Barnacles are known for having very long penises. National Geographic reported in 2008:
To cope with changing tides and a sedentary lifestyle, the gnarly crustaceans have evolved penises that are eight times the length of their bodies—the longest relative to body size of any animal.
My sedentary lifestyle has had no such effect. I feel cheated.
That article also noted that barnacles have the ability to change the size and shape of their penises to suit their living conditions.
Barnacles living in gentle waters have long, thin penises best equipped for maximum reach, the study found.
But those animals living in rough waters have shorter, stouter penises that are better able to withstand strong waves. […]
The researchers also transplanted barnacles living in gentle waters to rough waters and vice versa, to make sure the penis variations they observed were a result of the environment and not due to genetic differences.
The results showed that barnacles could indeed change the width and length of their penises to suit the wave conditions of their new homes.
There should be an X-Men character with this power. Much more useful than wings or prehensile toes.
A new study exposes a shocking barnacle sexual practice: spermcasting.
The Pacific gooseneck barnacle is the first species of ocean-dwelling arthropods — the group that includes crustaceans, insects, and spiders — known to spermcast.
Just as it sounds, spermcasting occurs when a male barnacle sends out his sperm into the water, and females pick it up and fertilize their eggs. Other species such as sponges, jellyfish, and sea anenomes are known to spermcast. […]
How the females get fertilized by spermy water is still unknown.
Barnacles cast sticky sperm masses into the water fairly regularly, so a “scenario that might happen is as the tide comes in and waves start to break over the top of [the male barnacles], clumps of sperm are picked up, and downshore individuals … could capture it,” [evolutionary biologist Richard] Palmer said.
I will never, ever swim in the ocean again. Eeww.