How does photosynthesis work underwater?

How does photosynthesis work underwater?

fundamentally photosynthesis actually began in the oceans — in underwater, because that’s where plants and algae first evolved. They then moved onto land. So light definitely gets into the upper layers of the ocean and that’s where the process of photosynthesis traps that light and converts it into energy — into carbohydrates really, that the rest of the food chain relies on. So it’s really the idea is that you have to maintain plant life, algae has to maintain itself in the upper layers of the ocean because once you get further down into the depths of the ocean, first of all red light gets absorbed which is why the oceans look blue and green-y colours. Light does get down there but it has to maintain itself up in the high levels. So if you look, for example, at coral reefs and they have plants living inside their tissues or algae and those types of coral have to maintain themselves by growing on big reefs, depositing calcium carbonate in great big layers that build up and build up and as sea levels rise, they have to keep up their pace to keep themselves in that lovely, sunny, gorgeous bit of tropical oceans where we all love to go snorkelling and diving. But as you go deeper down, they tend to peter out, and there are some types of corals actually that don’t have photosynthetic algae in their tissues; they actually rely on catching their food like other animals. They catch it from the water, and those are the ones that live deeper down. So you do see this zonation. You see similar things on the beach with different types of seaweed using different types of pigments to harness light both in the open areas where there’s lots of light and then lower down where light start to get absorbed.