Core Curriculum

Biology Lessons

Secondary


 
Ecology
The Life of a Cell
Genetics
Change Through Time
Viruses, Bacteria, Protists, and Fungi
Plants
Invertebrates
Vertebrates
Fish, Amphibians, and Reptiles...Five hundred million years ago, the Earth experienced a dramatic increase in the diversity of life. This Cambrian Explosion resulted in the creation of most of the phyla still in existence today, including primitive vertebrates. True vertebrates such as fish and sharks evolved 480 million years ago (mya) during the Ordovician Period. The first land vertebrates arrived during the Devonian Period 420 mya. Ancestors of modern fish, amphibians, and reptiles hold clues to how animals may have adapted from life in the water to life on land. Amphibians are creatures that, like fish, require wet environments, breathing through their skin. Unlike fish, however, amphibians have arms and legs, allowing them to move through shallow waters onto land. Reptiles have adapted to life entirely on land, having dry protective skin and amniotic eggs. Reptiles populated the land, avoiding predators at sea. Further adaptation resulted in the evolution of dinosaurs, reptile in appearance yet possessing bird-like features. The domination of the dinosaurs during the Mesozoic Era (248-65 mya) ended with sudden mass extinction, followed by the dominance of birds and mammals. The Earth is home to a vast diversity of modern fish, amphibians, and reptiles. Unfortunately, human pollution and land-use change is causing devastating destruction of ecosystems, threatening the extinction of many of these species. Indeed, the suggestion that we are in the midst of a Sixth Mass Extinction warns humanity of the critical necessity to preserve animal diversity.
The Human Body
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