What are Dinoflagellates? Protists A type of Algae A major component of marine food chains 90% of dinoflagellates are aquatic Microscopic, largest are about 2mm diameter They reproduce asexually Ceratium Dinoflagellates

Dinoflagellates in Symbiotic Relationships Some have a mutual relationship with cnidarians which make up coral reefs. Zooxanthellae dinoflagellates provide energy for coral in return for protection, shelter, nutrients, and CO2 needed for photosynthesis. Dinoflagellates in Parasitic Relationships Some dinoflagellates that do not have chloroplasts must feed on other animals. Zooxanthellae: Dinoflagellate algae in coral Amoebophyra sp. : Parasitic Dinoflagellate

Pfiesteria Pfiesteria is a special parasitic dinoflagellate: it has the capability to become temporarily autotrophic by taking chloroplasts from other photosynthetic protists. Pfiesteria is responsible for many fish kills.

Structure and abilities Most dinoflagellates are unicellular Each species has a characteristic shape reinforced with plates of cellulose. These plates are called thecae Many have two flagella which creates a spinning movement Some are even capable of bioluminescence for defense, offence, camouflage, and communication Dinoflagellate Structure

Life Cycle of Dinoflagellates 1.Asexually reproduce: are haploid 2.Act as gametes, pair up, and form diploid zygotes 3.Make new theca (the cellulose plate) 4.Flagella are lost, thecal plates break off and red pigments are produced (this is known as blooming) 5.Dinoflagellates then rest on the sea floor 6.Undergo dormancy and then division

Red tides

Review Questions 1.What are the cellulose plates of dinoflagellates called? o thecae 2.Name three reasons for bioluminescence. o Three of: defense, offence, camoflauge, communication 3.What is special about a Pfiesteria? o It can temporarily take chloroplasts from other photosynthetic protists making it temporarily autotrophic. 4.Why does a red tide occur? o When the dinoflagellates bloom 5.Why are red tides dangerous? o Toxins 6.Name an example of a symbiotic relationship involving dinoflagellates. o Zooxanthellae and Coral Video: For more information on Dinoflagellates, click hereclick here