Cymothoa exigua is a type of parasite that enters through fish's gills, eats their tongue, and then replaces it.
6
There's a phone app called RoboRoach that allows you to remotely control a cockroach through a chip that you to manually implant into the unwitting critter.
10
A banana slug can be 6-8 inches and their erect penis can be just as long. Also, their penises emerge from their heads. After sex, banana slugs eat each others penises.
17
Sniffologists have the job of sniffing armpits.
4