Whales: From Land-Dwelling Ungulates to Giants of the Seas

This lecture, held on June 21, 2023, as part of the lecture series "Eine Uni -Ein Buch: 'The Whale Rider'.Eine Erkundung Neuseelands mit Witi Ihimaeras Roman", is about whales (Cetacea), which are an order of aquatic mammals that have secondarily shifted their habitat from the mainland back into the sea.In the Paleogene period, more precisely in the Eocene epoch, over 50 million years ago, the evolution of whales began from small, land-living ungulates about the size of a larger dog to today's giants of the seas weighing up to 200 tons.This development took place on the coasts of the Tethys Ocean, which at that time still lay between India and Asia, and is clearly supported by both morphological and genetic evidence.The land-sea transition is excellently documented by fossils from the Paleogene sedimentary deposits that are now exposed in the Indo-Pakistan region.Herein I will explain this evolution of whales and the complex morphological (reduction and transformation of limbs to fins, changes in bone structure) and physiological adaptations (inner ear modification for underwater hearing, modified lung breathing with blowhole, insulating fat layer and cardiovascular blood circulation system to minimise heat loss) that were necessary for this fundamental habitat change.I will also discuss how the evolution of whales is closely linked to plate tectonic, climatic and oceanographic changes through time.The first archaic whales still had fur and four limbs, and although they had a semiaquatic lifestyle, they were still able to walk on land.Modern whales evolved from these archaic whales, first the toothed whales and then the plankton-eating baleen whales, which produced the largest animals that have ever lived on our planet.