help with seaweed question

[leifus]

my sisters homework has a question:

how does seaweed retain moisture when washed up on the beach?

research on google went quite far but we got as far as a complex root system called hold-fast

anyway over to you

thanks

[RobSutton]

Most don't they simply die.

The only ones that can survive any length of time exposed are those that live at the top of the sea shore and they have adaptations like thick mucus coatings or structural adaptations to help reduce water loss - Channel Wrack has a "U" shaped cross section which helps traps and keep water inside the dense clumps it grows in, Spiral Wrack twists into a spiral as it dries to help trap water inside the spiral. Their epidermal cells also tend to have thicker cell walls than do seaweeds from lower down the shore.

The holdfast is simply to hold on with they don't take up water, they're not like "normal" plants which have roots that can take up water and a transport system to move it around.

[ceterach]

Hi Leifus

From the bygone days of my education I seem to remember that you should have a look at agar and carageneen and their water retentive properties. The holdfast is just that.

Rob has said it better whilst I was typing!!!!!!!!!!!

All the best

[leifus]

Thanks Rob and Ceterach - thats great - just what we needed

[KeenTeen17]

you know sometime you are going to have to do your own homework rather than WAB.

[leifus]

Originally Posted by KeenTeen17

you know sometime you are going to have to do your own homework rather than WAB.

this was my SISTERS!!