I’m gonna preface this with, I’m not afraid of spiders. I’m cautious of spiders but not afraid. So let’s paint this beautiful picture.
BASED ON A REAL LIFE EVENT:
I was with the love of my life and his mother, trying to get his surfboard out of the shed. I was not aware how afraid he was of black widows. Armed with a bottle of insect killer, he attempted to get rid of two of them. After he sprayed one that was dangling and it fell, he stomped on it. Amused, I said, “Ya know, the venom goes through shoes, right?”
The look of absolute horror on his face was worth it but I couldn’t contain my laughter so he knew it wasn’t true.
So. Here’s what’s funny about this specifically. Most black widows give what’s called a dry bite. No venom is used. They *can* choose if and how much they want to inject. The venom is a neurotoxin that has its own name, latrotoxin. It’s actually pretty hard to get the spider to bite you. Poking the spider repeatedly, according to a study, resulted in them hiding, playing dead or flinging silk at the finger. Basically, you have to squeeze them to get them to bite you.
Females are the ones that typically cause problems when they bite. They have larger venom glands compared to males.
If bitten, in humans, localized pain happens about 5 to 10 minutes post bite. Sweating and goosebumps will happen. The pain may spread. Adrenaline increases blood pressure and pulse. The bites are rarely fatal unless you’re young or old or in someway sick.
Latrodectus is the genus that contains the black widow. There are 31 flavors. In the United States, there are four of them.
So. Black widows are known for eating their mates after mating. Well. It seems like that’s not entirely true in every species and every time.
Why would sexual cannibalism be a thing?
Well, some of the theories are:
- If another male sees a male in the web, he’s not going to attempt to mate with the female.
- Provides nutrition for the female to produce as many baby spiders as possible.
- The chance of finding another female to mate with is slim so he has fulfilled his life goal and should be snubbed out because he has no value anymore. Females store the sperm and typically only need to mate once.
According to recent research on Micaria sociabilis, the males are eating the females. This is linked to size and when the male was born. If the female was born in the spring and a summer male happens to approach, he will most likely eat her. This may happen because the female has a lower reproductive potential (as in not producing enough offspring or produce any offspring at all) or prey is limited. The summer males are known to be bigger and more aggressive. This is happening before mating.
There was another theory that suggested the cannibalism happens on accident sometimes. Because of sexual dimorphism. If the male is too small, he may send vibrations down the web that signal prey item rather than hey. hey hey. let’s make some babies.
TL;DR Don’t squeeze the black widows.
Until next time~
References
Size Matters – http://www.pri.org/stories/2013-05-06/size-matters-black-widow-spider-sexual-cannibalism
The Evolution of Sexual Cannibalism – http://ib.berkeley.edu/courses/ib160/past_papers/suttle.html
Wikipedia of course.
thepissedoffbiologist 