bio

Zooxanthellae

A functional nickname for the single-celled photosynthetic algae that live inside the cells of corals and many other marine animals — mostly dinoflagellates of the family Symbiodiniaceae. It is not a taxonomic group but a *role*: the animal gives the algae a lit, sheltered home plus nitrogen- and phosphorus-rich metabolic waste; in return the algae hand over as much as 90–95% of the carbon they fix by photosynthesis, as sugars and amino acids. This partnership feeds the coral reef in nutrient-poor tropical water — and is fragile enough that a few degrees of warming can break it.