Friday, 11 February 2011

First Life on Earth

The first living thing was neither an animal nor a plant
The oldest fossils found by scientists date back about 3 billion years. They take the form of round, cushion-shaped deposits of limestone. These are the remains of colonies of thousands of tiny living things called blue-green algae. These algae contain just a single cell and are neither animal nor plant.

The first animals were as soft as jelly
Animals do not produce their own food, but gain nourishment by eating living things such as plants or other animals. The first animals were single-celled creatures that ate single-celled pants. Later animals were made up of hundreds of cells but were all soft and lacking any hard parts. Charnia grew attached to the seabed, while jellyfish floated freely.

Plants appeared around 1000 million years ago
These early plants were green algae. These single-celled plants had chlorophyll, the green substance that enables plants to convert sunlight to energy. These algae produced oxygen, gradually making the Earth’s atmosphere able to sustain more advanced forms of plant and animal life.

Early land plants simply clung to rocks
By about 800 million years ago, some algae was growing together with fungi to form lichen. Lichen is able to grow on bare rock, creeping across the surface as it grows. The chemicals produced by lichens help break rocks down into grit and soil.

Plants that can stand up are called vascular plants
Gradually, more complex plants evolved. These had more than one cell. Vascular plants have several different sorts of cell. Some form vascules which transport water and food from one part of the plant to another. When these vascules form stems, a plant can stand upright. One of the earliest such plants was Cooksonia.

Anomalocaris hunted other animals
The creatures Anomalocaris lived about 520 million years ago in what is now Canada. It used its fins to swim through the shallow seas in search of prey. Smaller animals were caught in its two pincers, then pushed into its mouth. Anomalocaris grew to be about 60cm long.

I Don’t Believe It!
None of the early animals had bones. They were made up almost completely of muscle, skin and other soft tissue.

No comments:

Post a Comment