Here are some rather freaky images of Macropinna microstoma, a deep-sea fish with a transparent head. Its eyes can rotate within this transparent shell allowing it to see the water above, as explained in this fascinating video from the Monterey Bay Aquarium Research Institute.

This has to be one of my favorite MetaFilter posts. The community links to all manners of amazing cephalopods, highlighting the beautiful blanket octopus which I had never heard of.

These species have an extreme degree of sexual dimorphism. According to the Melbourne Museum, “there’s no other non-microscopic critter that has such a significant size difference between the male and female.” Measuring only 2.4 cm long, the male blanket octopus is incongruously smaller than the female who can grow to over 2 m. This means that the female can be 100 times larger than her mate, and up to 40,000 times heavier.

More pictures at Tree of Life.