Confidence: I'm as sure as I can be.
Notes: In the photo's you can see a mass under the crabs 'tail' this is called the externa and it contains the barnacles reproductive structures. If this was a normal berried crab you would be able to see the definition of each egg. This is a smooth mass. The barnacle can infect male and female crabs. It tricks them in to thinking they are pregnant. The crabs start to behave like berried females, protecting the mass. It prevents the crabs from moutling and effectively castrates the male as he starts to behave like a female. The barnacles have a root like system throughout the crab which they use to absorb nutrients.