Marine life is a vast resource， providing food， medicine， and raw materials， in addition to helping to support recreation and tourism all over the At a fundamental level， marine life helps determine the very nature of our Marine organisms contribute significantly to the oxygen cycle， and are involved in the regulation of the Earth's Shorelines are in part shaped and protected by marine life， and some marine organisms even help create new Marine biology covers a great deal， from the microscopic， including most zooplankton and phytoplankton to the huge cetaceans (whales) which reach up to a reported 48 meters (125 feet) in The habitats studied by marine biology include everything from the tiny layers of surface water in which organisms and abiotic items may be trapped in surface tension between the ocean and atmosphere， to the depths of the oceanic trenches， sometimes 10，000 meters or more beneath the surface of the It studies habitats such as coral reefs， kelp forests， tidepools， muddy， sandy and rocky bottoms， and the open ocean (pelagic) zone， where solid objects are rare and the surface of the water is the only visible A large proportion of all life on Earth exists in the Exactly how large the proportion is unknown， since many ocean species are still to be While the oceans comprise about 71% of the Earth's surface， due to their depth they encompass about 300 times the habitable volume of the terrestrial habitats on EMany species are economically important to humans， including food It is also becoming understood that the well-being of marine organisms and other organisms are linked in very fundamental The human body of knowledge regarding the relationship between life in the sea and important cycles is rapidly growing， with new discoveries being made nearly every These cycles include those of matter (such as the carbon cycle) and of air (such as Earth's respiration， and movement of energy through ecosystems including the ocean) Large areas beneath the ocean surface still remain effectively 注意： 这篇文章里sea life被称为marine life， 其实都是一回事。
Environmental ProtectionNowadays， the issue of environmental protection is becoming more important in We need to be more aware of the dangers of pollutions on earth as well as on our Although we're becoming more technologically advanced， our health is also taking it's This is evident because we see more and more people wearing sunscreen because of the thinning of the ozone Overall， a simple step in protecting our health and the environment is to
