It is not entirely clear why some cats have a strong reaction to cucumbers, but it is believed to be related to their innate predatory instincts. Cats are naturally cautious animals and are easily startled by sudden movements or unfamiliar objects. Cucumbers, being long and green, have a resemblance to a snake, and when placed behind a cat, it can startle them and trigger a fear response. This reaction may also be due to the fact that cucumbers are not a familiar object for cats, as they do not naturally occur in their environment.
It is worth noting that scaring animals for entertainment is not recommended, and It’s important to remember that even if it may be amusing to see a cat’s reaction, it’s not a kind way to treat an animal.