17.1: Modern Biodiversity

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Do you know life on Earth?

It's likely that there are many places on Earth that you would not recognize as being on your home planet. There are also many creatures that you would not realize that you share a planet with. That's because of the incredible diversity of species. Wouldn't it be fun to see some of these unusual creatures?

Biological Diversity

More than 1.3 million species of organisms have been cataloged. Many millions of species have not been discovered yet. Scientists estimate that there may be about 8.7 million species in all. Why does the planet have so much biological diversity? (Biological diversity is shortened to biodiversity.) The tremendous variety of organisms is due to the tremendous numbers of habitats that they have evolved to fill.

Ways to Live in the Environment

Each organism has the ability to survive in a specific environment. Dry desert environments are difficult to live in. Desert plants have special stems and leaves to conserve water (Figure below). Animals have other ways to live in the desert. The Namib Desert receives only 1.5 inches of rainfall each year. The Namib Desert beetle lives there. How do the beetles get enough water to survive? Early morning fog deposits water droplets. The droplets collect on a beetle's wings and back (Figure below). The beetle tilts its rear end up. When the droplet is heavy enough, it slides forward. It lands in the beetle’s mouth. There are many other environments that need unique approaches for survival (Figure below and below).

Aloe vera plants have fat, waxy leaves that allow them to conserve water

Aloe vera plants like these ones have fat, waxy leaves that allow them to conserve water.

The Namib Desert Beetle has bumps on its back for collecting water

The Namib Desert Beetle has bumps on its back for collecting water.

Stoats change color in the winter, from brown to white, so that they can hide in the snow

Stoats change color in the winter, from brown to white, so that they can hide in the snow.

Crowned cranes have plumage that helps them attract a mate

Crowned cranes have plumage that helps them attract a mate.

Getting Food and Being Food (Or Not)

Organisms must be able to get food and avoid being food. Hummingbirds have long, thin beaks that help them drink nectar from flowers. Some flowers are tubular. Different species of flowers have tubes of different lengths. Different species of hummingbirds have different lengths of beaks. A particular hummingbird species has evolved to feed from one or a few species of flowers.

The battle between needing food and being food plays out in the drama between lions and zebras. When a herd of zebras senses a lion, the animals run away. The zebras’ dark stripes confuse the lions. It becomes hard for them to focus on just one zebra. The zebras may get away. But lions are swift and agile. A lion may be able to get a zebra, maybe one that's old or sick.

Summary

There are 1.3 million known species, but many more have not been discovered.
The enormous number of species is due to the tremendous variety of environments in which they can live.
Organisms have features that help them to find food or avoid being eaten.

Review

Study the organisms in the photos above. For the aloe vera plant and the beetles, list the features that each has for successful living.
Study the organisms in the photos above. For the stoats and the crowned crane, list the features that each has for successful living.
How does being well suited for a particular environment lead to biodiversity?

Explore More

Use the resource below to answer the questions that follow.

What is biodiversity?
How did so much biodiversity come about?
How does biodiversity help people?
Why is biodiversity important?
Why are so many species disappearing now?
How many species are disappearing from tropical rainforests each year? Why?