I missed the theme? Why do some have red contacts and some don't?

I'm going out on a limb and assuming it's a twilight themed shoot...a very bland one

I thought it was a "girls have red contacts" thing but then Will has them and he's the only guy that does and idk why.

work itttTT

the girls and Will are meant to be spiders, hence the red contacts. There were an odd number of boys and girls, so Will was chosen to be a 'female of the species is more deadly than the male'
The actual shoot was for a commercial. This is a still-shot