deep in the ocean light can hardly reach, yet there are plants like brown and red algae found here. how do you think they able to synthesis their food?

 Algae live approximately 300 feet under the ocean's surface. They receive oxygen from water and at this depth algae can access sunlight. All algae contain chlorophyll. The pigments of red and brown algae mask the predominant green photosynthetic pigments. Thus prepare food like other plants. Algae receive sunlight and oxygen throughout life and after death only they fall to the bottom of the ocean and decay.