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Ecology and grouping organisms


The animal kingdom can be divided into two major phyla. Animals without backbones are invertebrates, such as spiders and insects. Animals with backbones are vertebrates. The vertebrates can be further divided into classes, such as mammals and birds.

Vertebrate classes

Vertebrate classes and some of their key features

amphibiansmoist permeable skinfrog, newt, salamander
fishgills, wet scalesgoldfish, shark, cod
reptilesdry scalescrocodile, lizard, snake
birdsfeathers,beaksbudgerigar, sparrow, ostrich
mammalsfur, produce, milkrabbit, kangaroo, human, dolphin

Higher only

Some fossil vertebrates and newly discovered species can be difficult to classify. For example, Archaeopteryx is an extinct vertebrate known only by its fossil remains. It has characteristics of birds and reptiles.

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