Romance
is not without its pitfalls. A rebuff can be hard, but a welcome signal is not
always good news either. It may entail giving your all for the sake of passing
on your genes. Things are pretty tough if you’re a honeybee drone, but things
could be worse. You could be a praying mantis, a scorpion or one of those
spiders whose mate likes to relax afterwards, not with a cigarette, but with a warm
snack.
There
are several theories out there as to why some female spiders decide to munch on
their suitors. It has been suggested that it’s the female’s way of judging his
fitness for the job. Some say it’s just because they can as they’re aggressive
beasties and some say that it just how the express themselves when they
approve.
Where
there’s a theory, there’s scientists rushing to test it and in this case,
Berning et al from U Pittsburgh have
been out and about checking with denizens of the inner city, namely the clan Agelenopsi pennsylvanica (1, 2). This is
a funnel web spider and they got on their good side by tossing them crickets.
Once a rapport was established and they knew their ‘girls’, the researchers set
up a dating program.
The
‘guys’ were willing and able, but some of them paid the ultimate price for a
momentary dalliance and ended up staying for dinner with their cannibal mate.
A
great deal of data was gathered and pored over to check out those extant
theories. They didn’t appear to stack up. Size wasn’t important, that is male
or female body size so the egg situation was examined. There were no
correlations with number of eggs in a case, the size or the mass of individual eggs.
Aggressive
and hungry females were more likely to indulge in cannibalistic practices, but
the big correlation turned out to be the mass of the egg case that she produced
and the number of hatchlings that came from it. So in Pittsburg, if you are a
member of the A pennsylvanica persuasion,
eating your mate is good for your kids.
- http://www.sciencedirect.com/science/article/pii/S0003347212002916
- http://www.bbc.co.uk/nature/19072196
