Detective Dannovo: It can't be a shark, John. When this ecosphere was created, they didn't make any sharks.
Detective Dannovo: We scan for biologicals very thoroughly at all ports of entry. You wouldn't be able to get a shark embryo past Customs.
Detective Dannovo: And before you even think it, you can't evolve a shark from our fish stock, in six thousand years, let alone the six hundred years we've had oceans.
Detective Dannovo: The only people dumb enough to get spooked by shark tales are the tourists.
Der Trihs: Right. Because they're the ones getting eaten by the sharks.