Why do elephants have big ears?

An elephant's big ears help it to keep cool. Some elephants live in Africa where the sun is very hot. To stay cool their bodies need to be able to lose heat. They lose heat from their blood by passing blood through their large ears. They also cool down by flapping their ears to fan themselves.

Which are the oldest plants?

Plants are divided into lower or higher plants according to their evolutionary history. Algae, diatoms, bacteria, mosses and liverworts are the oldest forms of plant still alive today. They are known from fossils 500 million years old. Conifers appeared about 200 million years ago, and soon afterwards the modem ferns evolved. Flowering plants, known as "angiosperms," first grew about 120 million years ago.