Zooxanthellae

Physiology

Physical characteristics
- Zooxanthellae are part of the group dinophyta, which are single-celled mixotrophic microorganisms.

This class of organisms has two flagella, one transverse and one longitudinal. The longitudinal flagella is used as a rutter for directional steering.

The transverse flagella is used for propultion. It is two to three times the length of the longitudinal flagellum and is composed of axoneme, which causes the

organelle to take on a striated form (like a ribbon). The flagella possess mastigonemes (small flagellar hairs).

Dinoflagellates use thecal plates as a method of defense against predators. Theca are armor-like plates on the exterior of the cell that are composed

of cellulose. Note: individuals may not have thecal plates at all stages of their life cycle.

Genetic characteristic
- part of a group of dinoflagellates
  - Flagellated
  - Thecal Plates
Zooxanthellae is the name given to a wide array of different algae of the genus Symbiodinium

Behavior
- live in the tissues of other organisms
  - Cnidarians (Coral Polyps, Jellyfish)

- - Nudibranchs (Sea Slugs)

- Under-represented in the water column

Mutualistic Relationship with Coral Reefs

Photosynthesis
- Corals provide a safe environment and compounds needed for photosynthesis

Zooxanthellae provide food (nutrients) for the coral to use in order to secrete calcium carbonate skeleton
Highly efficient exchange of nutrients
Relationship has lasted for more than 200 million years
- Sugar/Carbohydrate Export
- Amino Acid Export