1001 Space Earth Earth Rocks and Minerals Landscape Sea Weather and Climate Natural Disasters Resources Nature History Human World Science and Technology

Choose a Page:*How long has there been life in th...*How much of the Earth is covered b...Why does seawater taste salty?Is the ocean floor flat?What causes waves?What is an iceberg?Are tidal waves caused by the tides?What are ocean currents?How has the ocean bed been measured?How does the sea affect the climate?How do coral reefs form?Are there currents at great depths?Why does the tide come in and go out? How long has there been life in the sea? The sea is where the Earth's first living creatures evolved. The earliest clear fossils date from 570 million years ago. Before then, animals had no hard parts and so did not fossilise. Some 175 million years later, fish were well-established in the sea and were spreading to rivers and lakes. Some 195 million years ago, squid-like creatures with shells were common. Giant squid up to 66 ft. (20 m) long survive today in the ocean depths. Two giants of the ocean depth are the giant squid and the sperm whale, which can be more than 18 metres long.   Previous: Back Book: 1001 Section: Earth Chapter: Sea