70% of the Earth’s surface is covered by ocean, and the blue of the ocean stands out when you look at a globe. There are many marine organisms, with 230,000 species living there. The ocean provides us with the salt and fish we need for life, and it’s amazing how the water circulates as water evaporates from the ocean.
https://www.kaijipr.or.jp/mamejiten/shizen/shizen_5.html
I recently learned that the ocean not only provides water, but also a lot of oxygen. Apparently, there is more oxygen supplied from the ocean than from land. I always thought of photosynthesis as something that happens to plants on land, but it seems that 50-85% of the oxygen comes from the photosynthesis of phytoplankton and seaweed in the ocean. Phytoplankton is amazing.
https://scuba-monsters.com/oxygen-sea
Plankton includes microorganisms ranging in size from a few microns to jellyfish over a meter in size, and are “drifting things” that can swim on their own but cannot resist ocean currents and are carried along by them. I thought plankton was just microorganisms.
https://shizen-hatch.net/2022/01/27/plankton
Plankton live at depths of about 100m, and it seems that light cannot reach them deeper than 150-200m, making photosynthesis impossible. So most food chains that feed on plankton take place from the surface to a depth of about 200m. The area up to a depth of about 200m is called the “shallow sea,” and anything deeper than 200m is called the “deep sea.” 95% of the ocean is deep, with some places deeper than the height of Mount Everest, and it is said to be more difficult to reach than space.
https://onlineshop.sunshinecity.jp/blog/post-1607
The deep sea seems to be an unknown territory with much that is still unknown, but here is one recent news discovery. It was thought that oxygen could not be produced in the deep sea because light does not reach there and photosynthesis is not possible, but it seems that oxygen has been confirmed in the deep sea. Oxygen called “dark oxygen” was produced from lumps of iron and manganese oxides and trace metals such as cobalt that had accumulated on the seafloor. The mechanism of oxygen supply from the sea is amazing.
https://www.natureasia.com/ja-jp/research/highlight/14979
I’m sure there will be new discoveries to come, but the ocean and the Earth are amazing, with their vastness, grandeur, and mystery.
