Coral reef

[GroovyLady]

How do coral reefs form?

[naz_nomad]

They are mostly Calcium Carbonate ... the skeletons of alga, and other sea critters

[steviep165]

alga? skeletons? since when did soggy green weed have skeletons.

if you're a beginner, try this...

http://esvc000766.wic015u.server-web.com/bb_si te_intro/stage2_Modules/zoo/coral_reef.htm

studied them for a while, do yourself a favour and go dive on them.

[drestie]

Corals are not soggy green weeds. They are colonial hydrozoan cnidarians. They do indeed have bodies made of calcium, and when they die, other coral polyps grow on top of the calcium skeletons left behind, thus forming a reef.
Most corals also have associated algae, which provide the coral hydrozoans with photosynthate as food.

[drestie]

Sorry, stevie. Just reread your post. Yes, you are 100% correct that algae don't have skeletons :)
My apologies, it's been a long night!

[drestie]

And they're Anthozoans, not hydrozoans, of course.
I think it's bedtime for estie!

[brachiopod]

Would that be calcium carbonate in the form of calcite or aragonite, then?