Although Grandad is only a light-hearted series for children, the two "jungle spiders" in this episode are particularly fake, an element of surrealism that the programme doesn't usually go in for.
Grandad and Bert have a conversation about how quiet and subdued his parrot is and how he hasn't squawked all day - during which the parrot squawks three times.
Grandad says that buying exotic trees to care for his parrot will probably cost him his "life savings", despite many previous episodes showing that he doesn't have much money, and can hardly afford to eat.