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Nutrient Absorbers

Photo of kelps along southern Australian shoresAlgae 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.

Algae are grouped into three major groups. These are the Phylum Chlorophyta or Green Algae, the Phylum Phaeophyta the Brown Algae and Phylum Rhodophyta, the Red Algae.

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:

Small photo of Sea LettuceSea lettuce, Ulva lactuca



Small photo of Green Sea VelvetGreen Sea Velvet, Codium fragile



Small photo of Calerpa algaeCaulerpa, Caulerpa filiformis



Some examples of brown algae are:

Small photo of Neptune's NecklaceNeptune's Necklace, Hormosira banksii



Small photo of Leather KelpLeather Kelp, Eklonia radiata



Small photo of Strap WeedStrap Weed, Phyllospora comosa



Some examples of red algae are:


Small photo of Coralline SeaweedCoralline Seaweed, Corallina officinalis



Small photo of Encrusting CorallinesEncrusting 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.

Feeding Relationships

Nutrient Absorbers
Grazers & Browsers
Suspension Feeders
Deposit Feeders
Trophic Levels
Energy Pyramid

Home Page
Rocky Shores
Tidal Levels
Intertidal Zonation
Environmental Factors
Biological Factors
Feeding Relationships


photo of Keith DaveyLife on Australian Seashores
by Keith Davey (C) 2000

Learning Consultant - Media
The University of Newcastle

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Scientific Consultant: Phil Colman
site created 01.01.98 : updated 01.04.2000