pool of clear water. A few climb into the low branches of mangrove trees. Nearby, a giant honeybee buzzes from flower to flower. Birds paddle through the calm water. None of these animals notice the water


A


monitor on a nearby bank. It silently slips into the water. T is large lizard is looking for prey. It isn’t picky. It will eat birds, fish, frogs, crabs, and snakes. Suddenly, some monkeys spot the lizard.


T ey call out a warning. T en they scramble to higher ground. T e birds flap their wings. Water sprays as they take flight. T e lizard turns its tail and swims away—


hungry. It won’t go hungry for long, though. T ere’s lots of prey in this wetland in India. In fact, if the water monitor doesn’t watch out, it may become the prey! A hungry tiger is on the prowl in this wetland, too.


What’s a Wetland? Wetlands exist throughout the world except in Antarctica. Not all are like the one in India. Yet they all have one thing in common. Water covers them for at least part of the year. T is water can come from many sources.


Flooding rivers, melting snow, and rain turn land soggy. Groundwater seeps to the surface and makes land boggy. At high tide, seawater flows inland. In some wetlands, fresh water and salt water mix. T ese wetlands have been around for a long


time. Many formed at the end of the last ice age. Back then, giant rivers of ice flowed across the land. T ey dug into the ground. T en these low-lying places slowly filled with soil, other debris, and water. Water-tolerant plants grew. Animals moved in.


18 NATIONAL GEOGRAPHIC EXTREME EXPLORER


group of monkeys gathers by a


Why Wetlands Matter Over time, wetlands have become some of the world’s most biodiverse ecosystems. Many diff erent kinds of plants and animals live in wetlands. T at’s because they’re part land and part water. So both land and water organisms can survive in them. Wetlands don’t just help plants and animals,


though. T ey help people and the planet. For example, wetlands clean polluted water. T is pollution can come from many places.


Factories dump chemicals into rivers. Fertilizer and pesticides seep into groundwater. Rain washes animal waste into waterways. Too much pollution can poison drinking


water. It can harm people, plants, and animals. Wetlands filter the polluted water. As it


flows into a wetland, this dirty water soaks into the soil. T e soil traps it. T en bacteria and other tiny organisms slowly break down the pollution. T ey make it less harmful. T ey clean the water. Wetlands have a lot in common. Yet not


all wetlands are the same. To see how they’re diff erent, take a look at the three main kinds of wetlands. It’s time to visit a swamp, a marsh, and a bog.


This giant river otter fi nds plenty of fresh food in its wetland habitat.


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