What do you call a group of musical whales?

This joke swims in the delightful waters of wordplay, specifically a pun. The humor comes from the clever substitution of "orca" – a type of whale known for its distinctive black and white markings – into the word "orchestra." An orchestra, of course, is a large ensemble of musicians playing various instruments, and the sound of it is usually quite harmonious. The twist here is imagining these majestic marine mammals forming their own band, leading to a wonderfully silly image.

Orcas, also known as killer whales, are actually the largest members of the oceanic dolphin family, not true whales, though they are often referred to as such. They are highly intelligent and social creatures, communicating through a complex array of clicks, whistles, and pulsed calls, which some might even describe as their own form of underwater music. The idea of them coming together to perform a symphony, therefore, isn't entirely out of tune with their natural vocal talents, even if it's purely for comedic effect. The joke works by taking a familiar concept, an orchestra, and giving it an unexpected, marine-mammal twist, creating a chuckle-worthy auditory image.