Protists Dinoflagellates (Red tide, Zooxanthellae, Pfisteria) Diatoms Cocolithophores Radiolarians Foraminiferans Algal blooms

Dinoflagellates marine protists, some freshwater mostly unicellular half are photosynthetic- primary producers of aquatic food chains some live in mutualistic relationships with cnidarians, some are parasitic, some are carnivorous two flagella- one transverse (lateral) and one longitudinal (posterior) move in a whirling motion caused by transverse flagellum have a submembrane made of cellulose--makes an “armor”

Red Tide Certain dinoflagellates cause large algal blooms in warm coastal waters (such as along the east coast and in the Gulf of Mexico) turn the water reddish brown because of xanthophylls in the chloroplasts Shellfish eat the blooms and concentrate toxic compounds released by the dinoflagellate cells--toxic to other organisms

Zooxanthellae golden-brown endosymbiont (lives inside) of marine organisms, especially anthozoans (coral) typically dinoflagellate algae, but sometimes diatoms aquired by ingestion reproduce asexually by budding autotrophs gives coral 98% of its energy--in return is given protection, shelter, CO2 for photosynthesis- symbiosis

Pfisteria found in Pamlico and Neuse Rivers in NC complicated life cycle- 24 physical forms, and can change forms quickly most are non-toxic, but some have forms in their life cycles that are toxic two toxins have been identified that can cause skin lesions and are neurotoxins

Diatoms phylum Bacillariophyta eukaryotic algae unicellular, but some form colonies cell wall made of hydrated silica in organic matrix called a frustule marine and freshwater yellow or brown in color asexual or sexual reproduction- sperm only flagellated cells in this phylum

Cocolithophores algae, protists, and phytoplankton in class haptophytes have calcareous (calcium carbonate) shells- called cocoliths index fossils- used to solve stratigraphic problems also nanofossils- indicators of salinity and temp. changes on ocean surface

Radiolarians phylum Actinopoda- “ray feet” marine shells made of silica (glass) after radiolarians die, their shells settle on the sea floor and decompose into a siliceous ooze often contain symbiotic algae like zooxanthellae

Foraminiferans marine-live in sand or attached to rocks and algae- also some families abundant in plankton have porous shells- “Foraminifera” means “to bear little holes” shells are multichambered, made of organic material hardened with CaCO3 cytoplasm extends through pores- aids in swimming, shell formation, feeding symbiotic algae often lives under shells 90% are fossils

Algal Blooms rapid increase in the population of algae in an aquatic system blooms of dinoflagellates cause red tides- produce neurotoxins some algal blooms caused by an excess of nutrients- algae uses up all O2 and other organisms can’t survive (eutrophication, in freshwater lakes)

Sources Campbell, Neil A. Biology: Third Edition. Benjamin/Cummings Publishing Company: New York, 1993. Wikipedia.