In honor of Darwin Day, I’d like to give a little shout out to some of Charles Darwin’s contributions to marine science.
Theory of Coral Reef Formation: Onboard the Beagle, Darwin composed the theory of coral reef formation. He described three types of reefs: fringe, barrier, and atoll. His illustrations of reef formation and global reef locations are beautifully detailed. Most impressive is that Darwin came up with the theory without ever having seen a coral reef (though he would eventually see one during the Beagle’s voyage through the Pacific). And remember, back then there were no aerial photographs of atolls, etc. But Darwin’s theory of coral reef formation wasn’t found to be correct until 1951, when U.S. government geologists surveying Eniwetok, a Marshall Islands atoll, prior to a hydrogen bomb test there, finally drilled deep enough to resolve the mystery. Scientists immediately erected a small sign next to the borehole which read “Darwin was right”. Read more about the debate here.
One marine-related hypotheses Darwin had onboard the Beagle: Darwin posited bioluminescence in the sea was the same type of bacteria as that on rotten meat (he was wrong).
Darwin’s Fishes: Daniel Pauly’s book Darwin’s Fishes is an encylopedia of everything Charles Darwin ever wrote about fish, which represented about 0.7% of Darwin’s lifetime ouput. Using fish, Darwin gave the first rigorous account of the importance of colors in biology and also accounts of sexual selection. Pauly also believes that Darwin to be able to deomonstrate the roles isolated islands play in generating biodiversity (and endemism) using fishes.
Barnacles: Back from the Beagle but still sitting on his theory of natural selection, Darwin began a study of barnacles that lasted eight years (photo of Darwin’s barnacle slides). He was first to identify and coin the term “dwarf males” (paired with a female barnacle lacking all male organs) and “complemental males” (housed within a hermaphrodite barnacle). His taxonomy of barnacles is still in use today. Lots of barnacles are named after Darwin and so are some fish, including this one:

Semicossyphus darwini (Galapagos sheephead); drawing by Godfrey Merlen