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Digestive System – Biology and Evolution

By |2019-05-07T20:07:23-07:00May 26th, 2017|Biology|

Digestive system: A hydra eating: the mouth is where all the tentacles come together,near the center of the picture.The hydra is eating the round bug in its stomach. Before digestive systems... Starting about 3.8 billion years ago, during the Archaean Era, one-celled creatures were the earliest living things. They just floated in the ocean [...]

Circulatory System – Biology and Evolution

By |2019-04-06T18:43:26-07:00May 26th, 2017|Biology|

Circulatory system: A dog heart What is the circulatory system? The circulatory system takes food and air from outside your body and brings it all over your body so that all your cells get the food and oxygen they need to stay alive. The first cells evolve The nervous system The digestive system [...]

Evolution of Frogs – Biology

By |2019-06-26T22:18:04-07:00May 26th, 2017|Biology|

A frog sitting half in the water: Evolution of frogs When did frogs evolve? Frogs developed out of lungfish about 375 million years ago, in the Devonian period. They used their lungs to leave the water and live on land. Read more about lungfish All our biology articles In the Devonian period, it was [...]

Lungfish – Evolution of Fish

By |2018-04-15T17:26:06-07:00May 26th, 2017|Biology|

Evolution of fish: a lungfish About 400 million years ago, during the Devonian period, the Earth was going through an especially warm period. Some of the smaller oceans and lakes were drying up, leaving big muddy puddles all around them. This was no good for fish, which had less room to swim around [...]

History of Fish – Biology

By |2019-06-09T19:14:03-07:00May 26th, 2017|Biology|

History of fish: it looks like a severed tentacle but it's a lamprey. When did fish evolve? About 510 million years ago, in the Cambrian period, some of the worms on Earth evolved into the earliest fish. Segmented worms The Cambrian Period All our biology articles How were fish different from worms? Fish [...]

What are arthropods? Biology

By |2019-02-03T21:35:07-07:00May 25th, 2017|Biology|

Bee on a flower What are arthropods? Insects, spiders, crabs, and lobsters are all arthropods, so there are a lot of arthropods on Earth. Annelid worms All our biology articles When were the first arthropods? The earliest arthropods on Earth developed about 550 million years ago. That was during the Proterozoic period. Proterozoic [...]

Evolution of Grasshoppers – Biology

By |2019-07-15T10:07:25-07:00May 25th, 2017|Biology|

Evolution of grasshoppers: Grasshopper sitting on a leaf Why do grasshoppers jump? When grasshoppers first evolved from earlier insects, about 300 million years ago, they lived in forests of huge ferns, and the main danger to grasshoppers came from frogs. Like frogs, grasshoppers evolved to be good jumpers.They ate mainly ferns. What are [...]