The animal devoid of pleural space is______________.

Elephant is the only animal known to have no pleural space. Rather, its parietal and visceral pleura are both composed of dense connective tissue and joined to each other via loose connective tissue. This lack of a pleural space, along with an unusually thick diaphragm, is thought to be an evolutionary adaptation allowing the elephant to remain underwater for long periods of time while breathing through its trunk which emerges as a snorkel.