The world is full of living creatures we can't see. They outnumber us, and they can be terrifying. The reason we can't see them is because they are too small, and that's a blessing, because many of them would give us unending nightmares. Getting a look at them from a view through a microscope may be upsetting, but this is nature. If they could see us, they might be frightened as well.
The creature shown at the top is a hydrothermal vent worm, ranked at #9, so you can imagine the horror that ranked above it. However, most are not all that ugly. They are included due to their danger to us, which may give you a case of the squicks, especially #2. -via Boing Boing
View the full list in the video clip below
Phantom midge larvae or glassworm
Common blue butterfly larvae