Image of the Day: Teeth

This jaw-like structure, called a signum, is complete with rows of “teeth” and sits within the reproductive organs of female Pieris rapae.

NATHAN MOREHOUSE

Female cabbage white butterflies house "teeth" within their reproductive organs that they use to break down males' sturdy ejaculate. “[T]he indigestible outer envelope of the spermatophore delays female remating, allowing males to monopolize paternity for longer,” the authors write in a report published in PNAS that describes the spermatophore's involved structure and the shrewd mechanisms female butterflies use to devour it.

According to The Atlantic, the scientists were only able to get through the spermatophores’ tough layers by “boiling them in concentrated sulphuric acid.” In lieu of acid, females chomp away using their, erm, teeth.

See C. Meslin et al., “Structural complexity and molecular heterogeneity of a butterfly ejaculate reflect a complex history of selection,” Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1707680114,...