Mean Genes
Who’s your daddy?
Following
copulation, some male worms seal the female’s vagina with a plug of cement. Males
also seek out and force themselves on rival males, cementing shut their
rivals’ sperm tubes.
In other species,
a male will inject sperm directly into a rival’s body and the sperm swim down
into the victim’s testicles. When the victim has sex, he fathers babies with
the aggressor’s sperm.
Before
ejaculation, a male damselfly uses his shovel-shaped penis to scoop out the
female’s vagina—removing sperm from previous lovers. After sex, the male
black widow spider breaks off his penis inside the female, preventing her
from ever mating again.
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