Disappearing frogs - Kerry M. Kriger

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Frogs (and amphibians in general) are in danger -- worldwide, nearly one-third of the world's amphibian species are on the verge of extinction. And yet, frogs contribute to our well-being in many important ways. Kerry M. Kriger describes why frogs are in trouble and how you can help save them.

Lesson by Kerry M. Kriger, animation by Simon Ampel.

Have you ever heard the sound of frogs

calling at night?

For hundreds of millions of years,

this croaking lullaby has filled the nighttime air.

But recent studies suggest

that these frogs are in danger

of playing their final note.

Over the past few decades,

amphibian populations have been rapidly disappearing worldwide.

Nearly one-third of the world's amphibian species

are endanger of extinction,

and over 100 species have already disappeared.

But don't worry, there's still hope.

Before we get into how to save the frogs,

let's start by taking a look

at why they're disappearing

and why it's important to keep them around.

Habitat destruction is the number one problem

for frog populations around the world.

There are seven billion humans on the planet,

and we compete with frogs for habitat.

We build cities, suburbs, and farms

on top of frog habitat

and chop forests

and drain the wetlands

that serve as home

for numerous amphibian populations.

Climate change alters precipitation levels,

drying up ponds, streams, and cloud forests.

As the Earth's human population continues to grow,

so will the threats amphibians face.

There are a variety of other factors

contributing to the frogs' decline.

Over-harvesting for the pet and food trade

results in millions of frogs

being taken out of the wild each year.

Invasive species,

such as non-native trout and crawfish,

eat native frogs.

Humans are facilitating the spread

of infectious diseases

by shipping over 100 million amphibians

around the world each year,

for use as food, pets, bait,

and in laboratories and zoos

with few regulations or quarantines.

One of these diseases,

chytridiomycosis,

has driven stream-dwelling amphibian populations

to extinction

in Africa,

Australia,

Europe,

and North, Central, and South America.

On top of all these problems,

we add hundreds of millions of kilograms of pesticides

to our ecosystems each year.

And these chemicals are easily absorbed

through amphibians' permeable skin,

causing amino suppression,

or a weakened immune system

and developmental deformities.

Okay, so why are these little green guys

worth keeping around?

Frogs are important for a multitude of reasons.

They're an integral part of the food web,

eating flies, ticks, mosquitoes,

and other disease vectors,

thus, protecting us against malaria,

dengue fever,

and other illnesses.

Tadpoles keep waterways clean

by feeding on algea,

reducing the demand

on our community's filtration systems

and keeping our cost of water low.

Frogs serve as a source of food

for birds, fish, snakes, dragonflies, and even monkies.

When frogs disappear,

the food web is disturbed,

and other animals can disappear as well.

Amphibians are also extremely important

in human medicine.

Over ten percent of the Nobel prizes

in physiology and medicine

have gone to researchers

whose work depended on amphibians.