do!

Thanks, buddy, for coming by today!

Anonymous said...

So strange!
But really interesting too!

Have a great day now!

HermitJim said...

Hey Christer...
What are the chances of finding one of these nasty guys there in Sweden?

Around your house, I would imagine the many birds you have pretty much take care of the bugs (including spiders)!

Thanks for the visit this morning! said...

I neither like nor dislike spiders...kinda ignore 'em when possible but this hunker is ugly with a capital U!
Momlady, I don't think u need worry but mayhaps this is why I don't want males around!!!