How does life thrive there without photosynthesis? The diversity of marine life in these systems is surprising.
On land, life is almost completely dependent on photosynthesis. Plants utilize carbon dioxide and sunlight to produce organic matter. But not only the plants themselves benefit; they serve as the bottom of the food chain.
Animals with a plant-based diet gain their energy from eating plants, and they in turn serve as energy source for meat-eating animals on top of the food chain. So, if there is no light, there is no food, and thus no life dependent on photosynthesis. Aside from life on land thriving due to sunlight, what happens in places completely drenched in darkness?
The oceans present a habitat almost entirely governed by darkness. Only the uppermost layer of the ocean is penetrated by sunlight and in the top 200 m photosynthesis is possible:
In shallow, coastal areas, a range of marine organisms are capable of photosynthesis, taking on the role of plants on land. Far from any coastlines, phytoplankton – tiny marine organisms doing photosynthesis – are the only photosynthetic source of organic matter.
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