Question

Among the red, green and brown algae that inhabit the sea, which is likely to be found in the deepest waters? Why?

Answer 1

Algae is a group of photosynthetic organisms living in aquatic habitat. On the basis of pigments the algae are classified into the following:

• Red algae: Contain phycoerythrin (absorb the blue light), apart from chlorophyll a.
• Brown algae: Contain fucoxanthin (absorbs blue-green to yellow-green part of the visible spectrum (450 to 540 nm)), apart from chlorophyll a.
• Green algae: Contain chlorophyll b (absorbs mostly blue and yellow light), apart from chlorophyll a.

The long wavelengths of the light spectrum—red, yellow, and orange—cannot penetrate deeper into the ocean compared to the short wavelengths of the light spectrum—violet, blue and green.
Among all the colors of the visible spectrum, blue light (high energy, short wavelength) can penetrate the deepest into oceans. Phycoerythrin in red algae can absorb blue light better than the brown and the green algae. Therefore, it can grow better in deeper areas.