There were twenty-odd penguins at this exhibit, and the caretakers claimed that they were all named and could be recognized on sight. I responded to this information with some skepticism, but there are subtle (in some cases, very subtle) differences in how they look. Since they do apparently have to have independent medical records and such, there must be a way to tell them apart; I just wonder what happens if the people who know which ones are which can't come to work. I presume that there must be some additional means of identification.