Algae absorb sunlight by photosynthesis and convert solar energy into chemical energy which they use in growth or to store within the cell. Algae are the primary producers within this marine ecosystem.
Unlike land plants which obtain their nutrients from the soil by absorption through roots, algae absorb the nutrients they require directly from the seawater that surrounds and supports their fronds. Algae do not have absorption roots, their holdfast only holds them down onto a firm surface.
The large algae that we see on a shore are called macroalgae, and unusually there are surprisingly few shore animals that live entirely by eating algae fronds.
The other algae group is the microalgae, consisting of single-celled plants, spores, and minute juvenile plants which occur in their millions suspended in the water as plankton or coating the rocks as part of the deposited slime, or gaining a foothold to grow into a larger plant.
Large algae plants produce thousands of cells in each frond and on the frond surface. Under the constant swashing of the waves, these cells erode away from the plant. These cells become suspended in the water and are subjected to bacterial action. Others are filtered and consumed by other animals.
Some examples of green algae are:
Sea lettuce, Ulva lactuca
Green Sea Velvet, Codium fragile
Caulerpa, Caulerpa filiformis
Some examples of brown algae are:
Neptune's Necklace, Hormosira banksii
Leather Kelp, Eklonia radiata
Strap Weed, Phyllospora comosa
Some examples of red algae are:
Coralline Seaweed, Corallina officinalis
Encrusting Corallines, Corallinaceae species.
Clayton, M.N. & King, R.J. (1981). Marine Botany: an Australian perspective. Longman Cheshire.
Cremona, J. (1988). A Field Atlas of the Seashore. p. 32, Cambridge University Press, Cambridge.
Pope, E.C. & McDonald, P.M. (1981). Exploring Between Tidemarks. p.27, The Australian Museum.