Marine mammals developed numerous anatomical and physiological features to survive in the water. Land legs became flippers or disappeared altogether. Whales and manatees developed flukes, while seals used flippers for steering and propulsion. Lungs became more efficient and the ability to survive long dives arose through adaptations to the circulatory system. A thick layer of fat, the so-called blubber, protects against the cold. The senses of hearing and sight were adapted to the aquatic environment, for example through the ability to conduct sound efficiently in water.
The return to the water enabled marine mammals to occupy new ecological niches, from coastal regions to the depths of the oceans. Today, whales, seals and manatees display a fascinating diversity that reflects their evolutionary journey.
By Fatima Kutzschbach