Green Seaweeds

Green seaweeds are found on both sandy and rocky beaches. Many can tolerate low salinity and will colonise areas where rivers meet the sea. The green colour of the seaweed is due to the green pigment chlorophyll required for the photosynthesis of light.

Using only chlorophyll means that green seaweeds require good levels of light and therefore will not thrive in shadowed areas or too any depth. It does give them an advantage, the ability to live higher up shore without competition from the red or brown seaweeds.

       Sea Lettuce Ulva lactuca   

      Velvet Horn Codium tomentosum

       Gut Weed Enteromorpha intestinalis

      Unidentified Green Seaweed

Sea Lettuce Ulva lactuca

This is a green seaweed which looks similar to a lettuce leaf and is edible. The sea lettuce can reach plague levels completely covering beaches.

If wave action detaches them they will float off but not die but instead keep growing and eventually be stranded en mass elsewhere. Any large collection on beaches particularly sheltered fine sandy ones will affect the environment.

Gut Weed  Enteromorpha intestinalis   

A very common seaweed occurring at all levels of the beach. This grass like seaweed is filled with air. It is very tolerant to varying levels of salination, thus enabling to even survive in the rock pools at the highest levels on the beach. Here the pools are uncovered much of the time and suffer from evaporation, severely increasing salinity levels or when they fill with rainwater and levels drop.

In summer when these higher pools dry out, Enteromorpha intestinalis will bleach white. The seaweed even grows where limpets have completely denuded all seaweed (excluding Lithothamnia) in the rock pools, by growing on the limpets shells.

Velvet Horn Codium tomentosum

A dark green seaweed looking similar to deer horns. Their surface appears velvety.

Unidentified Green Seaweed Photographed Marazion

Here is a green seaweed that we have not yet been able to identified.