It all started with a story about the Sex Lives of Barnacles from Discovery News. Barnacles, really? How exciting could that be? Well for one, they have the largest penis relative to their body size! But even more exciting, scientists recently confirmed that intertidal gooseneck barnacles (Pollicipes polymerus to their friends) capture sperm directly from the water. Up until now, it was thought that all crustaceans copulated directly in some way.
On the left: A stalked barnacle with a relaxed penis (marked with arrow); On the right: Erect barnacles releasing sperm into water. Image:courtesy of Discovery.com
Unlike the uncharacteristically stand-offish approach taken by barnacles, the video below shows an unusually close encounter between a pair of deep-sea squid. It's very rare to see a pair of squid mating, and the males often use a modified arm instead of a penis. If you like the choreography, check out the 'disco clam' video by New Scientist TV.
But my favorite by far is the video below, which a colleague brought to my attention via a very detailed description of octopus reproduction written by Julie Kalupa of University of Wisconsin - La Crosse. This wonderful video by Lurynn Evans shows a female Giant Pacific Octopus in Puget Sound caring for her ~ 50,000 eggs and their subsequent hatch. Enjoy!