![]() ![]() ![]() They do, however, still breathe air, having never developed anything equivalent to the gills of their earlier marine incarnation. Whales (including the small whales we call dolphins) and dugongs, with their close cousins the manatees, ceased to be land creatures altogether and reverted to the full marine habits of They show us what the intermediates might have been like, on the way to extreme cases such as whales and dugongs. Moving from water to land involved a major redesign of every aspect of life, including breathing and reproduction. Nevertheless, a good number of thoroughgoing land animals later turned around, abandoned their hard-earned terrestrial re-tooling, and returned to the water again. And we mustn’t forget the plants, without whose prior invasion of the land none of the other migrations could have happened. ![]() In addition to the reptiles, birds, mammals and insects which we see all around us, other groups that have succeeded out of water include scorpions, snails, crustaceans such as woodlice and land crabs, millipedes and centipedes, spiders and various worms. At various points in evolutionary history, enterprising individuals within many different animal groups moved out onto the land, sometimes even to the most parched deserts, taking their own private seawater with them in blood and cellular fluids. If you go back far enough, everything lived in the sea. ![]()
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