I believe that the author included two anecdotes for the zoo animals, Lucy and Katina, to deepen the meaning of their character. Anecdotes can provide an understanding to their character and creates characterization and even imagery.
I think it’s a sorry if I get wrong
Group discussions can also be categorized based on the topic allotted for the discussion to the participants. There are three kinds of topics-controversial topics, abstract topics and case study topics.
hope this helps ^^