Every living thing on Earth requires water to survive. Aquatic ecosystems including lakes, rivers, oceans, estuaries and wetlands are all key to survival for many animals. Explore the animals living in the Okavango river delta, the deep sea and Lake Tanganyika this March with National Geographic. Catch World of Water, Saturdays at 6pm this March, on National Geographic WILD UK. | National Geographic UK

Freshwater makes up just 3 percent of all the water on Earth, yet it supports countless species—from the manatees in Florida's fragile waterways—to humans. "We all have to pitch in." | National Geographic