Symbioses
 

Explanations for answers to quiz on the origin of nutrients required by symbiotic zooxanthellae in corals:

 
   

From seawater, including that contained within the host's gut cavity. Yes. Even though waters around coral reefs are notably deficient in nutrients, at least some nitrates, phosphates, and micro-nutrients such as iron could be obtained from this seawater source.

diagram showing answer 1 to quiz on nutrient origin for symbiotic zooxanthellae in coral polyps

From the host's tissues. Yes. Of principal importance would be carbon dioxide and ammonium (NH4 +), the latter representing a source of nitrogen. Both substances are released as waste products from the host's metabolism and both are required for photosynthesis.

diagram showing answer 1 to quiz on nutrient origin for symbiotic zooxanthellae in coral polyps

From digestion of food particles within vacuoles within the gastrodermal cells. Yes. The close proximity of the digestive vacuoles to the zooxanthellae would mean that nutrients from digestion of prey are likely available for the photosynthetic processes of the zooxanthellae.

diagram showing answer 1 to quiz on nutrient origin for symbiotic zooxanthellae in coral polyps

From the host's digestive wastes. Yes. This is possible. Soluble nutrients leachiing from undigested food residues, if usable for photosynthesis, could be taken up by the gastrodermal cells and made available to the zooxanthellae in their vacuoles.

diagram showing answer 1 to quiz on nutrient origin for symbiotic zooxanthellae in coral polyps
 
  RETURN TO MUTUALISM