Lungfish

Lungfish are "living fossils" that bridge the gap between aquatic and terrestrial life, having remained largely unchanged for over 400 million years. These freshwater vertebrates are best known for their dual respiratory systems—using gills to breathe in water and primitive lungs to gulp air from the surface. Because they share a common ancestor with tetrapods (four-legged animals), they are considered the closest living relatives to humans and other land-dwelling vertebrates. Remarkable Survival Tactics

The most striking feature of some lungfish species is their ability to survive extreme drought through a process called . Antimicrobial defenses in the African lungfish - PMC - NIH lungfish