Does the parasite give specific behavioral instructions? If the shrimp eats the neural matter are they susceptible to kuru (would that be mad shrimp disease)? If they've already been hijacked, would we even be able to observe and separate parasitic generated behaviors and prion disease-type behaviors? Shrimp technically can be affected by prions, but are they?
And just how much cannibalism is parasite driven?
More research required!