After graduating, he joined the United States Army and was stationed in Honolulu, Hawaii where he spent his free time surfing and swimming in the Pacific Ocean.
[9][8] Ellis spent most of his life traveling to exotic locations and used scuba gear and a steel cage to swim with various marine animals.
[9] His photorealistic paintings of whales were published in Audubon, National Wildlife Magazine and Encyclopedia Britannia.
He maintained an affiliation with the American Museum of Natural History for most of his life but is most well-known for writing and illustrating books on marine animals.
His notable works include The Book of Whales (1980), Monsters of the Sea (1994), The Search for the Giant Squid (1998), and Tuna: A Love Story (2008).