Describe the ecological relationship between the coral and the zooxanthellae algae

firstly they have mutualistic relationship .Coral provides the algae with protected environment and compounds they need for photosynthesis .

infact ... as much as 90% of the organic material photosynthetically produced by zooxanthellae is transferred to the host coral tissue

not sure if this is what you'r looking for eubacteria and archaebacteria