As a marine biologist I am always spellbound watching whales on the open sea. Witnessing their majestic movements, they are the most marine of all creatures, but I never fully appreciated their origins until I researched the topic before writing SOT. I focused on the ancestors of cetaceans because they are super-cool and are a great hook to get people to read my book. They also use sonar and sing songs and thus are perfect to play a major part of the “songs” of Thalassa (but they are not the only ones).