Animals

 Animals belong to the Kingdom Animalia and can be defined in a simplified way as eukaryotic, multicellular, heterotrophic organisms. It is believed, based on the study of fossils, that these organisms arose about 710 million years ago. Many species appeared and many became extinct. As an example of animals that are currently on the planet are: dogs, cats, butterflies, lions, jellyfishes and humans.

As examples of those that became extinct, we can cite the dinosaurs, mammoths and sabre-toothed tiger and others.

There are invertebrate animals and vertebrate animals. Animals that don't have a vertebral column are called invertebrates. These animals present a great number of shapes, colors, and sizes, and some species are known to be microscopic and some are more than 10 meters long. vertebrate animals are those that have a vertebral column. Vertebrate animals are grouped in the phylum called Chordata (cordates). They are often divided into five groups: Fish, mammals, amphibians, reptiles and birds.

There are carnivorous animals, which are those that feed on other animals. There are the herbivorous animals that feed on vegetables or algae. And the omnivorous animals are those that feed on animals as well as on vegetables and algae.

Animals that thrive partly on land and partly in water are called amphibians. Frogs and salamanders are examples of amphibians. The first vertebrates to live fully on earth were reptiles, such as snakes, lizards, and crocodiles. Reptiles have dry, scaly skin. Vertebrates that feed their young with their mother's milk are called mammals. Examples include mice, moose, seals, whales, monkeys. Vertebrates that have wings and feathers are called birds. Almost all birds are capable of flight.

Fishes are the oldest vertebrates known to man. They live in water and are usually covered with scales.

Written by Samara Lopes